The Oxford English Dictionary defines real as: "Having an objective existence; actually existing physically as a thing, substantial; not imaginary."
Its antonym unreal is defined by Merriam-Webster as "lacking in reality, substance, or genuineness"; "not real and existing only in the imagination."
“Reality is that which, when you stop believing in it, doesn't go away.”
Philip K. Dick
Bats emit and detect ultrasounds for locating preys and communication among them. We humans can not ear their noises, and it is not because they are faint, it is because our ears are not able to react to them.
Our senses can react to the world when they are properly stimulated:
the stimulus is within a certain range.
the stimulus has a certain intensity.
But outside of those ranges and below those intensities, our senses do not perceive the reality.
Sharks and other animals are sensitive to electricity. They can detect electrical signals.
How can they do it?
Why do they do it? Is there an evolutionary advantage?
Some bird species are sensitive to magnetism. They can detect magnetic fields, Earth's magnetic field in particular.
How can they do it?
Why do they do it? Is there an evolutionary advantage?
We humans can't detect electricity nor magnetism. It is not a matter of range or intensity of the estimulus. It is because we are insensitive to these realities.
It is not only that our senses are limited in range and intensity, or that we are completely insensitive to some realities, but also that our senses can deceive us:
Are squares A and B of the same shade of grey? Click to see the answer...
It is not only that our senses can sometimes deceive us, it is also that the sensory information is influenced by memories and previous knowledge, by expectations and motivation, etc. So, our perception depends on many factors in addition of the actual stimuli:
Sugar is sweet, Is sweetness in the sugar? Where exactly can it be?
Salt tastes salty. Is saltiness a property of sodium clorhide crystals? Where exactly could it be located?
Since sugar does not taste salty and salt does not taste sweet, flavors must somehow be in them, but how exactly?
Are the scents we perceive in the objects that we smell? It looks like it, since we smell something when we approach our noses.
Are the colors we see in the objetcs? It certainly looks like it. We see colors in front of us.
Thanks to our sense of touch we perceive that some objects are hot and others cold.
What is temperature, according to physics? Are molecules or atoms hot or cold?
Are pains and pleasures real?
Are love, hate and all the other emotions and feelings real?
Do they exist by themselves of depend on other entities to exist?
Answer some (or all) the questions posed in this section.
When we talk about scents, colors, flavors and temperatures, what are we talking about? What is the common name for talking about all these kind of things? Are they things or are they something else?
Are they real? And if so, what kind of reality do they posess? Are they real in the same sense that are real plants, pigeons or planets?
Morpheus: What is real? How do you define 'real'? If you're talking about what you can feel, what you can smell, what you can taste and see, then 'real' is simply electrical signals interpreted by your brain.
The Matrix. Lana Wachowski, Lilly Wachowski
"If a tree falls in a forest and no one is around to hear it, does it make a sound?"
Philosophical riddle
Using the concepts of stimuli, sensorial receptors (senses), sensations, perceptions, etc. answer the above questions.
Also comment on the quotation from The Matrix and give an answer to the philosophical riddle.
Hint: look at the similarities between smells, colors, pains, etc. and the guiding lines that car screens show when parking.
Imagine a driver that has never abandoned its car. He only knows about the rear external world through the screen. What do you think that driver would think about those guiding lines?
Where do they seem to be?
Are those guiding lines real? Do they exist?
And when the driver eventually understand that those line are not physically real, what would be its explanation for seeing them (in the screen) and believing that they were out there?
We can define realism as the philosophical thesis that affirms that there exist realities independent of our mind, our mental processes or consciuos experiences. Its opposite thesis is called idealism: it affirms that reality is subjective, only the ideas in our minds are real, there is no external, independent world. For an idealist such as the philosopher George Berkeley (1685 - 1753) objects such as trees in a forest only exist in so far as someone (some mind) perceives them.
Realism is a very general thesis, it leaves open many questions such as:
What exactly exists independently of ourselves?
Material things? Non-material entities? Both?
Is everything that exists reducible to a single (simple) kind of thing?
How do we know the independent reality?
Using only our senses? Using only our intelligence? Using both?
Is our knowledge always dependent on our subjective or social prejudices? Or is it possible to attain objective knowledge?
Trying to answer these questions is the job of a branch of Philosophy called metaphysics and also the task of the sciences.
"Reality is exactly like it seems to us" could summarise what a naive realist believes.
So, if it seems to me that there are colors, scents, sounds, etc. out there, then they are all realities out there..
Our senses are a reliable way of knowing what is real and what is not: if I can sense something, that is real. If I can not sense something, it does not exist. Our senses are the ultimate judges of what is real and what it is not.
Naive realism is called "naive" because it is a very simple, unreflective view of reality. It does not take into account any of the considerations we have made in the above section and several others we could add, such as:
Do electrons exist? I have never seen an electron, and I never will.
Sometimes (such as when I get the flu) food does not taste the same. So, are flavors real?
We can be realists, but not of the naive kind.
"Reality is what science tells us there is" could summarise what a scientific realist believes. But this it is not very useful untill we get a clear understanding of what science is:
There is not a single science but many sciences, in plural. Each science investigates one aspect of reality. So for instance Biology deals with cells and genes, Chemistry reduces every substance to atoms and Physics tells us that atoms are made of quarks and electrons. Each science deals with different realities. Some think that all sciences will eventually converge to a single and simple reality, so reducing the currently different realities to just one. But this reductionistic approach is just one possibility and scientific realism does not require it.
We can talk of science in singular if we focus on the method that all sciences use. A key feature of this method is that knowledge is revisable through critical thinking, novel ideas and discoveries. Science is a work in progress, so our ideas about what is real are also revisable and improving. The answer to the question "what is real?" must therefore start with "according to our most recent scientific theories..."
Experimental sciences get some of their information directly from our senses, but sciences do not rely uncritically on them. Sensations must be validated by many observers and interpreted according to our best theories. Intelligence (reason) plays a central role and is the ultimate judge of what is real and what it is not.
The ancient philosopher Democritus (460-370 BC) may perhaps be considered one of the first scientific realists when he wrote:
“Nothing exists except atoms and empty space; everything else is opinion.”
With his assertion, Democritus is denying reality to our sensations, perceptions and feelings. They may only exist as manifestations or secondary realities of something more fundamental: atoms and their movements in empty space. These are the primary realities.
But his assertion lacked the fundamental caution of true scientific realism: atoms and empty space could be the basic realities according to Democritus' best knowledge. But our knowledge of physical reality has changed drastically since then: current physicists do not understand atoms as very small solid particles nor consider that space is really empty. More importantly, they consider provisional their current understanding of matter: quarks, electrons and force fields may be the ultimate constituents of physical reality, but physicists believe they are probably not.
Past scientists have believed in the reality of entities that current scientists consider inexistent: phlogiston and ether in physics, humours and miasms in medicine, fixed species and spontaneous generation in biology were all once respectable scientific concepts with believed real existence.
Can you briefly explain (some of) those old, discarded scientific concepts? What evidence did past scientists have for claiming their existence? What new concepts have replaced them? Can we affirm categorically that these new concepts have real existence?
Explain the sentence:
"Reality for the naive realist is something efortlessly and immediately given, while it is an enigma, a problem to be solved, for the scientific realist."
Languages and national borders are transient realities. Marks on paper have meaning only because we use them for transmitting information. Lines on maps are borders only because national authorities say so.
Their existence depend on social practices and conventions. They exist as long as societies use and enforce them.
Can you give examples of extinct languages and deleted borders?
Do prices exist? Are price tags the same thing as prices? Do prices exist on their own or do they depend on other realities to exist?
Does money exist? The reality of currency depends on social practices and conventions. Printed pieces of paper are money as long as societies confer them value.
Is fame real? Is fame an intrinsic property of some people? Or its existence depends on something else?
Are friendship, partnership or enemity real? They exist independently or do they depend on the existence of other entities?
Are they substantial realities? If not, which other word could we user for characterizing them?
Can you answer some or maybe all the questions posed in this section?
Most social realities are relational or relative realities. The adjective "relational" here means the opposite of "absolute" or "independent". For instance, fame is relational (depends on (or results from) the relations among persons) but age is not. Look deeper into the meaning of these adjectives and try to explain how some of the social realities mentioned above are relational and not absolute.
We deal everyday with numbers, equations, geometric figures and so on. But have we ever seen a number? Are numbers real?
Plato (424 - 348 B.C.) offers us one possible answer: mathematics is the science that studies abstract objects. Not physical, material, objects that we (sometimes) perceive with our senses, but inmaterial, non-physical, abstract objects that we can only "perceive" and understand with our minds.
Connect something said in the video with the scientific realism.
Plato's story is an allegory. What is an allegory? As in all allegories, its elements symbolize something else. What do simbolize the following elements of Plato's allegory?
The prisoners and in particular the prisoner that escapes.
The cave and the world outside the cave.
The shadows inside the cave and the objects outside.
Try to further understand Plato's philosophy answering these questions:
Why only one prisoner escapes? Why not all of them?
Why he decides to go back to the cave? And why is he received with hostility?
After looking at so many different realities, Can you pick up some examples of each kind and classify them according to the following adjectives?
objective / subjective
dependent / independent
relational / absolute
material (physical) / inmaterial
perceptible / unperceptible
measurable / unmesaurable
For instance, fame is objective (e.g. we can all agree that Gandhi is famous), but Gandhi's fame is not independent or absolute, but relational (it depends on our recognition). Fame is not a material thing nor we can perceive it with our senses. However, we can measure fame or at least compare how famous different people are: we build rankings of more and less famous people. So fame is: objective, dependent, relational, inmaterial, unperceptible and measurable.
Leaving aside what exists and focussing now on how reality changes or evolves in time, one of the most fundamental questions is:
Does the past determine the future?
Maybe not all reality is determined but only some parts of it. Therefore, it is interesting firstly to define the concept of a system as a way to talk about a fragment or a part of the whole reality.
A system is a non-empty set of entities (things that exist). Its members can be called its parts. These parts may hold causal relations among them:
A car can be described as a system whose parts maintain causal relations: e.g. the engine causes the wheels to move.
A solar system can be described as a system whose parts (the sun, planets and satellites) move according to the gravitational forces exerted by the large bodies on the small ones.
At any given time, a system has a state: the car's wheels are rotating or stopped, its headlights are on or off, etc. Planets and satellites are at certain positions and with specific velocities. Depending on our needs, states can be very detailed or just rough descriptions of systems. The description of a car made by a mechanic is probably much more detailed than what a regular driver may say about its car.
When considering causally-connected systems, it is interesting to distinguish between closed and open systems: a closed system is only affected by its member parts and by nothing else. Closed systems are isolated from the rest of the world.
Using the concepts of system and state and also the concepts of past and future, we can define determinism as follows:
A system is determinate if and only if its present state is followed by one and only one future state.
If we consider a car as a closed system, the state of its headligths one minute from now is determined by the state of its battery and the relevant switches and lamps.
If we isolate our solar system from the effects of the rest of the galaxy, Earth's position and velocity are completely determined by its position and the positions of the rest of the solar bodies.
On the contrary:
A system is indeterminate if and only if its present state is followed by one among several future states.
Determinism as a global, most general thesis about reality says that every closed system is determined, and the universe as a whole, complete system, is also determined.
Are all systems deterministic? At first sight is seems easy to find non-deterministic ones. Take for example a dice. When you throw it, its future state seems open to several possible states.
Or consider the time take by an driver to complete its daily commute. Let's take the whole city, its vehicules, pedestrians, traffic lights and so on as a closed system and ask ourselves: is its position in, say, half an hour, determined by the current state of the traffic?
An imperceptible change in the angle of your hand may cause a completely different result. Just a different reaction of just one driver in front of an amber light may provoke a cascade of consecuences that results in a two minutes or maybe a two hours delay in the journey of another driver.
A system whose future state is greatly affected by minuscule changes in its current state is called a chaotic system. That explains why it is very difficult to predict the result of a dice roll and why people get sometimes late to their jobs.
But now we are not interested in our knowledge of reality but in how reality behaves. Is the dice future state not determined by its current state? Is the state of the traffic one minute from now not determined by its current state? If they are not determined by the states of their parts, then what could possibly determine their future states?
No, chaotic systems, although very difficult or even impossible to predict, are deterministic systems. A very, very detailed description of their current states plus a sufficiently precise knowledge of the causal links among its elements could in principle let us predict their future.
The advance of sciences has discovered that apparently indeterminate systems are in fact determinate. Maybe in the future we will be able to accurately predict the roll of a dice, the traffic in a city or the Earth's weather. Or maybe not, and we will have to accept that all we will ever have are approximate predictions. But whatever our knowledge, that does not change the fact that these are deterministic systems: their current state determines (is followed by) a single future state.
Are there truly indeterminate systems? Systems that, whatever the accuracy of their descriptions evolve non-deterministically: their current state is followed by one among several future states.
For a long time, the general consensus was that there were not truly indeterminate systems and therefore that determinism was true. Now we know better: the behaviour of atoms and subatomic particles is indeterminate according to our current understanding of them. For example, some atoms are inestable and they disintegrate. Atomic disintegration is called radioactivity.
Atoms are fairly simple systems, some of them are composed of just a handful of protons, neutrons and electrons. Let's consider two inestable atoms of the most simpler kind: trittium. Two trittium atoms are identical in all its parts and they can be in the same state. But because they are inestable, they will disintegrate after a certain amount of time. But when? And do they disintegrate at the same time? Physicists have observed this phenomenon and have corroborated time and again that:
Disintegration is not affected by any external factor. It is an internal atomic process, but it is unpredictable not because of our ignorance but because it is intrinsically indeterminat. After lots of experiments, we are still unable to predict when an inestable atom disintegrates.
Each individual atom disintegrates at a different time: one trittium atom may disintegrate in the next minute, another may be remain intact for a year, even when nothing differentiates one from the other. Same initial state, two very different future states.
In 1935 the physicist Erwin Schrödinger devised a thought experiment for illustrating the macroscopic effects of the indeterminacy of radioactivity. The key of his experiment is that atomic disintegration is indeterminate: because of that, we can not predict if the cat is dead or alive. Only when we open the box we know.
In summary, is all reality deterministic? No. Different realities behave differently regarding their evolution in time:
Most of our everyday objects and machines are for all purposes deterministic systems. Each current state is inexorably followed by one and only one future state. And we can predict those future states accurately and for long periods of time if we know sufficiently well their present states. Think of the solar system and the calculations of the orbits of planets, satellites and comets. Think of cooking, treating an illnes or driving a car.
Some everyday systems are so complex that we rarely are able to predict their change: minuscule variations in their current states or small interactions that we don't notice produce great changes in their future states. These are chaotic systems. Although they follow deterministic laws, we are only able to make approximate predictions that are less and less accurate as time passes.
So determinism comes in two varieties:
a) Linear deterministic systems: small variations in the initial state only have small variations in their future. We can predict their evolution for long periods of time.
b) Caotic deterministic systems: small variations in the initial state provoke large changes in their future. We can't predict their evolution for long periods of time.
Finally, atomic and subatomic systems are genuinely indeterminate systems: they are very simple but their behaviour does not follow deterministic rules: there is more than one future for every present state. Therefore, we are completely unable to predict the future of single atoms or subatomic particles. But we can predict accurately the collective evolution of millions or billions of atoms: that's thermodynamics or electricity.
Consider the evolution in time of the following systems. Classify them into one of the three types of realities discussed in this section:
A kitchen owen
A flipping coin
The digestive system of a mouse
The path of a tornado
The trajectory of a billiard ball
The trajectory of a single electron
The stock market
An inestable (radioactive) atom
A person choosing between breaking or continuing a relationship
All realities seen up to this point can be characterized as natural. Naturalism is the philosophical thesis that affirms that all realities are natural realities. But, what do we mean by "natural"? There are several non-overlapping characteristics of natural entities:
Just ordinary, devoid of any "spiritual" meaning.
Repeatable, possibly controllable realities.
Can be known (completely or at least partially) by human reason. Usually that knowledge is scientific: shared and subjected to criticism and improvement.
Naturalism can be seen as a work in progress: as our scientific knowledge expands, so the realities now understood will enter the realm of nature.
There was a time when illness was considered the product of witchcraft, sin or just bad luck. But medicine has replaced those supernatural notions with scientific knowledge that makes illness something ordinary and in many cases under control.
Naturalism can be wrong: there may exist entities that belong to a supernatural realm. Entities that defy our attempts to know them rationally but that we somehow know of their existence. They may even influence us and be an important part of our lives, but they are not natural.
Mysticism or supernaturalism is the opposite of naturalism: it affirms that there are non-natural realities; not everything that exists belongs to nature.
The characteristics of supernatural entities are just the opposite of natural ones:
Having an spiritual quality or meaning.
Extraordinary, non-repeatable, unique and uncontrollable by us.
Can't be known by human reason. Religious experiences, emotions or art may be the ways to connect with supernatual entities.
Inmortal souls and deities are among the most discussed supernatural entities. Do they exist? The arguments in favour of the existence of God and the inmortality of the soul are far from convincing, but maybe this is to be expected because they are by definition beyond rational comprehension. That is the starting point of mysticism: there are realities beyond human comprehension. Nevertheless, the burden of the proof corresponds to those who defend the existence of supernatural entities.
Mysticism can be wrong: by rational or irrational means we may arrive at the conclusion that there are no supernatural entities. Or maybe we will explain them naturalistically (rationally) so no mistery remains.
What "virtual" means? Is it paradoxical to use the expression "virtual reality"? What kind of reality is a virtual one? Some examples?
How is augmented realty different from virtual reality? Do these "augmentations" exist? Are they real? Some examples?
Give an answer to the questions about augmented and virtual realities.
Extra (optional): do you think there are good reasons to maintain that there exist supernatural entities? In the hypothesis that there were not good reasons to believe in deities, souls and the afterlife, Would it be defensible to irrationally believe in them?