Philosophy and Philosophers - an Introduction to Western Philosophy - Chapter 4
back to ...
or ...
CHAPTER FOUR
Rationalism:
Descartes, Spinoza, Leibniz
The philosophers of the seventeenth and eighteenth centuries are often
separated into rationalists and empiricists. While this distinction
certainly blurs similarities between philosophers of both “schools”,
this retrospective classification has some value at least in bringing out
tendencies of the philosophers grouped under these headings. The
contrast chiefly lies in what is said to be knowable by pure reason
alone. Some factors consistently underlie rationalist philosophy.
Rationalism holds that the human mind has the capacity, logically
speaking, to establish truths about the nature of reality (including
ourselves) by reason alone independently of experience; indeed, if
knowledge of the fundamental structure of the world in the proper
scientific sense is possible, then it must be derived from reason, which
alone has access to the required certain, necessary, universally valid,
timeless truths; the senses inform us only of what is uncertain,
contingent, particular, perspectival and transient. These necessary
truths about the world can be known to be true merely through our
properly understanding the concepts they involve or are deduced from
such truths, and ideally they form a single deductive system. Truths
known a priori by pure understanding, if they do not concern the
world as it appears in perception, instead concern a really existing
intelligible world that underlies the appearance of changing
particulars that we experience; this underlying reality makes
intelligible, and ultimately explains, the appearances. The intellect has
access to concepts, and the terms that express them, whose meaning
does not depend on being referred to some feature of our experience.
Thus there is, according to the rationalists, a reality whose nature is
comprehended by the intellect (reason or understanding) alone and
which stands behind the mere appearance of things; it is this ultimate
reality which delivers the conceptions which bring the explanation of
the way the world is to an end.
74
The rationalists do not disregard the senses, but they share the
characteristic of thinking that knowledge based on experience is
inferior to that derived from reason. The rationalist contention is that
the world has an underlying real structure of natural necessary
connections, which is logically understandable by reason and
deduction alone; this does not inevitably lead to the advocation of an a
priori methodology in science—as if all scientific truths can actually be
discovered just by sitting and thinking—for although in principle or
ideally the world is understandable a priori by the intellect alone, in
fact we as humans have a limited capacity to determine the nature of
the world independently of experience; scientific truths are often in
fact discovered by us through experience. Moreover, the necessary a
priori truths of metaphysics concern not the world of appearances,
which is the subject matter of science, but a reality beyond
appearances.
There is the conviction among the rationalists that everything is in
principle rationally explicable; one can never rest content with features
of the world for which a reason cannot be given as to why they
necessarily are a certain way and not otherwise. The tendency of
empiricism is to admit that there are a priori necessary truths knowable
with certainty independently of experience, but to deny that such
truths can determine anything about what really exists or the real
nature of the world, because in all such cases we are dealing with the
contingent features of the world we experience, and not what is
necessary concerning a supposed world beyond possible experience.
Descartes
The importance of Descartes in Western philosophy can hardly be
overestimated; he shaped the kinds of questions and answers which
were to dominate Western philosophy for many years; and, with some
notable exceptions, this approach has only seriously been questioned
in the twentieth century.
René Descartes (1596–1650) was born in France, in a small village
near Tours that is now called La Haye-Descartes. His constitution as a
child was poor. He was educated at a Jesuit college at La Flèche in
Anjou. Here he encountered scholastic doctrines that his philosophy
was to reject; but he also discovered his love for and great proficiency
at mathematics; and he remained a Catholic all his life. Descartes had
the desire to travel and experience the world of practical affairs, and to
this end he joined, unpaid, the army of the Dutch Prince Maurice of
Orange and later the army of the Duke of Bavaria.
While in Holland he encountered Isaac Beeckman, who encouraged
Descartes to consider questions in mathematics, physics and
philosophy. On 10 November 1619, he spent the night by a large stove
Descartes 75
in Ulm; there he had a vision, and later three dreams, concerning how
he might lay the foundations for a unified science which would
include all human learning. From 1625 he spent two years in Paris,
where he lived the life of a gentleman; he gambled, and was involved
in a duel over a love affair. In 1628 he began writing, in Latin, Rules
for the direction of the mind, which was unfinished and unpublished in
his life time. This states the overall projects that were to preoccupy all
of Descartes’ philosophy: that of founding science on absolute
certainty, free from sceptical doubts, and that of devising a method of
inquiry which, if properly followed, would lead science inexorably to
certain truth.
Descartes spent most of the period from 1628 to 1649 in the
relatively liberal atmosphere of Holland. The death of his five-year-old
illegitimate daughter Francine in 1640 was his life’s great grief. He was
secretive about his whereabouts, and lived in many different houses;
he also had a great desire for solitude, although he was not always
without company. In 1647 Descartes had dinner with the philosophers
Gassendi (1592–1655) and Hobbes (1588–1679), both of whom were
critics of Descartes’ Meditations.
Descartes received criticism of the Meditations from various
theologians, and most fruitfully from Antoine Arnauld (1612–94). All
these criticisms are printed as Objections and Replies; the latter of these
being Descartes’ responses. We are fortunate that as well as producing
his major writings, he engaged in extensive correspondence with many
people about his ideas. Towards the end of his life Descartes developed
a friendship with the exiled Princess Elizabeth, daughter of Elector
Frederick; he replied in letters to her acute questions. He acquired
royal patronage from Queen Christina of Sweden, and was persuaded
in 1649 to go to Stockholm. There he continued his long-standing habit
of rising late, having spent some hours in the morning reading and
writing in bed. In Sweden he led a lonely life, and in 1650, in the
winter, he contracted pneumonia and died. His last words are said to
have been “My soul, we must leave”. Although initially buried in
Sweden, his body was eventually transferred to the church of SaintGermain-des-Prés,
and his skull is to be found in the Musée de
l’Homme, in Paris.
The overall aim of Descartes’ philosophy might be said to be the
attempt to free explanations of the nature of the world from confusions
and conflicts, and set them on a path that would lead to a unified
explanation of things that was true, and, because it was also certain,
free from scepticism. Descartes made a significant contribution to the
revolution of how man viewed his place in the universe, and the
proper way of pursuing truths. His particular contribution to this
revolution in thought is the egocentricity of his approach: the
foundation of truth and knowledge begins by working from what is
most evident to the mind of the individual.
76 Rationalism
In the dedication to the Meditations Descartes seems to have other
aims: proofs of both the immortality of the soul and the existence of
God. It would be wrong to suppose that he was insincere in his
expressed concern for these matters. However, the concern of enduring
importance for modern readers lies in his aim and method in securing
a scientific, in particular mathematical, understanding of the world
that is secure against even exaggerated sceptical doubts. More
generally this involved a search for a method of ridding ourselves of
beliefs not known to be true, and maximizing those which are known
to be true. Descartes presents such a search to us in the Meditations in
the form of a personal odyssey. This is a kind of intellectual record so
that anyone might follow the same procedure at least once in his life,
and by it strip his mind of the accumulated rubbish of uncritically
accepted beliefs. Descartes sets out in the Meditations not merely the
arguments for his philosophy, but also a convincing route we can
follow which will enable us to overcome the psychological resistance
we may have to such a journey. It is the path which should be followed
by the seeker after the ultimate foundations of knowledge; in
particular it involves showing that a mathematical physics of the
world is attainable by creatures with our intellectual capacities and
faculties.
Descartes sets out on an extraordinary procedure of answering the
most extreme scepticism about knowledge and rationality by
embracing that scepticism; he then attempts to show that something
remains that cannot conceivably be doubted even after scepticism has
been applied in its most stringent form, and that what remains is
sufficient to secure the foundations for knowledge. The tool used to
this end is the “method of doubt”.
The final position at which Descartes wishes to arrive is that we can
have objective knowledge of the world; knowledge independent of the
way we happen to be biologically constituted; disinterested knowledge
that aims to divest itself of our perspective, and that tells us how
things really are in the world. Descartes thinks that such an objective
conception must be independent of our contingent sensory faculties,
since we have no guarantee that our senses present to us the world in
its fundamental form; after all, if our senses changed, the world would
appear differently. So the aim is to produce a way of describing the
world based on conceptions which would not change if our senses
changed; a world whose laws we could fraternally share with any
rational beings. To be objective our science must be sense-independent,
and derived from reason or the faculty of understanding. Descartes
sets out to show that when the mind is emptied of all sense-dependent
beliefs, it is not empty of ideas or concepts, and that the ideas that
remain are sufficient to form the basis for science. This involves a belief
that we have innate ideas independent of the senses; we have such
ideas concerning mathematics and geometry. By “ideas” here
Descartes 77
Descartes does not mean images; he means concepts. Descartes
attempts to show that the fundamental explanations of all phenomena
can be derived from a mathematical and geometric conception of
reality independent of sense-experience. Descartes aims to
demonstrate that mathematical geometry can be applied to the
explanation of the world of material things because, contrary to the
appearance of a vast array of natural kinds of things in the world, the
only essential properties of matter are geometric; that is, matter
stripped of all properties other than the ones which geometry deals
with will still be matter, and will be matter if and only if it has those
properties; those properties are extension, shape and motion, of which
extension is primary. The essential properties are those properties
which a thing cannot lack and still be the kind of thing it is.
Descartes in many ways can be seen as opposing the Aristotelian
science; Aristotle takes at face value the division of the world into
what appear to be natural kinds of things. An Aristotelian scientific
explanation of some phenomenon associated with a thing is then
obtained by deducing the phenomenon from an intellectual
examination of the essential nature of that thing given by a real
definition, or from a more general category of which the thing is a
part. The identification of genuine natural kinds, from which
explanations are to be deduced, is very difficult. However, Descartes
does not reject essentialism, which is the view that we eventually reach
a certain category of stuff beyond which we cannot go since we have
reached that which is most ontologically self-sufficient, and from
which we derive explanations of everything else that appears to us in
the world. But instead of a vast array of the natural kinds there appear
to be, Descartes, in the case of the material world, reduces this to one
fundamental kind: matter as extension. It is in terms of this underlying
reality behind appearances that the variety of features making up
appearances are to be explained. The explanation of a vast array of
different phenomena is thus simplified and unified under a more
general conception which reflects the fundamental nature of reality.
The tendency of Descartes’ philosophy, and the revolution of which his
philosophy is a part, is to reopen the gap between how things appear
to us in perception, and how they really are in themselves; moreover,
how things really are, which should form the basis of the explanation
of appearances, has to be comprehended by intellectual contemplation
or thinking, not experience. This marks the distinction between
primary qualities, which are the real qualities things have
independently of perceivers, and secondary qualities, which are in
objects as arrangements of primary qualities (say particles in motion),
but which produce in perceivers quite different ideas, like the
experience of heat and red.
First, Descartes has to deal with radical scepticism. The method of
doubt seeks to eliminate all beliefs not known to be true which may
78 Rationalism
taint and infect the truth; it does this by rejecting as false all beliefs it is
possible to doubt; that is, it rejects all beliefs whose falsity is possible. In
this way Descartes meets the sceptic head-on. This is done not because
he thinks all those beliefs it is possible to doubt the truth of are false;
rather, it is a way of making certain in one go that no false beliefs slip
through and are mistakenly accepted as true. It is important to note
that Descartes is not suggesting that we adopt such scepticism in our
everyday life; Descartes’ doubt is a method adopted for the pure
project or special purpose of securing the first principles or
foundations of all knowledge, disregarding all practical concerns.
Straight away we can note that we do, after all, find cases of things we
once believed to be true turning out to be false. Even without sceptical
doubt, Descartes’ view that we should make a fresh start makes sense;
we have over our lifetime accumulated uncritically a mass of beliefs
from which we make all sorts of inferences; but any falsity among
these beliefs is likely to infect any inferences we make and conclusions
we draw from those beliefs. If we then arrive at true conclusions, even
in valid inferences, it can only be by a sort of luck.
What remains after this process of sceptical doubt is not a massively
rich axiom from which all that we would wish to claim we can know
can be deduced, but something which, when examined for the reason
for its immunity from doubt, will give us a criterion to distinguish truth
from falsity. That criterion is clarity and distinctness. Descartes does
not wish the criterion to be merely a notion of subjective obviousness,
but he is unable to formulate it in terms of primary truths or logical
truths whose denial implies a contradiction, in the way that Leibniz
does; rather, Descartes explains it as our possessing intellectual
intuition giving us an ability simply to see that certain propositions or
beliefs, once fully understood, must be true. After this we can begin to
reinstate many of those beliefs we previously supposed false. In this
search we take time off from practical concerns and constraints, and
apply the criterion single-mindedly.
Descartes embarks on his method of doubt by disposing of the
range of beliefs in three classes: first, we abandon sense-based beliefs
by accepting that the senses may deceive us; second, we abandon the
belief that we can have knowledge of real “simple natures”; third, we
abandon the belief that God exists. A belief in the existence of God is
simply dropped, both because Descartes has no wish to assume one of
the things he sets out to prove, and because if the existence of a
beneficent God were granted the radical scepticism Descartes
envisions would not be plausible. Descartes also wishes to show that
there are degrees of doubt involved in these classes of beliefs, and to
indicate the order of trustworthiness in which we should reinstate
them; he also wishes to make the method of doubt psychologically
convincing. To these ends he suggests two hypotheses: the “dream
hypothesis” and the “evil demon hypothesis”.
Descartes 79
The first of these—the dream hypothesis—points to those occasions
on which I thought I was awake when in fact I was dreaming. Our
sleeping dreams may also be phenomenally or qualitatively
indistinguishable from our waking states: I may be convinced I am
awake and seeing real things when I am in fact asleep. This suffices to
undermine the trust we may have in the senses as representing to us
something real. This doubt extends to the existence of my own body,
which brings us to the second class of beliefs: the existence of “simple
natures”. When we dream we dream about something, and that
something must conform to the most simple and universal categories
such as extension, shape, duration, number, movement. Even if what
we dream of does not exist exactly as we dream about it, it is still
possible, and less doubtful, that simple and universal natures exist; for
example, objects with extension. Thus an object of a specific shape
might not exist because we might dream about an imaginary unreal
object of that shape; but that is not the same as showing there are no
objects with shape: shape as such does not exist. Even dreaming
involves objects considered under the simplest categories and concepts
which are surely real. Horses, and bodies of particular shapes, may not
exist, but it is less doubtful that there exists a world of extended
material things at all. Moreover, the greater security of mathematics
and geometry derives from its dealing with simple natures (such as
number and shape) and their necessary relations regardless of whether
those general things exist or not. Geometrical proofs done in a dream
would still be valid since their validity is independent of whether
geometric objects exist. The evil demon, however, who has the active
power to deceive us has the ability to lead us to believe falsely that
there exist in the world even the most general sorts of things
characterized by simple natures. The evil demon finally makes it
conceivable that no external world exists corresponding to our idea of
a world of extended substance; the evil demon could cause our idea of
an extended world although that world does not exist. It is not always
clear if simple mathematical and geometric truths can be doubted
under the influence of the evil demon. It must be remembered that it is
not within the power even of the demon to alter logical truths and to
make 2+2=4 false and 2+2=5 true; however, the demon can make us
believe that 2+2=5. Descartes thinks it is within God’s power to alter
such logical truths. Even if we accept that beliefs in basic mathematical
and geometric truths survive the demon, we have not established that
anything exists corresponding to the simple natures; doubt as to their
existence is conceivable, so their existence is therefore not free from
scepticism. We have at best a pure mathematics and geometry which
has not been shown to apply to anything existing, for the simple
natures are what it would deal with.
What remains that cannot be doubted is cogito ergo sum: I think,
therefore I am. For however the demon may twist and turn in his
80 Rationalism
attempt to trap and deceive us, and lead us to accept doubtful and
false beliefs, there is one belief I cannot doubt: that whenever I think, I
exist. This belief is somehow self-verifying; the mark of truth is
intrinsic to it and does not depend on accepting any other truth. Even
if the content of that thinking is itself an act of doubting, this too could
not take place unless I existed. The cogito is the necessary condition for
all reasoning—even all deception. Each time I entertain the cogito it is
certainly true.
What is more, I am essentially a thing that thinks, for, although I can
doubt that I have a body and still exist, I cannot cease to think and still
exist. Descartes believes that he is essentially a thinking thing: he is
necessarily immaterial (incorporeal) if he exists at all, and only
contingently embodied. The question of whether he is entitled to this
conclusion is much disputed; but one obvious objection has been that
it does not follow from the premise “I necessarily exist whenever I
think” that “I am necessarily only a thing that thinks”. We might
accept that “I think” entails “I exist” without agreeing that “I exist”
entails “I think”; I may still exist in some other way when I do not
think. Therefore I may not be essentially only a thinking thing. There is
indeed some doubt as to how much weight Descartes puts on this
argument. Whatever we think of this, Descartes is committed to the
view that he is essentially a thinking thing, and that thought is his only
essential property. Descartes of course presents more than one
argument for this view.
By essence Descartes means some property, or set of properties, f,
such that if f is an essential property of X, then X cannot be an X
without possessing property f; if f is the essence of X, then X cannot be
what it is or the sort of thing it is without f. Thus, f is a necessary and
sufficient condition for X to be what it is independently of the fact that
it is. In a case where there is only one essential property, as with mind
and matter, that property is alone both necessary and sufficient.
Descartes thinks we can know—that is, have clear and distinct
conceptions of—what mind and matter are before we know whether
any exists or not. For Descartes, as for other rationalists, only God has
existence as part of His necessary and sufficient conditions for what
He is: God. In this way Descartes draws the distinction, criticized by
Spinoza, between true substance, God, and the finite or created
substances mind and matter.
As it stands, the cogito is merely a subjectively certain truth; it is
time-bound; its certainty is restricted to those times when it is
actually being entertained. Descartes obviously wishes to move
beyond the perpetual reiteration of this one truth. What makes the
cogito a certain truth is that it is clearly and distinctly perceived.
Descartes makes use of an analogy with sense-perceptions: an idea is
clear in so far as we attend to features of which we are forcefully and
immediately aware, and an idea is distinct when we attend only to
Descartes 81
those features which are clear, and thus do not make inferences
beyond that of which we are immediately aware. This turns out to be
awareness of the essential nature of the objects of one’s awareness;
and awareness of an object’s essence means that the object of
awareness could not be confused with anything else. The thinking
behind clear and distinct ideas is that there must be a “natural light”
of reason that allows a direct grasp or intuition of some truths with
certainty, independently of the acceptance of any other truths. They
are grasped by anyone who can reason and can understand at all. If
some truths are not immediately manifestly true on intrinsic grounds
alone, following our full understanding of them, without any further
(“external”) justification, then all reasoning would be impossible,
since it could never get started. Those propositions which we can
clearly and distinctly conceive, or intuit, can be known to be true
because we can see they must be true merely from completely
understanding them. Such truths can be seen as analytic: they can be
known to be true merely from understanding the meaning of the
terms they involve.
One problem with the cogito is that in it Descartes does seem to go
beyond what he is immediately aware of; what he is aware of is
particular acts of thinking; but this falls short of establishing a durable
“I” or self as a mental substance on which the thinking depends.
Descartes’ plan is then to move from the two features of the cogito,
thinking and existence, to prove the existence of God. Having
established the existence of God, Descartes relies on our
understanding of the nature of God as an all powerful, perfect and
benevolent being to say that, as deception is an imperfection, God
would not deceive us in that which we most clearly and distinctly
conceive: that is, truths that are knowable through the understanding
alone. If I do not go beyond judging as true that which I clearly and
distinctly perceive, then I will always judge truly, and I will not
entertain falsehoods.
What I clearly and distinctly understand about things is the
essential properties of those things; those properties without which
those things cannot be the kind of things they are; those properties
which, if I think about those things at all, cannot be separated from,
and so must be part of, my conception of those things. These are the
defining properties of substances, on which all the other apparent
qualities of things rely. There are three substances according to
Descartes: matter, whose essential property is extension; mind, whose
essential property is thought; and God, whose essential properties are
perfection, omnipotence, benevolence, infiniteness, and existence.
Only God contains existence as part of His essence; that is, among the
necessary and sufficient conditions for being God is existence. But the
created substances of matter and mind are distinguished by relying on
nothing else apart from God for their existence. The same cannot be
82 Rationalism
said for colour, for example, which relies on there being an extended
physical object which is coloured.
If we examine the essential properties of mind and matter, we
discover that it is the intellect, independently of the senses, which
gives us our understanding of them. If we conceive of mind and
matter, and we imagine away all those properties which seem
unnecessary to their being either mind or matter, we find that we are
left with the essential properties; thought in the case of mind, and
extension in the case of matter. Without these properties neither could
have any other properties at all; the essential properties are what all
other properties depend on. All the other properties can change, but
without extension and thought, matter and minds respectively would
not be what they are. These essential natures remain constant to give
identity to matter and minds through the changes they appear to
undergo according to our senses, and even when all the sensory
qualities have changed; the intellect reveals the underlying reality
upon which sensory appearances are a kind of clothing. If the senses
are eliminated by sceptical doubt, it is by the sense-independent
conception of the understanding that the essential properties or
intelligible properties remain known to us. The essential properties
these substances have are what remains constant through change, and
makes sense of the continued identity of a thing over time through
accidental change. If essential properties change, we do not say that X
has acquired property g and lost property f, we say, rather, that X has
ceased to be X; it ceases to be the same substance if it loses its essence.
What makes a material thing (for example, a piece of wax) a piece of
matter through its various appearances is not sensible qualities
(something we perceive by sense), for these can all alter; the
conception of a material thing revealing its essence, by which we
identify it as the same material thing through its various appearances,
is therefore given through inspection by the intellect.
The thinker who has reached the intuitive certainty of his own
existence and the essential nature of that existence has still to get
beyond this. Descartes distinguishes between levels of reality, or being,
by degree of ontological dependence; the more independently a thing
exists, the more formal (actual) reality it has. Descartes distinguishes
between objective and formal reality. An idea has a certain degree of
formal reality as an entity in itself; but it also has an objective reality—
its content, what the idea is about—which may differ from its formal
reality as an idea. The cause of an idea must have at least as much
formal reality as the idea has objective reality; that is, the actual cause of
an idea must have as much reality as the content of the idea. One idea
we have is the idea of God. In the case of the idea of God we have an
idea with infinite objective reality since the object of that idea has
infinite formal reality. An idea with such a content (such an object)
could not be caused by something merely finite, with less formal
Descartes 83
reality than the content, like ourselves, but must have as its cause
something of equal or greater actual or formal reality; so only God can
be the cause of our idea of God. This is a cosmological argument for
God’s existence. The notion of levels of reality can be summarized in
the following diagram; the arrows show the direction of decreasing
formal (actual) reality.
The other argument Descartes uses to prove God’s existence is the
ontological argument. God contains, by definition, all perfections, and
one of these perfections is existence itself. Therefore God exists. One
problem here is involved in suggesting that existence is a predicate
rather than a term confirming that predicates are actualized. Another
problem is that, although it may be part of God’s definition that if He
exists, then He exists necessarily, it may still be questioned whether
anything actually satisfies that definition.
A serious problem for Descartes’ arguments which aim to escape
the exaggerated doubt is the charge of circularity: the Cartesian
Circle. If we are dependent on the existence of God to free us from
scepticism, it is important to see how far this dependence extends. If
the dependence extends to God being our only guarantee of the truth
of even that which we most clearly and distinctly perceive, then it is
impossible to see how there can be any rational proof of God’s
existence; in that case the truth of any of the premises and the
reliability of any of the inferential steps in the proof would logically
depend on the outcome of the proof: God’s existence. We cannot,
without circularity, prove God’s existence by means of propositions
and arguments whose truth and validity depend on assuming God’s
existence. It is not clear what Descartes’ final view is on this. One
suggestion has been that God’s role is not to guarantee clear and
distinct ideas themselves as we intuit them—since they are in that
case as certain as they could ever be—but to obviate the necessity of
our running constantly through proofs to reassure ourselves. The
central problem then with the proofs of the existence of God is not
their circularity but their questionable validity and the dubiousness
of their premises.
Descartes, however, thinks he has proved the existence of God.
Having done this he can begin to reinstate some of the things cast
84 Rationalism
aside by the method of doubt by invoking the nature of God. In the
case of the material world, what we clearly and distinctly perceive
about it is that it is extended; and this is something grasped by the
intellect, not the senses; it follows from our merely properly
understanding the concept of matter. God would not deceive us about
what we most clearly and distinctly perceive. Those ideas that we
most clearly and distinctly conceive are innate; and once God’s
existence is proved, the truth of those ideas we identify as innate by
subtracting the sense-derived ideas is also guaranteed by their being
directly planted in us by God. This then gives us a pure physics of the
world, but it is one that is hypothetical: we have a clear and distinct
idea of what matter is as being essentially extended, but the question
remains as to whether such matter actually exists. God is required
again in order to demonstrate the possibility of an applied physics.
The ideas I receive when I perceive a material world, which I suppose
are caused by external bodies, could indeed have as their cause
external bodies, but their cause might also be myself, or derive
directly from God. These ideas come to me unbidden so I cannot be
their cause, and I have a strong belief that they derive from material
bodies; if the source of the ideas was other than what I strongly
believe it to be, God would be allowing me to be deceived; but God is
no deceiver; therefore bodies exist. This argument aims to prove the
existence of the material world. This establishes the possibility of
applied physics within what I clearly and distinctly perceive about
bodies. If we judge as true only that which we clearly and distinctly
perceive, God guarantees that those judgements correspond to actual
states of affairs in the world.
All that has been established in Descartes’ argument has been
established by pure reason alone independently of information
derived from the senses; the senses have been denied any role by the
sceptical doubt. Truths must be tested by reason, not by the unreliable
senses.
If God is no deceiver, why does he let us make mistakes at all?
Letting us make mistakes is not the same as actively deceiving us.
Descartes is clear that such mistakes as we make are our responsibility,
not God’s. The mind is made up of two chief faculties: intellect and
will. We make mistakes when we allow the will to push beyond what
is clearly and distinctly perceived by the intellect. God gives us the
possibility of avoiding error: we merely have to stick within what we
clearly and distinctly perceive: propositions we can know to be true
purely by fully understanding them.
If this is the case, it tends to undermine Descartes’ proof of the
existence of the material world. His argument depends on the notion
that God cannot be a deceiver and would be deceiving us if he allowed
us to believe strongly that material objects were the cause of our
perceptions of material objects when they are not the cause. But God
Descartes 85
could only be accused of deception if in those circumstances He either
implanted the belief in us, or such a belief was a clear and distinct one.
Descartes does not attempt to demonstrate the former, and the latter is
obviously not the case. So it is perfectly possible that God is not a
deceiver and that material objects do not exist as the cause of our
perceptions of material objects. Descartes has already admitted that
God lets us make our own mistakes in judgement and these are likely
to occur when we make judgements beyond what we clearly and
distinctly perceive to be the case.
Descartes gives a dualistic conception of reality; there are two basic
substances in the world, mind and matter. These two give at least the
appearance of interaction: things in the world act on my sensory
organs and result in perceptions; I will my arm to move, and it moves.
But the problem arises for Descartes of how a non-spatial (unextended)
substance, which cannot thereby be in motion, can cause the motion of
extended substance, or how motions in our bodies can cause changes
in consciousness. Mind and matter have no properties in common, and
it is difficult to see how their interaction can be rendered intelligible.
They are created substances dependent on God for their existence, but
apart from that the explanation of their states should be independent
of any causes “external” to their own type of substance. Descartes’
motivation for dualism derives from his belief in both the immortality
of the soul and the possibility of free will. The immortality of the soul
is maintained by the soul being an independent substance which
might survive the dissolution of the body. Free will is maintained by
making the soul independent of the deterministic mechanical laws
which govern matter; then our behaviour is not governed by
mechanical compulsion, but can be acts done out of choice in
knowledge of good and evil.
It is important to summarize some of Descartes’ achievements. They
are mainly seen in his attempt to gain a more objective point of view of
the world, and this requires a conception of the world which is nonsense-based;
an objective conception is non-species specific, and
independent of the way we happen, contingently, to be biologically
constituted. Some of our view of how the world is is contributed by
our natures; and to get a view of how the world really is (how it is in
itself), it is necessary to strip away as much as possible of the elements
in our conception contributed by the particularities of our perceptual
apparatus and perspective. Certainly the sense organs we happen to
have could alter to give us a different view of the world, but the world
would not thereby be different. The objective conception of the world
is a conception which is universally valid, revealing the world as it is
in itself, a conception devoid of features that depend, as apparent
features of the world, on the contingent peculiarities of our point of
view, such as those derived from our particular sensory apparatus.
Reason provides a conception, as a source of disinterested universally
86 Rationalism
valid concepts and truths, independent of our, or indeed any, point of
view. Take an extreme example: the truth 2+2=4 would presumably be
a truth for Martians no matter what sensory apparatus they had—they
might see X-rays but not light-rays. The idea is that our view of the
world could be objective and universally valid in the same way. We
cannot perhaps attain this ultimately objective point of view—a God’seye,
or no-eye view—but it is something at which we can aim; only
God sees things as they are in themselves independent of any point of
view; for God there is no appearance/reality distinction, for His view
is non-perspectival.
We can obtain objective knowledge of the physical world, according
to Descartes, by concentrating exclusively on conceiving it to have
only mathematical and geometric properties. Descartes needs to start
from the point of disinterested pure consciousness, which is outside
nature; using only the resources of reason or intellect that are found
within the incorporeal consciousness, Descartes hopes to build a
unified and universal conception of nature which would be common
to all beings capable of reasoning at all.
Spinoza
Benedict (Baruch) de Spinoza (1632–77) was the son of a Jewish
merchant who fled to the Netherlands from persecution in Portugal.
The Jews who entered Amsterdam met a close-knit and strict Jewish
community to which they had to accommodate themselves by
manifesting doctrinal purity. Spinoza was taught at a school run by a
rabbi, and he became familiar with Hebrew sacred books and Jewish
theology. But in 1656 he was excommunicated from the Amsterdam
synagogue for being unable to assent to important aspects of Judaic
orthodoxy; the root of this lay in Spinoza’s increasingly critical attitude
towards the Bible. His life as an outcast from the Jewish community
necessitated that he become financially independent; so Spinoza came
to make his living as a lens grinder. Although towards the end of his
life he was offered a professorship at the University of Heidelberg, he
declined it as a threat to his intellectual freedom—he thus never held
an academic post.
The advocacy of toleration, particularly the opposition to religious
fanaticism, was a mark of Spinoza’s outlook, surrounded as he was
by violent schisms of every sort. Spinoza was held in great affection
by his friends—friendship between those who in common seek truth
being something, in the Aristotelian tradition, he valued highly.
Something of Spinoza’s inner strength and personal bravery is
indicated by two incidents toward the end of his life. In 1670, while
living in The Hague, Spinoza received a small annuity from Jan de
Witt, Grand Pensionary of the Netherlands and an enlightened
Spinoza 87
advocate of religious freedom. De Witt was accused of treachery in
1671 when England joined forces with France against the
Netherlands; an angry mob seized de Witt and his brother and beat
them to death. In an uncharacteristic display of recklessness, Spinoza
was prepared to confront the mob and denounce their barbarism, but
he was dissuaded from this course of action. Later, in 1677, following
his appointment to a peace mission to France, Spinoza too came
under suspicion as a spy; his house in The Hague was besieged by an
enraged mob; again Spinoza was prepared to try and face down the
crowd despite the possibility that he might be killed in the same
manner as de Witt.
However, these are incidents untypical of Spinoza’s life, most of
which was spent in independence and simplicity; he was stoical in
outlook, and dedicated to intellectual and scholarly pursuits.
Fortunately he was able to discuss his philosophical views with
tolerant Protestant friends. He was uncomplaining, and cautious;
suspicious of violent emotions (which is not to say he was unfamiliar
with them), knowing well their destructive power; but he did not
thereby lack either charm or warmth. He smoked a pipe, and liked to
drink beer. He was unmarried, thinking that such emotional
attachment would disrupt his scholarly study; although it seems that
he had been disappointed in love early in life. The consumption from
which he had suffered for many years, aggravated perhaps by the glass
dust he breathed in his work as a lens grinder, claimed his life in 1677.
Spinoza’s interests wandered freely across mathematics and the
various sciences. Among Spinoza’s modest library there was the Bible,
books of Euclidean geometry, works on optics, and astronomy. This
apparently likable man was vilified both during and after his life,
variously as heretic and atheist.
Spinoza’s correspondence aids our understanding of his
philosophy: that with Henry Oldenburg, who became secretary of the
new Royal Society in London, but most important that with the
scientist Tschirnhaus. In 1676 Spinoza was visited by Leibniz; he
overcame Spinoza’s initial wariness to the extent that Spinoza
allowed him access to the unpublished Ethics. Spinoza also became
acquainted with Christiaan Huygens who originated the modern
theories of optics, and corresponded with Robert Boyle, the founder
of chemistry.
There are probably three main influences on Spinoza’s philosophical
views: scholastic Aristotelianism transmitted through the early Jewish
thinker Maimonides (1135–1204); Cartesian philosophy; and the works
of Hobbes. Spinoza came to reject, or modify massively, all of these
influences.
To gain full understanding of Spinoza, it is the Ethics on which one
must concentrate. The Ethics is a work of stupendous ambition.
Spinoza aims to connect how the world necessarily really is at its
88 Rationalism
deepest level with the practical concern of how we should live our
lives and attain a blessed peace (acquiescentia) of mind. This project has
a good deal to do with ways of controlling, but not eliminating, the
emotions; emotional states and reactions are inextricably linked to
beliefs; if we see that certain of the beliefs we hold are false, we can
thereby change the emotions connected with those beliefs. This
suggests that through a form of cognitive therapy there can be some
control over emotions.
The Ethics is set out in a form which follows the methods of
geometric proof: using axioms, definitions, and postulates, from which
propositions are inferred by deductive reasoning. It uses a highly
abstract and technical language, much of which derives from the
medieval scholastic tradition—although its views are quite opposed to
scholastic metaphysics. Spinoza aims to start from first principles
which he thinks self-evidently true, and then logically deduce what
consequences follow; thus the propositions that follow are proved and
necessarily true. The definitions are not merely stipulative (arbitrarily
laying down how a word will be used); they are meant to be true of the
objects to which they refer; they are “real definitions” which can be
true or false because they aim to give the necessary and sufficient
conditions for their reference being what it is; that is, such definitions
give a thing’s essential features. Nevertheless, the definitions often
depart greatly from common usage. The axioms are both self-evident
and primitive: they are obviously true, and not derivable from
anything simpler.
The heart of Spinoza’s philosophy is the nature of substance. Certain
aspects of the world seem to be dependent on other aspects for their
nature and existence; if anything in the world is ultimately real in
being fully independent—and we are not to embark on an infinite
regress—we must reach something that does not depend for its nature
and existence on anything else. The rationalist contention is that by
chasing down the ladder of dependence, our intellect or reason will
reveal what satisfies the conditions for ultimately independent being
which is fully self-explanatory and explains everything else, so
nothing whatsoever is left unexplained. The universe as a whole must
have no superfluous features in its nature or existence that are
inexplicable in being not deducible from its total concept. Spinoza is
dissatisfied with Descartes’ analysis of substance; Descartes’ notion of
the “created substances” mind and matter is for Spinoza a mistake
because they are not fully self-explanatory. There are, for Spinoza, two
main conditions which must be satisfied for something to be regarded
as a substance:
(a) Whether that thing is self-subsistent or self-caused (causa sui):
that which has the most independent sort of nature and existence
and does not owe its nature and existence to anything else.
Spinoza 89
(b) Whether that thing can be totally conceived—understood or
explained—through itself alone, without involving any
conception of another thing outside it.
And there is a third point to be borne in mind which ultimately derives
from Aristotle:
(c) A substance is that which is a subject (ultimately: always a subject)
and not a predicate (ultimately: never a predicate). It is the subject
of predication, and not predicated of anything; it is what remains
the same through changes in predication.
So substance is that which is self-caused, self-explanatory, and the
ultimate subject of all predication. This amounts to saying that true
substance must be such that all of its features are deducible from its
essence.
Spinoza is committed to some form of the ontological argument:
God, and only God, exists necessarily, since God’s essence involves
existence; it would therefore be a contradiction to suppose God did not
exist. So God exists and, moreover, only God can fulfil the conditions
for substance, therefore there can be only one substance. It is a mistake
to regard mind and matter as substances: they are not fully selfsubsistent,
but are dependent modes or manifestations of God. Only
God includes existence among the necessary and sufficient conditions
defining His nature. A true substance must be that which contains
within itself, as part of its essence, the complete explanation of its
nature and existence.
This complete causal autonomy and explanatory autonomy amount
to the same thing. If we have a clear and distinct conception of things,
which we derive from self-evident truths intuited by the intellect, then
the consequent logical deductive links between the concepts will
correspond to causal links between things. In this way, the underlying
structure of the world is seen to be one reflected in necessary
deductive links. This conflates (in a way unsatisfactory to empiricists
such as Hume) causal connections with logical necessity so that: if A
causes B, then B is logically deducible from A.
It is vital to understand that Spinoza thinks that the intellect can
ideally attain a system of concepts which represents the underlying
nature of the world as a whole; and that a complete explanation of the
world would be constituted by laying out all the deductive logical
interrelations between these concepts.
Spinoza’s concept of God is not one of a transcendent God who
stands outside the world; Spinoza writes of “God or Nature” (Deus sive
Natura); God is to be identified with the totality of the universe.
Spinoza’s view of God is sometimes regarded as pantheistic. The
totality of the universe includes more than that which is material. God
is infinite and unlimited; unless one contradicts this, there can be
90 Rationalism
nothing which is not “in” God; that is, there is nothing which is not
dependent on God both ontologically and for its explanation. There
can only be a single substance; there cannot be a plurality of
substances. Substance in Spinoza has upon it the extremely restricting
definition that it must be completely self-caused (causa sui) and must
be entirely self-explanatory; and this eliminates the traditional
distinction with respect to true substance between having necessary and
contingent properties; that is, necessary properties given by an essence
or definition, and accidental or contingent properties, derived from the
conception of another thing that is an external cause; to be a true
substance all its states must follow necessarily or deductively from its
essence or definition, otherwise it would not be completely
independent in being its own complete explanation. Spinoza identifies
true substance with God or the totality of nature because only that can
satisfy the conditions of a true substance by being fully the cause and
explanation of itself; it satisfies these conditions simply because, by
being the totality of what there is, there is nothing else that is required
to be, or could be, its cause or involved in its explanation.
To suggest that there could be two or more substances would be to
suppose the following.
(i) To suppose something—assuming that everything has to be
rationally explicable—outside the plurality of putative substances
which explains the plurality; but then this contradicts the
definition that true substance must be entirely self-explanatory.
(ii) To suppose that a substance could be limited; but limitation
entails that part of the explanation, and thus of the cause, for the
substance being as it is does not lie within it, but depends on
another thing outside it explaining its limitation; but then
something limited like that could not be a true substance because
true substance is by definition fully self-explanatory.
There are two alternatives here in talking of a plurality of substances:
there could be two or more substances with different attributes or
essences, or two or more substances with the same attribute or
essence.
(a) The possibility of there being two substances with different
attributes is ruled out by the definition of God as having all
attributes; God, as it were, uses up all possible attributes, so if
there is a substance other than God, it must have the same
attributes as God.
(b) So if there is more than one substance, then those substances
must have the same attributes.
Spinoza therefore aims to show that there cannot be two or more
substances with the same attributes—the same essence. If they differ in
attributes, then we have two substances with different attributes,
Spinoza 91
which is not what we are looking for. If two things differ only in mode,
and modes are modes of substance and not themselves substances,
then a difference merely in modes does not mark a difference in
substance; since we are by hypothesis dealing with a difference only in
mode, and not in attribute, the modes must be modes of the same
substance; two things that differ only in mode are therefore essentially
the same, and are not therefore different substances.
Moreover, we would have no reason to regard “two things” with the
same attributes—differing merely numerically—as two; for there is no
sense in which they could be distinguished, since all their features are
dependent upon their attributes, or essence, which are here posited to
be the same; a difference in modes would involve a difference in
attributes in the case of true substance, since all its features must
depend only on itself; this means there cannot be two true substances
differing only in mode and not in attribute as well.
There cannot be a difference in substance apart from a difference in
attributes, so there cannot be two substances with the same attributes.
But there cannot be two substances with different attributes either,
because of the definition of God as a being of infinite attributes. So
there cannot be more than one substance.
Hence, true substance is utterly causa sui, cause of itself, and for this
to hold true, there can be only one substance. This unique unlimited
substance must have infinite attributes—that is, all possible
attributes—each of which is infinite in its kind. True substance is God
or Nature, and is theoretically conceivable in an infinity of ways, of
which our intellect truly grasps just two: we conceive the world under
the attribute of thought or under the attribute of extension; these are
what the intellect perceives of substance as constituting its essence.
Thus Descartes’ two “created substances”, mind and matter, are
properly seen as attributes of the one substance, not themselves two
substances.
The notion of something being the cause of itself (causa sui) may
seem incomprehensible. For A to cause itself to exist would seem to
involve A existing before A exists. But the notion of causation involved
here is that of logical deduction; the existence and nature of A is
caused by A in the same sense as the theorems of a geometry follow
from the axioms; and here the sense of following from is entirely nontemporal;
it does involves not succession in time, but rather a nontemporal
logical relation.
The notion of two attributes is partly understood as two
perspectives on the same thing—analogous to two sides of the same
coin—but here the “perspectives” are intellectual, not spatial, points of
view. There are two systems of concepts which represent or express the
order of the same thing in two ways, such that each way of talking is
irreducible to the other; explanations in both systems or schemes take
place by logical deduction using the concepts within that system only;
92 Rationalism
the two systems of concepts, within each of which there are logical
links, are irreducible one to the other; they are incommensurable. They
are two completely autonomous ways of looking at the same thing.
All that we observe in the world as particular things are either
modes of the attribute of extension (physical things) or modes of the
attribute of thought (ideas, which make up minds); all things are thus
a determinate expression of the essence of God. Infinite modes are
those features that are common to all modes that fall under a certain
attribute: motion and rest in the case of physical particles, and ideas in
the case of thoughts. Finite modes are the more particular features of
the world. Thus an infinite mode under the attribute of extension
would be described by a law of nature that applied to all physical
things, whereas a finite mode such as the red of this book is a
particular feature of the book and is not a feature common to all
physical things. The explanation of the existence and nature of
particular modes derives either from the essence of that mode,
something that lies within it “in so far as it is in itself”, or something
external to that mode, something that lies outside it. God or nature as a
totality is the only thing which has within it the complete explanation
of its existence and nature; all other things are modes which are
determinate cases of God expressed under the attribute of either
thought or extension, and to varying degrees their explanation lies
outside such modes; but in any case the full explanation must
ultimately be traced back to the nature or essence of God.
This begins to move us from metaphysics to epistemology. Spinoza
thinks that the logical order of ideas (their logical relations) is the same
as the connection of things (their causal relations). The perfect, or fully
“adequate”, understanding of the world would be attained if we could
see how everything was deducible from the essence of God. We would
then see how everything in the world follows by logical necessity from
God’s eternally fixed nature. This is more than determinism: it is
necessitarianism. One might have a variety of sets of axioms from
which different theorems could be deduced, which would constitute
their explanation or proof. But these proofs are conditional or
hypothetical in that they depend on the acceptance of the axioms: if
one accepts the axioms, then the theorems follow by logical necessity,
so that to accept the axioms (premises) and deny the theorems
(conclusions) would imply a logical contradiction. In the completely
adequate science of the world (falling under the attributes of extension
and thought) there is only one possible axiom set: the essence of God.
So the world is not explained in conditional truths deduced from a set
of basic truths which we might reject in favour of some alternative set;
the world follows unconditionally from God’s nature, which it would
be absurd to suppose could be different from what it is. God is perfect,
so any change in God would produce imperfection in God; God cannot
be other than what He is. On similar grounds Spinoza opposes final
Spinoza 93
cause or purposive or teleological explanations. God’s nature stands
immutably and eternally the same; it stands outside time. So this
world not only follows in every detail, when properly understood,
with logical necessity from God’s nature, this world is also the only
logically possible world. Not only is each link in the series deductively
connected with other links, the series itself is the only logically
possible series—the series itself as a whole is logically necessary.
Presumably this means any other series, and hence world, would
produce within it a logical contradiction.
The notion of a completely perfect conception of the world derives
from Spinoza’s doctrine of “adequate ideas”. The world, and features
of it, are always viewable under its two expressions of thought and
extension; these two worlds run in irreducible parallel; they are
isomorphic. From this metaphysics it follows that for every idea there
is a corresponding physical correlate, an ideatum. This does not mean
there cannot be false ideas, since truth involves more than mere
correspondence of an idea to some ideatum; the idea must also be an
adequate idea; this involves more than the external correspondence to
the object the idea purports to be an idea of; it must also represent the
true nature of the object represented. It is clear that Spinoza is using
the term “true” in a way different from common usage. For an idea to
be true in Spinoza’s sense it must not only correspond to the facts, but
must also be known to be true and one must know the nature of the
object to which the idea corresponds; only then is an idea said to be
adequate and true. Thus falsity is a privation of knowledge; although
an idea that failed to correspond to the facts would also be false. To
have an adequate idea of X involves understanding X, that is, knowing
the causes of X being as it is; this involves explaining X by deducing it
from other adequate ideas. Ultimately the chain of adequate ideas is
traced back to axiomatic necessary truths and concepts called
“common notions”. An inadequate idea is like a conclusion without
premises. An idea is more or less adequate in so far as it fits into a
more or less general system of explanation; the system will be more
general and powerful to the extent that features of the world can be
unified and deduced from it by deductive reasoning. An idea becomes
more adequate—thus adequacy is a matter of degree—by fitting as a
deducible conception within an ever wider, and more inclusive,
unifying, explanatory system. Complete adequacy would involve
fitting in the idea or conception deductively with the system
describing the order of the totality of things; ultimately this is the ideal
system contemplated by God. The completely adequate system of
ideas will ultimately be deducible from universally acceptable
“common notions” that are seen as evident by intuitive reason: these
are the axiomatic necessary truths and basic concepts of Spinoza’s
science and metaphysics that comprehend or constitute the logically
necessary and essential features of the universe.
94 Rationalism
An adequate idea gives an intrinsic mark of truth, as distinct from
the extrinsic mark whereby an idea merely corresponds to its object; a
completely adequate idea does not merely correspond to its ideatum; it
presents to us the true nature of, or understanding of, its ideatum. A
false idea is one that is inadequate; we know it corresponds to an
ideatum, but it will misrepresent, and fail to explain, the nature of that
ideatum, by failing to place the idea in the deductive system of
explanation which is constituted by a coherent system of ideas that
represents the true order of things. To have an adequate or true idea of
X is to understand X, which is to explain X, which is to know the
causes of X. The criterion of truth is given by features of ideas or
propositions themselves and the logical relation of proof between
them, and not by a mere comparison of ideas and the world; the
determination of what is true and what we know about the world is
available to us within the circle of ideas themselves in the form of
intuitions of reason giving “common notions” and necessary logical
deductions from these notions. At the level of completely adequate
ideas there turns out to be an exact agreement between ideas and
reality.
We can use a spatial perspectival example to understand the notion
of the completely adequate science. What I now see is in a way true
only from my perspective, my point of view; if I moved, or if I were
different biologically, what I see would be different—my view is in
this way particular. The aim of an adequate understanding is to see
things from no point of view; that is, to subtract all those features
which make my point of view mine or a mere point of view. The
intellect already provides us with such radically non-perspectival
truths: 2+2=4, for example. This is true from all points of view; its
truth is unconditional in not depending on any qualifying reference to
a perspective. Such is the nature of fully adequate ideas of the world;
these are found in rationally universally valid “common notions” and
deductions from them.
This rules out sense-perception as a means of attaining adequate
ideas of the world; we are to aim for an intellectual conception of the
world freed from the mixing of things in the world with their effect
upon us in terms of bodily processes. When we observe the sun, the
ideatum of the idea we have we confusedly think is the sun itself,
whereas the ideatum is really, in the sense of its physical correlate, that
bodily process corresponding to the perception of the sun, which is a
result of the effect of the sun on us. This is not a great problem
provided we come to understand the nature of our perceptions
themselves; in isolation the ideas of perception are not false, but may
become so—hence they are inadequate or untrue—when placed within
a wider explanatory context. A true, and thus adequate, idea, of the
sun as it is in itself will be approached by its deduction from other
ideas as part of a general science of physical things, the concepts of
Spinoza 95
which are grasped by the intellect, and this will replace the “false”,
inadequate, idea of sense-perception. The completely adequate system
of ideas places each idea in a totality of ideas such that the deductive
relation of the ideas represents the true order of causes in the world.
This is the world as understood by the intellect of God, who is
identical with the world.
Ultimately Spinoza’s completely adequate view of the world is sub
specie aeternitatis—the view from eternity, from outside time, from no
point of view. This is opposed to sub specie durationis—the view of
things as happening in time. God has such an eternal, non-temporal
view of the world; it should be our aim to participate in such a view.
We already have such non-temporal universal truths in mathematics
and geometry; it is senseless to apply time or duration to the truth
2+2=4; it is more than always true, its truth lies outside time altogether,
in eternity; the concept of duration has no application here at all.
Spinoza thinks that a true, hence completely adequate, explanation of
the world can be attained only through a view which is similarly sub
specie aeternitatis; the view outside time is the final step in ridding a
conception of all perspectives; one would then have the eternal,
necessary, a priori deductive explanation for everything. Some of these
truths we can grasp; but our finite minds enable us to grasp only a
small fraction of them.
There are three levels or kinds of knowledge. The first kind of
knowledge is sense-experience, the second kind of knowledge is
deductive reasoning, the third kind of knowledge is immediate
intuition of reason.
Sense-perceptions can be useful in giving us limited knowledge of
particular facts and in the forming of inductive generalizations. Our
finite minds cannot trace the infinity of causes that would give us fully
adequate ideas of the objects of sense-perception. Our finite minds
cannot cope with the infinite complexity of deducing truths concerning
finite modes (“A red book is on my desk”) all the way back to the
essence of God. Knowledge of the third kind, intuitions of reason, is
the highest form of understanding. There we not only have ideas
giving logical explanations by being related deductively to premises,
as in the second kind of knowledge, we also simply grasp the proof
complete in one intellectual act by seeing the rule in the instance. In
the case of sense-perceptions, we are presented with one inadequate,
fragmentary, logically unconnected idea after another (which is
correlated with inadequately understood states of the body) with no
real possibility of the order of presentation reflecting the true order of
causes. Sense-perception is not needed and cannot give knowledge of
the essence of things; in so far as we do not distinguish a thing from its
essence, we can deduce its nature from its definition.
Sense-perception can give knowledge that but not knowledge why,
which involves deducing the necessity of that perceived to be the case.
96 Rationalism
Nevertheless, sense-perception presents a low-level sort of knowledge
since it can satisfy what seem to be Spinoza’s three conditions for
knowledge that p:
(a) p corresponds to what is the case
(b) there is no reason to doubt that p (that is not to say p cannot be
doubted)
(c) there is a good reason to assert that p is the case (it is not a
guess).
Sense-experience as the ground for the assertion of either particular
facts or inductive generalizations seems to satisfy these conditions.
Knowledge in its highest senses of the second and third kind, which
involve deductive proof or logical necessity, clearly satisfies the above
conditions for knowledge, but to a higher degree.
The third kind of knowledge is the kind of understanding God has
of things in their totality derived from “common notions”. God’s view
of the world sub specie aeternitatis telescopes down the process of
deductive reasoning involved in comprehension of the totality of the
world to one intellectual “point”. Time is thus ultimately unreal from a
God’s-eye point of view. The ultimate explanation of the world lies
within the world; the world is fully explicable as a self-contained
system.
The general metaphysical conclusions are reflected in the Spinozian
response to the mind-body problem: ontological monism (a single
substance) is combined with a conceptual dualism (double-aspect). A
human being is viewed as mind or as body—these are two aspects of
the same thing; indeed, the ideatum of the mind is the human body.
This does not mean one is always conscious of one’s body; it alerts us
to a dual use of “idea of” in Spinoza. First, there is that derived from
ideas being expressions in thought of that which is expressed under
the attribute of extension; second there is the sense in which I have an
idea about some object. In the case of an idea of a table there is the first
meaning of the “idea of” the table, in the sense of the idea being an
expression in thought of some state of my body affected by the table
(that which may be involved in seeing the table); there is the second,
different, meaning of “idea of” in the sense of my idea being about the
table—its content or object is the table. In this second sense ideas are
said to be active and to exhibit intentionality: they point beyond
themselves to an intended object.
There can be no causal relation between mind and body; mind
concepts and body concepts are incommensurable so that logical
deductions, and hence causal laws, which included talk from both
ways of conceptualizing substance would be senseless. The relation
between the two systems of concepts is like that between two
autonomous languages which can say or express the same things each
in its different way. There is some relation between mind and body: it
Spinoza 97
is the correlation between determinate states of two attributes of one
substance. The complexity of thought of which a mind is capable is
therefore directly matched by the complexity of the body; a human
being is capable of complex thought processes, and this has its
correlate in the complexity of the human body. This means that
although every physical mode (ideatum) under the aspect of extension
has its corresponding idea, most things lack the necessary complexity
to be capable of conscious thought. Spinoza is not committed to stones
or chairs thinking; but the difference between them and us is only one
of great degree.
A human being is one kind of finite mode of the one infinite
substance. What gives meaning to the notion of any finite mode
having limited individuality is our conatus (striving, endeavour or
power): the endeavour to maintain its integrity or persist in being
against the effects of external causes. The nature or essence of a finite
mode is that without which it would cease to exist as what it is even
as a qualified individual, and would collapse under external causes.
In so far as the states of a thing are deducible from its nature or
essence, that is the conatus or power of that thing in self-preservation.
This will vary in degree and kind. The greater the conatus, the more
self-dependent it is and the more that through its essence, it expresses
power of self-preservation, power which is ultimately derived from
and expresses the power of the only truly independent individual,
God. Higher level finite modes such as organisms obviously exhibit
conatus: they try to persist in being what they are—a man, a dog—
with some degree of individuality. The greater our conatus the more
we realize our essence as rational beings; but this seems to produce a
conflict with our individuality, for we then have a view from which
we appreciate our connectedness with the whole of nature. No finite
mode can be ultimately self-explanatory of course, but the degree of
independence is determined by the balance between the derived
“active” (internal) explanation of its states and the “passive”
(external) explanation of its states.
A result of this is that no thing can be the cause of its own
destruction; the destruction of a thing is always through an external
cause. This is because the conatus of a thing is its essence, and its
essence revealed in a definition affirms what it is; thus in so far as a
thing is considered only in itself, in virtue of its essence, it cannot be
destroyed as that thing. This seems to make suicide impossible. But
Spinoza can answer that suicide is a case of being overwhelmed by
external causes. However, cases of rationally defensible self-sacrifice
complicate matters; the answer relates to Spinoza’s conception of
freedom as acting in accordance with universal rational principles.
Freedom does not consist in our being able to do otherwise than we
do; it is not contrasted with necessity; it is understood in opposition to
constraint. Everything that exists is necessary either by reason of its
98 Rationalism
essence or by reason of an external cause (another finite mode);
everything that does not exist is impossible either by reason of its
essence containing a contradiction, or for want of an external (efficient)
cause. The external chain of causation is ultimately necessary by
deriving from God’s essence; the impression we have of contingency is
merely the consequence of ignorance of causes. We are free in so far as
the explanation of what we do derives from our conative disposition to
behave in certain ways, as our essential natures meet each situation.
The exact nature of the conatus will vary between organisms. There is
nothing that is good or bad in itself; things are good or bad only in
relation to some conative disposition; things are good or bad for
someone or some kind of thing. Everything is free “in so far as it is in
itself’: that is, in so far as the explanation for what it does is derived
from its essence, which determines what it is. In this sense God is
absolutely free; not because what follows from His nature could be any
different from what it is—not because He could have “acted”
otherwise—but because God is totally self-determined, and thus totally
unconstrained. We are in a state of bondage in so far as we are the
slaves of external determinations and circumstances. This does not
mean we should live without emotion, but we should, in order to be
free, have active emotions following from reasoning; we should control
our passive emotions which are derived from external causes. In so far
as a man is externally caused, he acts under the influence of
inadequate ideas, failing to see how events must follow by logical
necessity from one another. The free man acts under the dictates of
reason, by the active causal determination of an internal logic; the
principles of reason are universal, thus in so far as we act because of
reason we make ourselves free in virtue of acting from causes
independent of particular circumstances.
This returns us to adequate ideas and their metaphysical connection
with Spinoza’s search for human happiness, contentment and
freedom. To understand this we have to remember that Spinoza
conflates logical and causal necessity. In so far as we entertain
adequate ideas, our ideas follow one another by their internal logic, a
logic that is independent of external causes. The explanation for the
occurrence of one idea, in so far as it is adequate, will be found in its
logical deduction from previous ideas; this gives a logical and causal
integrity, a self-sufficient, self-contained system based on universal
rational principles independent of external explanations and hence
external causes. There will be some bodily equivalent to this mental
aspect of human beings and in this sense we are free. What human
conatus ultimately seeks to preserve is this power of self-determination
itself. It reaches its highest degree when ideas are sub specie aeternitatis
because such ideas are absolutely necessary and universally true.
We are free when we act according to reason because the dictates of
reason are necessary, universal, categorical and thus independent of
Spinoza 99
context or particular situation. We act independently of contingent
particular external causes and circumstances if we act by reason: we
are then free.
Passive human emotions are controlled by reason to the highest
degree under the third kind of knowledge; for then the truth I grasp is
not an abstract deduction, but is intuited irresistibly in the particular
case; thereby it becomes not a truth I merely rationally accept, but one
that has force or power to effect changes in my emotional states. The
inference has force as well as validity. But since Spinoza is a strict
determinist, it is difficult to see what someone can do to bring about
the attitudes Spinoza thinks desirable; either one will be determined to
have them or one will not.
Our aim should be the attainment of a view of the world that is
detached and eternal. By striving for the completely adequate view
which is sub specie aeternitatis, of which only God is fully capable, one
comes to see the strict logical necessity of all that happens; all follows
from God’s immutable nature by logical necessity. We can thus
reconcile ourselves to the necessity of things. It no more makes sense
to hate a man who hits us than it makes sense to hate a tree that falls
on us; although in both cases this does not preclude our trying to do
anything about it, like getting out of the way—but we understand the
necessity of what happens through reason.
Although there seems nothing we can do to bring about human
happiness and peace of mind, they nevertheless consist in having a
certain attitude toward the world. The wise man engages in a life of
philosophical contemplation studying the rational and eternal: a life
of relative independence from the buffeting vicissitudes and
unreliability of particular circumstance, one which gives enduring
pleasure and grants peace of mind; the troubled mind is alleviated
when one views the world and events in one’s life sub specie
aeternitatis. The rational understanding that God is the ultimate
eternal cause of all things is what Spinoza calls the “intellectual love
of God”. To the extent that we entertain conceptions or ideas sub specie
aeternitatis, we free ourselves from the bondage of time, since such
conceptions are absolutely necessary and have no temporal reference;
and it is in this that our ultimate happiness lies; to the extent that we
do this, we participate in God’s eternal vision and the eternal
existence which is God’s existence.
Leibniz
Gottfried Wilhelm Leibniz (1646–1716) was the son of a Professor of
Moral Philosophy at the University of Leipzig. Leibniz’s early
education, with a Lutheran religious background, would have
involved the study of Latin, Greek, theology, and Aristotelian logic.
100 Rationalism
He graduated from the University of Leipzig in 1663, and gained his
doctorate in 1666 from the University of Altdorf near Nuremberg. He
began his employment with the Baron of Boineburg who was first
minister to the Elector and Archbishop of Mainz, but in 1667,
following the death of Boineburg, he moved into the service of the
Duke of Brunswick in Hanover. One of his major duties was that of
librarian. Between 1672 and 1676, Leibniz was on a diplomatic
mission in Paris, which was at that time the centre of European
intellectual activity. There he met important thinkers such as
Malebranche, Arnauld (with whom Leibniz corresponded
extensively), and the physicist Huygens. Huygens, recognizing the
talent of Leibniz, set about improving Leibniz’s mathematical
knowledge. In Paris Leibniz would have been fully apprised of
Cartesian philosophy. In 1673 Leibniz visited London, where he met
the chemist Boyle and the Secretary of the Royal Society, Oldenburg;
on this visit he also became acquainted with the materialism of
Hobbes. In 1676 Leibniz went to Amsterdam in the hope that he
would find, in the work of Spinoza, answers to some of the problems
he perceived in Cartesian philosophy. He spent a month there; some
of the time was spent reading Spinoza’s Ethics, some in discussion
with the ailing Spinoza.
There were many influences on Leibniz’s philosophy; apart from
those already mentioned, he was impressed by Plato’s Phaedo and
Theaetetus and well acquainted with scholastic philosophy (derived
from Aristotle)—for example the notion of substantial forms.
Leibniz was a stupendous polymath, active in almost every
imaginable area of inquiry, from geology and mining engineering to
philosophy, mathematics and logic. He was indeed a mathematician of
genius, and discovered independently, and simultaneously with
Newton, the infinitesimal calculus. His fertility of mind left an array of
unfinished projects. Leibniz was a man capable of bouts of intense
intellectual activity; he is said to have spent several days at a time
sitting working at his desk—even sleeping in his chair. He suffered
from intellectual isolation in Hanover, where he spent most of his time.
During Leibniz’s lifetime there were few academic journals, and letters
were the chief means of exchanging ideas. Leibniz’s correspondence is
massive involving over 1,000 correspondents; in any single year he
frequently wrote to more than 150 people. He hoped that one day all
reasoning in various fields of inquiry could be united in one system, a
universal calculus of all reasoning, which would eliminate fruitless
disputes; answers to disagreements could be settled simply by
calculation.
Leibniz never married; he proposed, but the woman hesitated long
enough for him to think better of it. He was of medium height, with
sharply intelligent eyes; he had broad shoulders, but stooped and had
weak lungs. The last years of his life were ones of loneliness and
Leibniz 101
neglect. No member of the House of Brunswick bothered to attend his
funeral.
The philosophy of Leibniz is not like a building based on
unshakable foundations, it is more like a platform kept in balance by
constant adjustments to the weight put upon various fundamental
logical principles. These basic principles in Leibniz’s philosophy are
logically interconnected; and for this reason it has no definitive
starting place.
In Leibniz’s philosophy there is an intimate connection between
metaphysics and the fundamental nature of logic. This is a view which
has ancestors and heirs: it suggests that conclusions in and about the
basic structures of logic lay bare the basic structures of the world.
Certain important truths derived from logic are seen by Leibniz as
having consequences for any attempt to explain the fundamental nature
of the world which is studied in metaphysics. Probably the best
approach to Leibniz is to state what the basic truths of his thinking are,
and then proceed to see how he uses them to solve certain
philosophical problems. There are five major basic principles in the
philosophy of Leibniz.
(1) The predicate-in-subject principle: the nature of the proposition
This “inesse principle” holds that, in all true propositions that
which is predicated of a subject is contained within the concept of
the subject. All propositions are ultimately reducible to the
subject-predicate form. This gives a theory of truth in which in all
and only true propositions the predicates are contained in the
concept of the subject; all analytic propositions are true and all
true propositions are analytic.
(2) The principle of non-contradiction
This asserts that propositions p and not-p cannot both be true,
and that any proposition that implies a contradiction is
necessarily false; and any proposition whose denial implies a
contradiction is necessarily true.
(3) The identity of indiscernibles
This says that there cannot be two entities which have all their
properties in common. Entities which are identical in their lists of
qualities are the same entity; they are indiscernible.
(4) The principle of sufficient reason
There must be a sufficient reason (complete explanation) why
everything in the world is just so and not otherwise, even if we
cannot know what that reason is. There are to be admitted no
inexplicable truths about the world.
(5) The principle of perfection
Those propositions which describe the most perfect world—the
best of all possible worlds—are true. This amounts to saying that
God creates the most perfect world He can and it involves the
102 Rationalism
notion that the most perfect world is “simplest in hypotheses and
richest in phenomena”; God maximizes both plenitude or variety
of phenomena and order or simplicity of explanatory hypotheses.
Leibniz makes a fundamental distinction in his logic between “truths
of reason” (necessary or eternal truths) and “truths of fact” (contingent
truths). Truths of reason are those truths which, by a finite analysis,
show that their denial produces a contradiction, that is, an assertion of
(p and not-p). To assert a necessary truth is, on analysis, to assert an
identity. The analysis is a process of definitional substitution: for
example, 1+1 being substituted by definition for 2. Thus, to assert
2+2=4 is ultimately to assert 1+1+1+1=1+1+1+1; to deny 2+2=4 would
obviously produce the contradiction that 1+1+1+1¹1+1+1+1. To allow
that (p and not-p) could be true would be to threaten the possibility of
all meaningful talk, since we would fail to make the most basic
distinction required for any such talk, that between assertion and
denial. The assertion that p, and its denial, not-p, cannot
simultaneously be true. Truths of fact do not, if denied, entail a
contradiction; to deny “Alan is wearing a green shirt” does not seem to
involve any contradiction. Truths of reason are necessary truths in that
they could not be otherwise; they must be true; in any possible world
these truths must hold. Truths of fact are contingent, they could have
been otherwise; they might not have been true; there could be possible
worlds in which these truths do not hold. Leibniz accepts that truths of
reason can be known independently of any sense-experience, a priori;
whereas truths of fact can be known only through examining the
world, a posteriori.
Leibniz argues that although the meanings of the terms of a
language may to some degree be a matter of arbitrary definition, this
does not mean that either the contingent or the necessary truths
expressed in a language are dependent on contingent facts about
language; the only thing that is contingent is the particular form the
expression of such truths takes, not the logical status of the truths
themselves as either necessary or contingent. This distinction between
the truth expressed and the form of expression of a truth is particularly
important in the case of necessary truths, which he sees as eternal and
objective.
At first sight Leibniz’s philosophy can seem obviously false; some of
the basic principles listed above, far from being universal truths, seem
plainly false when applied to the world. For example, surely it is
possible (probable even) to have two identical objects? Surely it is far
from obvious that all truths are true in virtue of the predicates being
contained in the concept of their subject? It becomes clear, however,
that what Leibniz is applying the basic principles to is the underlying
structure of reality; this reality is a metaphysical reality that stands
behind the world as it appears; it is grasped by the intellect by an
Leibniz 103
inexorable logic as the way the world is and must (necessarily) be at its
most fundamental level if the most basic truths of reason are to hold. If
we accept Leibniz’s basic principles, then he argues that the nature of
reality is not how it appears to be, but really quite different. This is to
characterize substance, or the really real.
The examination of this underlying structure can begin by
considering substance. In Cartesian philosophy there are two “created
substances”: mind and matter. In Spinoza there is just a single
substance: “God or Nature”. What the Cartesian view seems to leave
out is an account of the individual, or identity. As we look around us it
seems obvious that some things are separate individuals capable of
remaining the same individual kind of thing while undergoing change,
whereas other things are merely “heaps” or collections of qualities
with no intrinsic unity. Compare a pile of pebbles, which is not a kind
of thing, with a crab found on a beach. Scholastic philosophy, derived
from Aristotle, had sought to take account of this through the notion of
“substantial forms”. Thus, the soul is the substantial form of the body,
for whatever may befall someone, so long as that person exists the soul
remains the same soul; without some such notion we cannot make
sense of someone being young and that same someone being old; any
change would, strictly speaking, produce a new entity, not the same
entity with a new property. The notion of individuals here aims to do
justice to the distinction we make between things which have an
intrinsic organic unity as kinds of thing, such as men and dogs have,
and things which are mere heaps of stuff, such as a pile of pebbles. But
in pursuing things that are true unities or true individuals, Leibniz
moves a long way beyond the Aristotelian commonsense substantial
forms which are natural kinds such as man or horse.
In the case of physical things the identification of real unities (things
that remain the same kind through change) is relatively unimportant; it
is possible to say that all physical things are portions of a single
extended substance. In the case of the person as mind, individuality
becomes of pressing concern; identity in this case is of vital
importance. Spinoza challenges the Cartesians to provide a principle
of individuating minds; if the only essential attribute of mind is
thought, it is difficult to see how there can be a plurality of distinct
mental substances or minds differentiated by essence. Spinoza’s
conclusion is to deny any sense of individuality as substances to either
physical things or minds; they have a limited individuality at the level
of modes, but are all modifications (modes) of the one substance,
without any ultimate substantial independent unity of their own.
Leibniz sides with the Cartesians in agreeing to a plurality of
substantial individuals, but makes the claim all-encompassing; for
anything in the world to be real, there must be at some deep level true
unities or individuals: completely autonomous entities.
This brings us to what Leibniz calls the “labyrinth of the
104 Rationalism
composition of the continuum”, which leads him to his conception of
substance, and thus to the ultimate nature of reality. Leibniz has the
same general conditions for substance as were found in Descartes and
Spinoza: that in considering the nature of the world and our
explanations of that world, we must, if we are not to enter into an
infinite regress, reach something which is (a) ontologically
independent or autonomous, and (b) self-explanatory. Substance is the
permanent stuff which stands behind appearances which are
secondary or derivative. Things appear to change in the world; the
explanation of these changes comes to an end at something that
remains the same, otherwise the explanation would go on for ever.
What is fully real is completely independent and self-explanatory; the
fully real is the ultimate logically unchanging constituent of change
and plurality. The explanation for anything, if we are not to regress
infinitely by always having to look to another thing for an explanation
outside that which we are explaining, must end in something that is
fully causally autonomous and fully the explanation for its own states.
Spinoza says that within true substance must lie the full explanation
of not only its nature but also its existence; and he contends that there
can only be one substance, and that is the totality of reality. Leibniz
demands not that a true substance should contain within itself the
reason for its own existence, but only that it should contain the reason
for its entire nature, that is, all its states.
In Leibniz’s view, in giving a rational account of the world, we must
give an account of what it is that is the ultimate constituent of reality;
that which does not alter through natural change, but is, rather, the
constituent of that change and, to avoid a regress of ontological
dependence, is not itself subject to natural alteration. Leibniz is
searching for that which, with respect to all natural means of change,
cannot be destroyed and is without parts, and so is indivisible; the
aggregation and dissolution of aggregates of such entities constitute all
perceived change and plurality. Leibniz identifies this true substance
as a monad (a word which derives from Greek meaning “unit alone”).
Ultimately we must reach such really independent substantial unities,
and each one is a unique kind, not merely a collection of parts; they do
not change by natural means, but exist or do not exist all at once. They
are perfectly determinate. Such entities are the only way to ensure that
we have identified genuine substance; something not ontologically or
rationally dependent on any further constituent elements because its
existence is all or nothing; each is a unique kind that either exists
complete, or ceases to exist completely; as a unique kind, if it changed
in any detail, it would cease to exist altogether. The ultimate
constituents of reality are an infinity of unique individual kinds called
monads.
The “labyrinth of the continuum” problem involves considering the
ultimate nature of the world, in particular the nature of matter. If the
Leibniz 105
world is a continuous whole, then its parts would seem to be unreal
arbitrary divisions; if, on the other hand, the parts are real, then the
world is not a continuum, but a collection of unrelated discontinuous
parts. The aim is to reconcile real wholes which are continuous with
real parts that are indivisible. We can consider this as the relation of
wholes to parts, and present it as a dilemma: extended whole things
are either finitely or infinitely divisible. If extended wholes are finitely
divisible, we reach atoms, which are real parts in being indivisible; but
then the whole that they make up becomes unreal because it is
discontinuous, a mere arbitrary heap of atoms between which there is
no intrinsic connection. The suggestion that there are, in addition,
forces between the atoms runs counter to atoms being the ultimate
constituents of reality in terms of which all else is explained and
constituted. Nor can the coherence of atoms be explained through an
interlocking system of hooks and eyes; anything capable of having
hooks and eyes would itself be capable of having parts in need of some
internal principle of cohesion. If extended wholes are infinitely
divisible, as the Cartesians thought, then the parts are unreal because
we have an infinite regress of divisibility; and this gives us a whole
with unreal parts. Leibniz argues, against physical atomism, that
anything extended must be divisible in principle. The solution in this
search for a substance which reconciles the real continuity of the world
with the real indivisibility of parts is to exclude extension from among
the qualities ascribed to substances: the most basic entities of the
world. Anything that can be divided would cease to exist as one thing,
and thus would be subject to external causes, and could not be a true
substance.
Ultimate substances are monads which have no extension; they are
purely qualitative (intensive), and have no quantitative (extensive)
properties; they are independent in all respects except for their
existence, for which they depend on God, and they are simple in being
without parts; they can be destroyed only by total annihilation (or
miracle), not natural change, for natural change is the constantly
changing aggregation of monads. This notion of substance is derived
by analogy from the non-spatial “I” or “soul”, for it is this that remains
the same through all the changes in our lives, so that we retain our
identity. Monads are the unchanging constituents of all natural change,
in that anything that happens in a monad is a product of its own
indwelling nature. There is an infinity of monads, each of which is a
unique individual kind in virtue of being identified by a unique
infinite list of predicates giving all its properties.
Leibniz conjoins the contingency of existence with the principle of
sufficient reason to give a proof of the existence of God. For every fact
or truth there must be a sufficient reason. Granted that something
exists, there must be a reason why something exists rather than
nothing; this reason cannot lie within the series of existing finite
106 Rationalism
things, for we would never among existing things find something
whose existence did not itself require further explanation. We must
find such a reason outside the world in a logically or metaphysically
necessary being—a being whose existence is not contingent—which is
the sufficient reason for its own existence. Another way of putting this
is to say that although the state of A is explained sufficiently by
reference to state B, so that we can explain this or that state from
within contingent events within the world, we cannot from within the
world of things with states explain why there are things with states at
all, why there are any states whatsoever. This argument relies on the
principle of sufficient reason having unlimited application; we might
instead be prepared to argue that “Why is there something rather than
nothing?” or “Why should there be anything at all?” is a question
which does not have an answer; it is a brute fact beyond which we
cannot go.
The world as it appears to us as matter in space and time is a set of
“well-founded phenomena” (phenomena bene fundata); the world as it
appears is our misperception of qualitative changes in the world of
monads; the world of appearances is secondary, and derived from the
underlying reality of an infinity of self-subsistent, self-explanatory
monads which are without parts. This solves the problem of
reconciling the continuity of the whole with the indivisible (simple)
reality of the parts: the whole is a plenum or continuum in virtue of
the adjacent monads differing infinitesimally from each other, and the
parts are real in that monads, being unextended, are indivisible.
Given the conception of true substance as monads, we can now
begin to apply to the world the basic principles of Leibniz’s
philosophy listed above. Monads, as true substances, must—except for
their dependence on God for their existence—be independent of all
other things, and must be completely self-explanatory; monads can be
both these things by all that is true of them being true analytically.
Each monad is its own complete concept in that it contains within its
essence the list of all the predicates, past, present and future, which are
true of that individual monad, apart from its existence. God is the only
substance that exists in conjunction with all possible worlds, for unlike
all other substances, that God exists is analytically part of His complete
concept or essence. Although the existence of all monads except God is
contingent, Leibniz sees no sense in the distinction between accidental
and essential properties of substantial individuals; all properties are
equally essential in being deducible from the complete concept of the
monad; and substantial individuals are individuated only through
considering their whole being or complete concept.
Leibniz thinks that Spinoza confuses determinism and extreme
necessitarianism. While, according to the principle of sufficient reason,
everything in the world must be fully determined—there must be
something which is sufficiently the reason for the way it is —this does
Leibniz 107
not mean that this or any other deterministic world is the only possible
deterministic world. That would involve confusing necessary and
contingent truths. Leibniz makes the distinction, and derives it from
the idea that all propositions are ultimately reducible to the subjectpredicate
form; a true proposition is such that the predicate is
contained in the concept of the subject.
Necessary truths (truths of reason), such as 2+2=4, are those whose
denial, in itself, implies a contradiction; they are unconditionally true
in all possible worlds; they have an absolute or metaphysical necessity.
Contingent truths (truths of fact) are those whose denial does not in
itself imply a logical contradiction; they are, however, conditionally or
hypothetically necessary when they are logically implied by some
other true proposition from which it would therefore be a
contradiction to deny they follow. Contingent truths (such as “Caesar
crossed the Rubicon”) are conditionally necessary truths, given that the
individual monadic substance (Caesar), of whom the truths are
predicated (crossed the Rubicon), exists. A proposition is conditionally
necessary (contingent) if its denial is not a contradiction in itself, but
there is some other proposition from which it logically follows. A
proposition is unconditionally necessary if, by finite analysis, its denial
is a contradiction in itself.
Unconditionally necessary truths (truths of reason) hold across all
possible worlds, and cannot determine which of the infinity of possible
worlds is actual. The principle of non-contradiction is sufficient to
account for metaphysically necessary truths, although Leibniz also
thinks such truths are eternal objective truths in being in the mind of
God. But in the case of contingent truths a further reason is needed to
account for why certain truths are actualized and not others. Truths are
contingent because God was not ultimately logically compelled by the
principle of non-contradiction to actualize those truths. The further
sufficient reason for contingent truths—what among the non-necessary
possibilities God actualizes—is found in the principle of perfection.
God creates the best, or most perfect, of possible worlds from a choice
of infinite possible worlds; the actual world is the one that maximizes
copossibles. All possible truths strive to be actual truths in that they
will be actual truths if their being true does not contradict the
actualization of some other possible truth. The principle of perfection
is the general test for truths of fact: the actual world is the one that
maximizes both plentiful variety (diversity) and order (simplest laws).
Existence is taken to be a perfection by Leibniz. All truths ultimately
refer to truths about the underlying monads, so all truths are
eventually analytic in that the predicates are contained in their subject;
but in the case of contingent truths this analysis is infinite, because to
show analyticity is equivalent to showing how that truth fits into the
most perfect world.
The principle of perfection gives us a criterion of truth for choosing
108 Rationalism
scientific laws: we should choose the law that explains the greatest
variety of phenomena with the greatest unifying simplicity.
Being true substances, monads are their own complete explanation,
except for the explanation of their existence; thus everything that is
true of them is true analytically; they are fully independent; so there
can be no causal interaction between them. Nevertheless, things in
nature appear to interact. This appearance is accounted for by
Leibniz’s notion of pre-established harmony. Leibniz denies causal
relations involving necessary connections between phenomena or
between the monads; he replaces these with pre-established harmony
and causal laws with functional relationships; in science we are simply
concerned with the determinate way one phenomenon varies in
relation to another. It is these functional relations that constitute laws
of nature, not some mysterious further notion of necessary connection.
Just as the existence of any monad is always contingent, and there is
an infinity of possible worlds, so there is an infinity of possible laws or
orders of nature. The only true causes, apart from God, in the sense of
producing deductive explanations, are the states of the monads
derived from within each monad itself.
Each monad is completely self-contained, but in a more or less
confused way every monad mirrors the entire universe. The mirroring
of the universe gives each monad a unique point of view; these
constitute active states of the monads which are “perceptions”; the
tendency to change between these perceptions is termed
“apperception”. The spontaneity of changing states of the monads
reflects Leibniz’s concern for dynamics; that an essential property of
substance must be force or activity, contrary to the inert extended
matter of Descartes. The monads have “no windows” through which
anything can come in or go out; monads are substances and there can
be no interaction between substances. God’s initial choice of what set
of monads to create arranges things so that the subsequent states of the
monads are perfectly coordinated or harmonized in accordance with
certain laws. This is analogous to two clocks being set at the same time:
they always strike correctly together at twelve o’clock and at all other
times on the hour even though they do not interact. God, in choosing
this world, arranges a perfect coordination of all its monadic elements.
Each monad has within it an active force whereby its states unfold.
This harmonious coordination of the monads involves a mirroring by
each monad of the states of all the other monads, which means that a
change in any one monad would entail a completely different
universe, for adjustments would have to be made in the systematic
arrangement everywhere else. The universe is a plenum; the plenum of
space corresponds to the infinitesimal qualitative differences between
monads which are perfectly compacted.
The world as it appears to us in space and time is a set of “wellfounded
phenomena” rather than a mere illusion; that is, the world of
Leibniz 109
appearances is systematically underpinned by states of the monads.
Appearances are correlated with something that is ultimately real.
Great distances in space are correlated with great qualitative
differences between monads, small distances with the reverse. Time is
correlated with our perceiving the unfolding of the states of the
monads. All apparent relations are reducible to truths about individual
monads. So we can say that the relation of A being heavier than B is
reducible to a truth about A weighing five tonnes and a truth about B
weighing one tonne.
We can now see why the identity of indiscernibles applies
universally, as Leibniz suggests. Leibniz’s principles apply to the
ultimate nature of the world, not to things as they merely appear. It
may be suggested that we could have two substances with identical
sets of true predicates, but at different places in space. But space, as
well as time, is itself something derived from truths predicated of the
monads. Once we see that all true predicates describing all states
whatsoever are contained within the ultimate monadic elements in the
universe, we see that there could not be two substances with identical
lists of predicates; there would be nothing left in virtue of which they
could be distinguished.
Leibniz’s view of the world can be summarized as follows. All
reality is made up of an infinity of soul-like monads; these are true
substances; they are ontologically independent of everything except
God, as they depend on Him for their existence, and no two monads
are alike. They are independent in the sense that all that is true of them
is deducible from their full concept or essential nature. Logically
necessary truths are true of all possible worlds in virtue of the
principle of non-contradiction alone. Only God is such that a denial of
His existence would be a contradiction; the existence of all other things
is contingent. Each monad when it comes into existence goes from
being an unactualized possibility to being an actualized possibility. But
given that God chooses to create particular monads (basic substantial
individuals), everything proceeds from the complete conception of
those individuals with necessity. Thus some truths are contingent
because, although given the creation of individual A all that happens
to A follows with necessity, it is only hypothetical necessity, since the
creation of A was not itself necessary.
The monads actualized are the reality that underlies appearances
which are systematically related to those monads so that the
appearances are well-founded phenomena. We explain the appearance
of causation and causal laws between phenomena, which all derive
from monads, by there being an analogue of strict rules governing the
non-causal coordination of the states of the monads.
God cannot choose what is impossible, and any universe must
include what is necessary; but among contingent truths—those truths
that are neither necessary nor impossible—God chooses from among
110 Rationalism
the possible, pure essences that are not actualized. There must,
however, be a sufficient reason for what God chooses if the universe is
to be fully rationally explicable; the reason why God chooses to
actualize some contingent possibilities rather than others cannot be
found in the principle of non-contradiction, since their nonactualization
would not imply a contradiction; the sufficient reason is
derived from the goodness of God, which means that, from an infinity
of possible worlds, He chooses the best of all possible worlds; a world
of maximum plenitude or variety tempered with greatest order or
simplicity of explanation.
It should not be supposed from Leibniz’s talk of soul-like monads
inhabiting everything that everything is thereby conscious.
Nevertheless, the distinction between different levels of monads is a
matter of degree and is dependent on their level of activity and the
clarity of their perceptions. It is in virtue of these factors being at a
high level in our case that we have the capacity for reason.
We are monads. The human body is a collection of monads which is
dominated by the powerful monad of the human mind: the “I” in us.
Leibniz’s doctrine of pre-established harmony solves the Cartesian
mind-body interaction problem; there is now no mystery concerning
interaction for it is only an appearance, but one that is well-founded
in the coordination of the monads. The appearance of mind-body
interaction is the coordination of the mind-monad and the bodymonads,
and this is just a special case of monad harmonization. There
is no more difficulty in explaining this than there is the coordination
between any other monads in the universe; God so arranges things
from their inception. The monads that correspond to the telephone
ringing are perfectly harmonized with the monad which is myself
having the experience of the telephone ringing, without the
experience of the ringing being caused by the ringing itself. The
intimate nature of the relation between the mind/self-monad and its
body-monads, is accounted for by the special characteristics of my
perceptions in relation to my body-monads. I am a structured
aggregate of monads, structured by the degree of activity and clarity
of perception of the monads. The dominant monad is that which has
the greatest degree of activity and clarity. Leibniz distinguishes three
levels of monads: self-conscious monads; conscious monads;
unconscious or bare monads.
A remaining question concerns human freedom. The notion of
human freedom in the sense of choosing otherwise at a particular
moment seems irreconcilable with all truths concerning substantial
individuals, such as particular people, being analytic truths.
Although the predicates true of an existing individual are only
hypothetically necessary, since they depend upon God’s original
decree to create that individual of which the predicates are true, this
does not seem sufficient for freedom. It makes all that I do contingent
Leibniz 111
in the sense that there is no logical contradiction in supposing that
the specific individual that is me might not have been created at all to
do what I do. But, given God’s decision to actualize the possible pure
essence A1
, and thereby create monad A1
in particular, then its states,
(a, b, c…) follow necessarily or deductively from the complete
concept of A1
. The existence of monad A1
is itself contingent—it is not
contradictory to deny that A1
was brought into being or actualized—
so any particular state of A1
, say c, is contingent in that “not-A1
c” is
not a logical contradiction. There are possible worlds in which A1
c
might not be true because A1
might not have been actualized—
brought into existence—at all, but instead A2
. But we do not say that
people are free if it is a mere logical possibility that what they do
might not have been done because they may not have existed at all.
When God decides to create an individual monad A, this means
creating the complete concept from which all truths predicated of the
subject A follow deductively from analysis of—are contained in—the
concept of that subject; thus to change any of these truths would be
to change the complete concept and thereby destroy that individual
as that particular individual and create another individual. It seems
that I could only be free by controlling my complete concept; but only
God has this control at the inception of that monad. All that is true
of—happens to—an individual in total defines that individual. That
Leibniz died in 1716 is a truth that follows necessarily, given the
initial creation of that particular individual, that Leibniz had to die in
1716; if this had not happened, we must be talking of a different
individual.
A worrying question remains for Leibniz, connected with the
problem of freedom. Does the inesse (predicate-in-subject) principle
apply to God? Does whatever God does follow deductively from His
complete concept, including His decrees as to which world to create?
If this is so, then the distinction between necessary and contingent
truths is in danger of collapsing, because God’s decree to create the
most perfect world itself follows deductively from God’s complete
concept; and then what follows could not be otherwise unless God
ceased to be God, destroying His own complete concept. It would
then be a logical contradiction to suppose God could have chosen
otherwise. This threatens a return to Spinoza’s extreme
necessitarianism.
Leibniz is a rationalist in the sense that he thinks reason can grasp
the true nature of reality that lies behind appearances; he is also a
rationalist in the sense that it ought in principle to be possible to deduce
all the states of the world from an analysis of the complete concepts of
actualized monadic substances. This a priori analysis is also infinite,
and not completable by human beings, and moreover refers to an
intelligible reality that lies behind appearances and accounts for those
appearances, not to the appearances themselves. However, Leibniz’s
112 Rationalism
metaphysics provides only a framework of principles which are vastly
too general to allow the deduction of specific scientific laws; and in
this sense Leibniz is an empiricist; we can discover specific scientific
laws concerning the connection and order of appearances only from
observation and experimentation.
Leibniz 113
continued to ...