The Presocratics were 6th and 5th century BCE Greek thinkers who introduced a new way of inquiring into the world and the place of human beings in it. They were focused on nature, and introduced (sometimes rather simplistic) principles to explain phenomena.
What do we know of the general character of Presocratic thought? We have very little textual material about them, and most of it is from secondary sources (Aristotle for instance: He wrote about them, and quoted passages from earlier philosophers.) The two greatest representatives, Heraclitus and Parmenides, commented on the nature of change in general, or on the observation that everything that exists converges in one respect: it "is," it has being, and in this regard, there is unity in being as such.
Pre-Socratics also discuss other ideas:
Atomism: Leucippus and Democritus: Atomism. Unchanging elements of reality. (5th Century BC)
Paradoxes: Split between being/thought. Zeno, Eleatic School: Creates paradoxes of movement and time. Zeno is the successor of Parmenides.
Here are some of the famous fragments from Heraclitus. (See a complete list here. Numbers in brackets refer to the Fragments. There are only about 129 total sentences preserved.)
(10) Nature loves to hide.
(32) The sun is new every day.
(49) In the same river, we both step and do not step, we are and we are not.
(56) What we saw and grasped, that we leave behind; but what we did not see and did not grasp, that we bring.
(66) The bow is called life, but its work is death.
(67) Mortals are immortals and immortals are mortals, the one. Living the others' death and dying the others' life.
(68) For it is death to souls to become water, and death to water to become earth. But water comes from earth; and from water, soul.
(69) The way up and the way down is one and the same.
He "opens the gate:" What appears as a question for the first time in history is this: What is the nexus between being as truth, the position of the subject, and discourse?
The main text that is preserved from Parmenides is a poem, written down in the 6th century CE by Simplicius from unknown sources. Therefore, the partial text available to us was written almost a millennium after its creation.
The poem depicts a hero’s ascension leading him to a deity who reveals to him the “way of truth,” that of Being. This “revelation” is the poem’s doctrinal core. But this ascension is more than an accessory element to the poem because it is the sign of the ascension of the discourse itself. The medium is here part of the message. This is important for understanding the poem. Although some speak of a “Parmenidian” conception of Being, the poem speaks of a goddess' perspective on Being. Here is the first fragment of the poem:
"You must hear about all things [panta],
[1] both the still heart of persuasive truth and
[2] the opinions of mortals, in which there is no true conviction.
[3] But even so, these things you shall learn: how opinions can have real existence, passing the whole way through all things.”
Parmenides' Argument:
(1) Only that which can be thought can be.
(2) Non-being cannot be thought. Therefore:
(3) Non-being cannot be.
Counterpoint: "Nothing is, if not insofar as it is said that it is.”
Is it based on a religious sentiment?
“…Being is without beginning and indestructible; it is universal, existing alone, immovable and without end; nor ever was it nor will it be, since it now is, altogether, one, and continuous.” The perspective that expresses itself in these words views reality as a whole; against our experience of a continuously changing world, he posits a reality that is undivided, infinite, and changeless, without beginning and end and without causation, a reality that we never leave and from which we are not separate.
At first hand, the philosophical position of Parmenides may seem far off, highly stylized, and ignorant towards the intermediary dimension of language when it comes to the relation between thought and reality. This impression is false: Ludwig Wittgenstein returned again and again throughout his career to questions that follow directly from Parmenides: what is the truth or falsehood of positive and negative judgments?
Here are some examples:
What is the falsehood of a simple positive judgment? Wittgenstein writes: "How can one think what is not the case? If I think King’s College is on fire when it is not on fire, the fact of its being on fire does not exist. Then how can I think it? (Wittgenstein, The Blue and Brown Books (Oxford: Blackwell, 1969), p,31)
In comparison, Wittgenstein also asks about the truth of a simple negative judgment: "It is the mystery of negation: This is not how things are, and yet we can say how things are not." (Wittgenstein, Notebooks 1914–1916, trans. Elizabeth Anscombe (Oxford: Blackwell, 1979), 30.)
What is the logical validity of certain inferences? When it comes to the Parmenidean syllogisms of thinking and being, what are the forms of validity? Here are two examples of such syllogisms:
(1) A thinks p (1*) A thinks not-p
(2) not-p (p is not the case) (2*) not-p (p is not the case)
(3) A falsely thinks p (3*) A truly thinks not-p
Which side, left or right, is correct? Or are they both right? Where are the gaps between premises and conclusion on either side?
Wittgenstein understood that there is a problem, which he tried to emphasize again and again with examples in his later writings.
The Infinite, Apeiron: Anaximander of Miletus, the first author of whose writings we still have a conserved sentence fragment, claimed that the basic principle is the infinite (or the undefined, apeiron):
Of those who hold that the first principle is one, moving, and infinite, Anaximander, son of Praxiades, a Milesian, who was a successor and pupil of Thales, said that the infinite is principle and element of the things that exist. He was the first to introduce this word principle. He says that it is neither water nor any other of the so-called elements but some different infinite nature, from which all the heavens and the worlds in them come into being. And the things from which existing things come into being are also the things into which they are destroyed, in accordance with what must be. For they give justice and reparation to one another for their injustice in accordance with the arrangement of time (he speaks of them in this way in somewhat poetical words).
If the basic nature of reality is that it is unlimited, then all things that exist must be limitations existing in the basic nature of reality. Dialectical thinking is already implicitly present in these early texts.
Protagoras and Gorgias: Man is the measure of all things. "Any given thing is to me such as it appears to me, and is to you such as it appears to you." (Plato, summarizing Sophists.) Anthropocentric relativism. Diametrical opposite to Parmenides.
Gorgias: Using eristic arguments that are similar to Zeno’s, Gorgias argued three things: (1) nothing is; (2) even if something is, it is unknowable; and (3) if it is unknowable, it is impossible to explain to someone.
Gorgias concludes that if neither Being nor Nonbeing exist, then nothing exists. Gorgias acknowledges that his discourse may only be sophistic (but then again, so are all discourses!) and since he argues that even if Being did exist (which he has already rejected) it would remain “unknowable and incomprehensible to man.” The fact is, argues Gorgias, that there is a gap that separates Being from thought.
Even if Being/Truth could be apprehended, it could not be communicated.
Being remains forever elusive. All human discourse is limited by rhetoric and opinion.
Human discourse, according to the Sophists, is characterized by the fact that it has no access to Being, but only to appearance.
Therefore, its essential elements are rhetoric and opinion rather than science and truth.