When someone asks "how do you know that reality exists?" they are usually being provocative or coy - not asking a serious question. I say this because anyone can observe that with every action we take, we all demonstrate a complete trust in the physical reality of the external world. Every one of our actions is an accommodation and/or reaction to real world events. None of the several billion people on the planet conduct themselves as if the bus racing towards them on the highway is an illusion or someone else's biased view of reality that they may not necessarily subscribe to. No serious person truly doubts that we live in a real world. Even the holiest and most enlightened of gurus would step out of the way of that bus!
I remember early in my Philosophy 101 class, the professor introduced the classroom discussion topic, "how do we know this table is really there?" It inspired debate for the rest of the hour, and to date, I don't think it has been answered to everyone's satisfaction. Unfortunately, the short answer is "We don't know with absolute certainty", which is a deeply unsatisfying answer. The problem can be disposed of quickly with a few key observations, but one can also delve deeply into it. I will do both, but will start with the short version:
There is no way to distinguish an independent, external reality from the illusion of one, if we can assume that illusion is rich enough. Russell, Kant, Hume, and others (explained in more detail below) all reached this conclusion. Still, there are plenty of good reasons to believe in the reality of a table we see in front of us. The primary reasons to believe in reality over withholding belief is because the realist viewpoint so richly fullfills the "Criteria of Adequacy" (described below) and none of its competing explanations for our experiences do.The history of real vs illusory versions of reality have several forms. But they fall into two camps - the non-illusory theory is called "Realist". The theories that entail some form of unreality or illusion are "Anti-Realist". For this brief summary, I will group all Realist theories into a single Realist category. However, I will describe and distinguish between the interesting variety of Anti-Realist theories, below.
Descartes' Radical Skepticism
Rene Descartes practiced a form of "radical skepticism" (denying the reality of all external entities) via his principle of Dualism. This divided the universe into subjective thought and all other external entities. We really know only what is in our own consciousnesses, which divides us from the external world, and because of this, we can't even be sure of the external world. It is possible to doubt the reality of the external world and the objects it contains. Many people who are only superficially familiar with Descartes leave the story here, but this was only his starting point.
Descartes began his investigation by doubting everything except his own thought process, and then tried to re-establish and derive everything else from that. Despite his doubts, Descartes was convinced that our conception of reality was close to being correct. The purely Rational (i.e., deductive) process he used to arrive at this conclusion started with an ontological proof of God’s existence (which modern-day secular philosophers don't take seriously), along with a proof that God is good (also not taken seriously, except by theistic philosophers). According to Descartes, because of God’s demonstrated benevolence, we can trust the account of reality provided by our senses. God created the world, and He gave us functioning minds and reliable sense organs. He would not attempt to deceive us and would never engage in such a malicious deception. This would be incompatible with his fundamental goodness. Therefore, what we perceive really exists.
So, through a process that is not in favor anymore (ontological proofs of god), Descartes comes down on the side of the realists. He believed he proved that there was an external reality and that there was no reason for us to doubt what we were seeing really existed.
Subjective Idealism and Immaterialism
Bishop George Berkeley introduced the theory of Immaterialism in the mid 1700’s. It proposed that the material world does not exist independent of our minds; that the only reality is mind, ideas, and mental constructs. Berkeley summarized his theory with the motto "To be is to be perceived". This concept was his attempt to defend a spiritual world and prove God’s existence, against Newton’s mechanistic and materialistic science. It was his revolt against the Materialism he saw springing up around him with the astonishing advances being made in the physical sciences. The main point of Berkeley's philosophy is that there is no such thing as matter. It doesn't exist independent of our perceiving it - there are only minds, and ideas that occur in those minds. All the things we perceive are ideas; the fact that we perceive them means that we are ourselves essentially minds. For Berkeley, to argue that the table continues to exist when no one is looking at means one thing - its persistence in the absence of human observers means that God is still observing it. To me it appears to be yet another crafty, devious, and motivated technique to insert God into an explanation of reality when god is not needed. However, I don't believe that there is a completely iron-clad case against subjective idealism, but (as we will read further on), there are good reasons to reject it as an model of reality.
What is convincing or persuasive about Idealism? There are several justifications, but one of the simplest uses the formal logical structure called “affirming the antecedent” (AKA - modus ponens). Skeptics of claims about an external reality pose this argument:
- If we don't know that reality is not an illusion, then we don't know that external objects really exist
- We don't know that reality is not an illusion
- Therefore, we don't know that external objects really exist
- If P, then Q
- P is true
- Therefore, Q is true
Not only do we lack foolproof evidence against Subjective Idealism, but no evidence could possibly bear on it at all, since any evidence would necessarily come from the real world, and would immediately beg the question of real-world existence. In any case, there are no compelling reasons to disbelieve external reality, and plenty of reasons to believe it. No acceptable competing explanation has been proposed for our experiences in the world. This doesn’t constitute irrefutable proof, instead utilizing “inference to the best explanation”, meaning that among the only set of available explanations, Realism is by far the strongest. Further, Realism is also the only theory which aligns with the proposition made by Hilary Putnam - the "No Miracles Argument", which is “The positive argument for realism is that it is the only philosophy that doesn't make the success of science a miracle”. Admittedly, there is no particular law that requires that we should avoid invoking miracles in our theories of reality, but miracle-based explanations are highly ad-hoc and arbitrary. Experience has shown that ad-hoc explanations (explanations developed merely to cover the facts, and nothing more) are usually wrong. All the anti-realist, idealist explanations we will consider are highly ad-hoc and rely on a steady stream of miracles for them to be correct. This argues strongly against them.
Solipsism
Solipsism is Subjective Idealism taken to its extreme, radical, yet “logical” conclusion. Denying the existence of a material world, it also denies the existence minds other than the “agent” or person experiencing their own thoughts and existence. To the Solipsist, everything outside ourselves is an illusion - a dream, or some manufactured simulation of a reality that is not really there. Solipsism is a philosophical novelty, a intellectual parlor trick. It has no descriptive or predictive strength, but is immune from disproof. It is difficult to defeat, because it effectively poisons the well against all opposition. It makes it impossible to distinguish between actual reality and a thought that looks like reality. Because it rebuffs all counter-arguments with this trick it can never be proved or disproved, which makes any discussion of it fundamentally frustrating and pointless. This immunity from attack is its main charm, without which it would be utterly empty. Solipsism is both unverifiable and unfalsifiable. There is no scientific technique that could be successfully used to attack it. It not possible, even in principle, to subject it to any form of test by reference to empirical data because the empirical data themselves are part of the solipsistic dream. So, we could stop this chapter right here - we have already run into an insurmountable difficulty. There is no way to refute Solipsism.
However, we all intuitively feel that playing the Solipsism card is "cheating". It makes incredible claims that cannot be disproved, nor can they be proved. It hides behind the skirts of logic, jeering at efforts to disprove it, taking advantage of the technical limitations of logic. Our intuition tells us that it almost certainly isn't the "real" explanation of our experiences. We certainly don't think, feel, or act as if it is true in our daily lives (we would not step out into a busy freeway because we believe the cars to be an illusion!). But rescue is at hand - a later section of this chapter, "No reason to disbelieve", will explain why we can confidently and rationally reject facile, ad-hoc, too-convenient, miraculous explanations of this type.
Related concepts are Omphalos and “Last Thursdayism”. Omphalos means “navel” in Greek. It consists of the idea that the universe and everything in it was created with the appearance of age and history in Biblical times (such as Adam's navel, which would have served no purpose since he had no mother). "Last Thursdayism" takes that argument to the next level and asserts that everything was created like that only last Thursday (or even just five minutes ago). I say these are similar to Solipsism because they share with it an invulnerability from attack, even though they all appear to be absurdly unlikely. As Bertrand Russell described in The Analysis of Mind,
“There is no logical impossibility in the hypothesis that the world sprang into being five minutes ago, exactly as it then was, with a population that "remembered" a wholly unreal past. There is no logically necessary connection between events at different times; therefore nothing that is happening now or will happen in the future can disprove the hypothesis that the world began five minutes ago.”Solipsism and its cousins give its defenders an infinite, unhindered ability to "special plead" (invent one-off arguments) against any evidence that exists against them. They are arbitrarily ad hoc, possessing a wild card that answers all questions, intellectually dishonest, childish, naive, and deceptive.
Monism
This is a philosophical style that is thousands of years old and has been expressed in many civilizations round the world. Monism is the metaphysical and theological view that "all is one", that all reality (including God) is subsumed under the most fundamental category of being or existence. That being the case, according to Monism, there is no distinction between the table and anything else - it is all one essense. It is remarkable how often this theme has resurfaced in man's history. There is clearly something about our human experience that continues to bring us back to this concept - something in our psychology, in our perception, our neurology and cognition, or maybe in the universe itself, as its proponents would probably like to believe.
There are versions of this philosophy in all the major civilizations. In western philosophy, Thales, Anaximander, Anaximenes, Heraticlus, Parmenides and others supported various forms of Monism utilizing as their candidates for "one substance" elements such as air, fire, water, and infinity. In recent centuries, Monism has taken on form as Idealism and Solipsism (described above). Physicalism or materialism, also a form of monism, asserts that only the physical world is real, and that its mental and spiritual elements can be reduced to the physical.
A form of Monism exists within the Hindu tradition, called Advaita Vendanta. Advaita translates into English as "non dual". The single substance in Advaita is Brahman - the eternal, unchanging, infinite, immanent, and transcendent reality which is the Divine Ground of all matter, energy, time, space, being, thought, consciousness, etc. It does not recognize differences (tall/short, one/two, few/many, red/green, good/bad, this/that). If it were self-consistent (which apparently also doesn't even matter) it would not even recognize monist/dualist differences (though of course it does). In fact, ironically, there are several (i.e. more than one!!!) schools of Advaita that engage in spirited internet debates! Advaita happily glorifies the rejection of basic rules of logic - for example, Aristotle's three laws of thought (Identity, Non-Contradiction, and Excluded Middle). This makes it literally impossible to engage on anything resembling a conventional logic-based, reasonable discussion with its proponents.
According to this philosophy, consciousness, external reality, and god are of the same substance. These teachings make definite, hard, claims about the world - empirical claims. I think it would be far wiser for its adherents to limit their claims to the psychological experiences they have while immersed in their meditation exercises, rather than extend them to apply to the structure of the world, as a whole. I find it difficult to say anything less than that their cosmological claims are simply incredible. I have nothing to say one way or the other regarding their personal claims of transcendence. For all I know, they are enlightened, and if so, good for them. But they are still ignorant of how the reality outside of their minds is structured.
If there ever was a family of philosophical schools which could be described as "navel gazing", this is it. The evidence of history should put any question of resolution to rest - ain't gonna happen. The very definition of these concepts as being beyond logic and reason effectively prohibit ever resolving them in a rationale manner.
Metaphysical or Ontological Nihilism
This is a philosophical concept which claims that nothing actually exists. The external world doesn't exist, the individual having an experience of that world doesn't exist - nothing exists. Don't confuse this with moral nihilism (i.e., the lack of objective, external moral standards). This is a completely different concept.
As strange, maybe even ridiculous, as this seems, ontological nihilism is not entirely incoherent. Briefly, the exponents of Ontological Nihilism claim that it is not possible to distinguish "existence" from "non-existence" because (if nihilism is correct) there are no identifiable qualities to use in making this distinction. This, then, would make the entire concept of existence meaningless. Nihilist have an algorithm which can be followed to construct a completely empty world (which, I suppose is unique, in that there could not be two separate worlds or universes that are completely empty because they would be identical, thus the same). Imagine a world in which there are only finitely many objects. Suppose each object vanishes in sequence. Eventually you run down to three objects, two objects, one object and then no objects - now you have an empty world. Is this our world? I don't think so, because I see stuff around me... As much as I have looked into this, I can't find anyone who takes this seriously. It is discussed as an interesting philosophical cul-de-sac, but quickly discarded. I don't think we need to concern ourselves with it very much.
I have, on occasion, run into people who tell me they have a feeling of unreality - that the world seems like a TV show that is staged and meaningless, and that even they, themselves, feel empty and practically non-existent. Rather than being an accurate insight into reality, I think it is far more likely that these people are not thinking clearly. There is a psychiatric disorder called dissociate disorder (also depersonalization/derealization disorder) which is pretty well described by these symptoms. Rather than take their skepticism about existence seriously, the best solution would be to get them some appropriate medical attention.
A Pragmatic perspective
There is a practical way of looking at the table question. Instead of asking it in the way we have been posing it, instead ask, “Of what use is a real table versus an ideal table?” Formulated this way, it is less important to determine the factuality of existence than to determine its utility. Pragmatists do not require that beliefs must accurately reflect reality to be true. Instead they hold that the validity of beliefs depend on how helpful they are in action and inquiry. Simplistically, the large questions revolve around “what works?” rather than “what is true?” As the name implies, it is an eminently practical philosophy, not overly concerned with metaphysics, unless there is some useful advantage of one metaphysical position over another. As far as pragmatism is concerned, we can provisionally accept the reality of the table so long as that theory remains advantageous in helping explain other phenomena, such as why our dinner does not fall on the floor when we set the plate on the table. To a pragmatist, what it means to say, "there really is a table", is that we can be descriptively, predicatively, and explanatorily successful in our dealings with the world by taking there to be an enduring physical object with a certain mass and certain dimensions, on which we can place our food or magazines.
Probably Sean Carroll's "Poetic Naturalism" would be a good example of a useful approach to the question. He sometimes quotes poet, Muriel Rukeyser, to emphasize that although our universe may, technically, be built out of quarks and bosons and atoms and molecules, etc, it is more useful, informative, and productive to approach it from the position of "poetic naturalism", where each emergent level of reality has its own vocabulary and way of being. Rukeyser wrote:
“The universe is made of stories, not atoms”Carroll added on his own thoughts:
Our best approach to describing the universe is not a single, unified story but an interconnected series of models appropriate at different levels. Each model has a domain in which it is applicable, and the ideas that appear as essential parts of each story have every right to be thought of as “real.” Our task is to assemble an interlocking set of descriptions, based on some fundamental ideas, that fit together to form a stable planet of belief ... While there is only one world, there are many ways of talking about the world. “Ways of talking” shouldn’t be underestimated; they can otherwise be labeled “theories” or “models” or “vocabularies” or “stories,” and if a particular way of talking turns out to be sufficiently accurate and useful <within its domain of applicability>, the elements in its corresponding vocabulary deserve to be called real.Carroll's idea has some similarities to a concept found in Roger Scruton's book, "The Soul of the World". He used the term, "cognitive dualism" to describe the multi-level view of reality. He didn't really conceive of these views as hierarchical, but more of an "either-or" choice, complementary but non-compatible modes of comprehending the world. Cognitive dualism allows us to see the same world in two different ways: the way of science and the way of interpersonal understanding. The latter is concerned with the "Lebenswelt", or world of life. In this view, persons are treated as free subjects who can explain the reasons for their actions rather than as biological organisms whose actions can be explained by a chain of causality. Modern societies tend to forego the Lebenswelt in favor of the biological lens, but this is unfortunate. It causes us to view one another as objects rather than subjects. He argues that it’s only through religion and the mystical that we can reorient our attitudes toward meaning, gain a moral education, and confront the most difficult and important crises in our lives. Unlike Carroll, he leans on a religious backstop. But there is a similarity in that both of them agree that the same reality can be interpreted and comprehended in several different ways. There is no single "correct" view of reality. They are complementary and non-conflicting.Our fundamental ontology, the best way we have of talking about the world at the deepest level, is extremely sparse. In fact, at the most fundamental level (according to Carroll), the most basic ontology might just be the wave function of the universe, from which all other objects and phenomena (starting with Standard Model particles and forces) are "weakly emergent". But many concepts non-fundamental give us useful ways of describing higher-level, macroscopic reality. These deserve to be called “real”. Although they may not be fundamental, they certainly are real elements of our world. The key word is “useful.” There are certainly non-useful ways of talking about the world. A way of talking isn’t just a list of concepts; it will generally include a set of rules for using them, and relationships among them. Every scientific theory is a way of talking about the world ... The world is what exists and what happens, but we gain enormous insight by talking about it - telling its story - in different ways.
The classic “is the table really there” problem is not of any deep interest to Pragmatists, unless some compelling reason emerges to doubt its presence. If there is not tangible benefit we might experience, or difference that we could expect to see, based on the outcome of the "existence" question, the entire dispute is idle and moot. Anyone can see that the table appears to really be there, and if it continues to act that way, then let the question go. The chief interest of the Pragmatists was not in exploring the nature of Reality. Because there is no reason to doubt it, they provisionally accept it as a given, until a reason is provided to doubt it. The onus of responsibility, in their view, would be for others to disprove that it is there and to show why it would even matter one way or the other.
One prominent pragmatic, even "anti-realist", position is Instrumentalism. This is the pragmatic view that a scientific theory, or any theory, is a only meant to be useful tool for understanding the world, not necessarily describing the nature of entities being studied. Instrumentalists evaluate theories or concepts by how effectively they explain and predict phenomena, how well they align with their measurements, as opposed to how accurately they describe objective reality. Pragmatists are not generally interested in metaphysical questions about existence, so they would probably excuse themselves from this discussion.
The Vanishing of the Problem
To Wittgenstein, the question of reality, and Metaphysics as a whole, were not useful fields of investigation for philosophy. For him, the question of “is there an external world or not” is simply one that he would dismiss from the realm of philosophy. Is is not a question, but is a premise built into his very first assertions in his first important book, The Tractatus:
The world is everything that is the case.He concludes The Tractatus with a thought that encapsulates the entire book and is often repeated in other contexts, “what can be said at all can be said clearly, and what we cannot talk about we must pass over in silence”. So, after much difficult propositional calculus and highly structured statements, he advised us to stop trying to talk about things that we will never be able to decide. Some things must simply be observed in awe and admiration. The metaphysics of reality falls into that category – in his view, philosophy had nothing to say about it.
What is the case (a fact) is the existence of states of affairs.
His second major book, Philosophical Investigations took a very different approach. Tractatus was very concerned with the development of a precise philosophical language with which to discuss philosophical issues. Philosophical Investigations took an opposite approach. This was the beginning of his foray into “Ordinary Language" philosophy. Tractatus showed an isomorphism could exist between the "real" world and some ideal language. Philosophical Investigations showed that the quest for an ideal language and isomorphism is doomed, and that common spoken words would suffice. But with respect to the question of Reality, he reached a similar conclusion - stop worrying about it.
In both books, he attempted to clear the table of philosophical double-talk by dismissing the majority of philosophical questions as simple misuse of language. He saw a human tendency to become trapped in the language we use to describe our ideas to such a degree that the ideas become more important than the reality that they may or may not actually refer to. In many cases, associations of ideas in the mind that seem to have meaning, significance, and import don’t have external referents in the real world. But the strength and vividness of the false ideas are just as strong as that which would accompany coherent and meaningful ideas. Confused use of language disguises the underlying logical form, and renders most philosophical questions into perplexing nonsense and obscure linguistic puzzles. He felt that he had shown that most philosophical problems were caused by linguistic errors and general faulty use of language, that when resolved cause the original question to vanish (for example, how much energy was wasted in medieval scholastic debates exploring the various properties and abilities of angels?) When extended to the question of the existence of reality, the question itself doesn’t make sense. Simply because a question has legitimate syntactical form does not require that it actually have meaning and be capable of receiving a response. In other words, the logical form of the thoughts inspiring the question may not be isomorphic with any actual "state of affairs" in the world.
According to Hume
Part of our human condition is the belief in external reality. We conduct ourselves as if that world is really there, requiring no proof as we move about our day. David Hume took a close look at this belief. According to Hume, our natural belief is that we are actually experiencing physical reality. Several modern philosophers (Hume, Kant, Heidegger, and others) make the distinction between what we perceive and what is "really there". This is sometimes characterized as phenomena vs noumena. And even modern science shows us that, technically we are not really seeing/hearing/feeling the outside world, but instead are reacting to sensations that enter our brains through nerves. So, there are filters between us and the world which is causing the sensations. We experience internal representations of reality, rather than the reality itself. But, I guess when you think about, of course this is how it has to work. Without our nervous system, and without our conceptual framework, we could make no sense of the outside world at all.
The problem is that this separation make us less than absolutely certain that there really are physical objects that produce these sensations. We assume there are, but all we really are aware of are the sensations themselves, rather than the ultimate causes of those sensations. We believe that real objects cause nervous sensations, and that nervous sensations enter our awareness, and then we become conscious of those sensations, and we equate them to an external world. But this cause and effect chain, itself, is subject to some doubt, according to Hume. He argued thatour belief that events are causally related is the result of custom or habit acquired by experience. We have observed the regularity with which events of particular sorts occur together, we form the association of ideas that produces the habit of expecting the effect whenever we experience the cause. So, although causality makes sense to us, and in fact may literally come naturally to us, we cannot deductively prove that causal reasoning is justified. We can't rely on causal reasoning to convince us that there are external objects causing our sensations since this reasoning arises from our observation of a constant conjunction between causes and effects. If we know objects only by means of ideas, then we cannot use those ideas to establish a causal connection between the things and the objects they are supposed to represent.
So, according to Hume, our belief in the reality of an external world is irrational. Although it is utterly unjustifiable, our belief in the external world is natural and unavoidable. It is just something that humans do. We are in the habit of supposing that our ideas correspond to external entities, even though we can have no real evidence for it. Now, Hume thought that there really was an external world, but just felt compelled to note that you can't really prove it. He recommended that we fall back on a "mitigated skepticism" that readily concedes the limitations of human knowledge, but still continue to pursue our lives, our investigations, and in pushing the frontiers of knowledge forward. We should not be immobilized by the fact that much of life is uncertain, but should press on.
According to Kant
Kant was one of the philosophical giants the mid 1700's. He was a "Transcendental Idealist", believing that one's experience of things is much more concerned with how they appear to that person than how those things are in and of themselves. Even so, he steadfastly affirmed the existence of real objects behind the phenomena of perception; that is, he never accepted Subjective Idealism. Although he emphasized mental processes and ideas over that which was being perceived, his philosophy cannot be characterized as a form of Subjective Idealism.
Kant sought to show that inference from hard sense data (from the external world) to soft data (inside the mind) are warranted, and that empiricism agreed with claims to knowledge about nature. According to Kant, the mind perceives an external world full of independent objects (noumena) that are actually there and synthesizes experience (phenomena) from those perceptions. Reality, itself, is not mind-dependent, but our perceptions of it are. For this reason, we are forever separated from the actual world as it really is, and are limited to know only our perceptions of it - the phenomena we experience. Though we can never really know ultimate reality, and are limited to what our experience and perception contribute to it, we can at least know that, somehow, “things in themselves” really do exist “out there”. “Things in themselves” exist wholly outside our experience, and all we can say is that they exist.
Kant never denied the existence of things-in-themselves. He was convinced that he could demonstrate that a world independent of perception really existed. However, he believed that a perceptual and cognitive barrier prevented us from seeing these things-in-themselves, allowing us only to experience a “sensuous manifold” organized internally by the categories of sensibility. We cannot experience the "noumena" of the external world, but only the "phenomena" which our minds synthesize from the input we receive from that world. The mind does not passively receive information provided by the senses. Rather, it actively shapes and makes sense of that information. In other words, what we call “reality” is determined by transcendental (apriori) categories of human reason and forms of understanding, such as causality, unity, space, and time. Our senses react to stimuli that come from outside the mind, but we only have knowledge of how they appear to us once they have been processed by our faculties of sensibility and understanding. Kant used what he termed "transcendental arguments" to prove the existence of an external world separate from the individual. This type of reasoning follows this pattern:
- Begin with universally accepted premises about how our experiences are structured
- Show that certain external entities must exist for these experiences to occur
- Conclude that these other entities do, in fact, exist.
Kant popularized this type strained and dense reasoning, and it is still in use today. In my opinion this is a little complex and possibly too clever - it almost seems facile. It is typical of the kind of argument, though, that was being produced in the 1700's.
Direct or "Naïve" Realism
The naïve realist dispenses with the philosophical idea that reality is filtered by our senses, and that rather than being aware only of "sense data", our senses give us direct perception of the external world.
One of Direct Realism's most powerful proponents (whose position I happen to agree with) was G. E. Moore, who represented it as as "common sense realism". His affirmation of a common sense realist position, argued that our ordinary common-sense view of the world is largely correct. Direct Realists claim that our senses provide us with direct awareness of the external world. In contrast, some forms of idealism assert that no world exists apart from mind-dependent ideas. The large majority of Western philosophers over the last few hundred years (Kant, Locke, Leibniz, Spinoza, Berkeley, Bacon and Hume) subscribe to the idea that we perceive sense data, and that that sense data is caused by an external world. Direct realists, like Moore, on the other hand, believe that reality is not filtered by sense data, but that we directly experience the external world - that the sense data IS part of our direct experience of that world.
The realist view is that we perceive objects as they really are. They are composed of matter, occupy space and have properties, such as size, shape, texture, smell, taste and color, that are usually perceived correctly. Objects obey the laws of physics and retain all their properties whether or not there is anyone to observe them. This theory is founded on the following five assertions (as explained by John Searle in his article, Great Awakening:
- There exists a world of material objects.
- Some statements about these objects can be known to be true through sense-experience.
- These objects exist not only when they are being perceived but also when they are not perceived. The objects of perception are largely perception-independent.
- These objects are also able to retain properties of the types we perceive them as having, even when they are not being perceived. Their properties are perception-independent.
- By means of our senses, we perceive the world directly, and pretty much as it is. In the main, our claims to have knowledge of it are justified.
Scientific Realism
Scientific Realism, or just plain Realism is the view that the world described by science IS the real world, and that the objects of scientific knowledge exist independently of the minds that study them. This theory of reality allows that the theories of science are not perfectly true but "approximately true". They don't perfectly reflect reality, but do a fair job of it. Approximate truth, which is sometimes called verisimilitude, is indispensable to contemporary scientific realists. If we say the Earth is spherical, or the sun is 93 million miles away, these are approximations. Strictly speaking, they are false statements because they are not exactly right. Yet they are unarguably "approximately true". The models we use are not intended to be exact replicas of reality, but stylized representations that abstract away irrelevant details,
Realism takes the real world as an adequate working hypothesis – that what we see is what we get. Scientific Realists believe that when we perceive the world, we perceive what is actually there. Additionally, it promotes the idea that the objects of science that cannot be directly observed (atoms, black holes, gravity, electricity, sub atomic particles, magnetism, genes, galaxies very far from us, etc) have real existence that is just like that of objects that can be seen and directly experienced. Even though the objects of the micro-world are invisible to human senses, they are predicted by theory, detectable by our instruments, and transformable into data that can be observed. They act consistently with what one would expect from actually existent objects.
The fact that scientific explanations based on the existence of a real world have worked so well for so long, and that they can be utilized in technology and engineering so successfully is a powerful and convincing argument for realism. It would be a huge and improbable coincidence if non-real unobservable entities were able to generate the measurements we take of them, and then permit us use them to build new and surprising technological devices from them, allowing us to discover newer, even more bizarre and different unobservable entities. If they actually were not present, it would require an intricate and improbable set of miracles for this to occur. The theories produced by this worldview and practice both explain the existing state of affairs and predict future outcomes with unequaled power.
However, if a believer in one of the Anti-Realist theories is strongly committed to their worldview, they will not be easily shaken from it. John Worrall, a professor of philosophy of science at the London School of Economics wrote:
"Nothing in science is going to compel the adoption of a Realist attitude towards theories. But this leaves open the possibility that some form of Scientific Realism, while strictly speaking unnecessary, is nonetheless the most reasonable position to adopt."
Who cares about certainty, anyway?
If someone asks you to prove that reality exists, they are probably have in mind a deductive proof involving some sort of syllogism or other combination of premises and propositions, that lead to an inescapable conclusion. They wanted a rock solid proof which only deductive processes can supply - no no vague expressions of likelihood or probability. Unfortunately, there simply is no argument that goes like:
- Premise A
- Premise B
- Premise C
- Therefore reality exists
"There is an evident absurdity in pretending to demonstrate a matter of fact, or to prove it by any arguments apriori. Nothing is demonstrable, unless the contrary implies a contradiction. Nothing, that is distinctly conceivable, implies a contradiction. Whatever we conceive as existent, we can also conceive as non-existent. There is no being, therefore, whose non-existence implies a contradiction. Consequently there is no being, whose existence is demonstrable."Kant agreed with him:
"The reality of external objects does not admit of strict proof."According to both Hume and Kant, existence or non-existence of an external reality (or of individual things) cannot be proved through apriori (deductive) reasoning unless one or the other would cause a contradiction. It is not contradictory to assert we are all inside a giant simulation or dream. To assert that nothing is real is just as viable as its opposite. Basically agreeing with Descartes, Hume thought that if the mind only knows its own states, then those are all it can know. Because of this limitation, we cannot deduce the existence of any external objects at all. We can see the color and form of external objects, but not their “noumena” (the things-in-themselves).
Requiring deductive proofs, and expecting formal / propositional / deductive logic to always be applicable, puts an undue burden on deductive logic, asking it to do something for which it was not designed. For example, you can't prove deductively that chocolate is your favorite food, or that you are still employed at your job, or that a dropped ball will fall to the ground, or that the sun will rise tomorrow, or that you got out of bed this morning (you might still be dreaming!). These may all be very probable, but not 100% known to be true. Those issues, which are really very important (you don't want a dropped ball hitting you under the chin) are not settled by deductive proofs anyway. Humans do not use deduction in their everyday lives all that much. We infer things based on past experience, perceived likelihood of outcomes, elimination of unlikely scenarios (inference to the best explanation), and a learned set of habits about how to move through the world we find ourselves in.
Even more intriguing, you can't prove the deductive method actually works without enlisting the use of deduction. If someone rejects deductive logic, you can't insist that they believe it because it would be illogical for them not to. The logic that you are employing is the exact thing they doubt in the first place. So, we should not despair at our inability to deductively prove reality, to derive it from some commonly agreed upon premises. That expectation is "unrealistic", it is outrageous, it asks too much of deduction. Instead, we should again go to Hume for guidance on how to consider this. He said,
"We should apportion our belief according to the evidence".The evidence overwhelmingly favors reality, and there is no counter-evidence for it. Although we cannot have complete certainty about reality, we can say we have "reliable knowledge" that it exists. Hume’s solution to the lack of a deductive proof was to say that it was habit, experience, and custom that allowed us infer facts about the world, rather than deduce them. The obsessive, maybe neurotic, insistence on absolute certainty regarding the question of existence is not useful, and represents more of an obstinate psychological need than an actually important philosophical question.
Karl Popper explained this using the example of the rising sun - although there is no way to prove that the sun will rise every morning, we can hypothesize that it will do so. If only on a single morning it failed to rise, the theory would be disproved. Barring that, it is considered to be provisionally true. Likewise, with reality's existence, we can accept it as "probably true". If we are ever shown that this is not the case, we will just have to readjust our thinking.
Bertrand Russell's Reality
Bertrand Russell is one of many philosophers who addresses the issue of matter and the external world. He sets out to decide whether we can be sure that matter (i.e., the external world) exists or if we must admit that matter is something imagined, only as real as a dream might be said to be real. Our criteria for establishing the certainty of an external reality must be independent of that world. His goal is to establish that objects exists independent of our perception of them, that if we turn away from them, they continue to exist. Although we may doubt the physical existence of an object, such as a table, "we are not doubting the sense-data, which made us think there was a table," the immediate experiences of sensation. In this sense he is like Descartes, who had certainty only in his own thoughts.
If the table is real, then our confidence in our senses is well-placed, and we might be said to have reasonably inferred reality from its appearance. If we find that the table is not real, then the "whole outer world is a dream." One hypothesis affirms our common-sense view of reality, and the other holds that "we alone exist" and nothing we experience is real in our ordinary sense. Russell contends that it cannot be proved that we are not dreaming "alone in a desert," but also argues that there is no reason for supposing that this is the case.
It is always a logical possibility that we are deceived about the true nature of reality and that it is hidden from us. It is possible, he wrote, because
"no logical absurdity results from the hypothesis that the world consists of myself and my thoughts and feelings and sensations."However, Russell's argument is that though there may be no way to disprove this "uncomfortable" possibility, there was no reason in support of it either. What is simpler and more plausible is the hypothesis that independent physical objects exist "whose action on us causes our sensations." The advantage of this hypothesis is in its simplicity. It explains the phenomena of our lives with the least resort to invention. It is the most parsimonious, though it cannot be proved deductively. However, the inductive reasons for trusting in the reality of the outside world, and in taking a scientific approach to understanding it are strong:
"The general principles of science are believed because mankind have found innumerable instances of their truth and no instances of their falsehood. But this affords no evidence for their truth in the future, unless the inductive principle is assumed."
According to Moore
G. E. Moore was well known for his advocacy of common sense philosophy, and had little use for Kant's noumena/phenomena, nor Descartes' radical skepticism, nor Hume's "internal representations of reality". He believed that reality actually existed, and that we experienced it directly. His most famous attack on Idealism occurred in an essay entitled "A Defense of Common Sense". In it he contended that the Idealistic skeptics could not give good reasons for us to accept their arguments. The defenses that the Idealist could muster were far less plausible than the reasons that could be presented to accept the common sense claims about our knowledge of the real world. In other words:
- There are only two options being considered:
- there are no external objects or
- there are external objects and reality is real
- Exactly one of (1) or (2) is true, but not both
- The arguments for (1) are very weak, and the arguments for (2) are very strong
- Therefore, (2) should be believed over (1)
What is "Ultimate Reality"?
Kant, Hume, Husserl, Heidegegger, and many other Western philosophers argue that we can't perceive "ultimate reality", the noumena behind the phenomena, because it is filtered by our senses and our mental categories. Others, for mystical reasons, believe there is a "hidden world" behind the world of appearance. Both of them are essentially saying, "you don't really see the table for what it is". To those who say we can't experience a so-called "ultimate reality", I side with G.E. Moore. Like him, I question if this is even a meaningful concept. What is "ultimate reality" other than the "actual reality" we find ourselves in? If we can't experience it or ever know it, what indication is there that it is even a real thing? Are there hints that it is there, any clues other than subjective mystical experiences that mystics and gurus report? If not, and our only evidence is personal testimony from enlightened meditators, my reply is that their experience, as deep and meaningful as it may be, says more about their internal cognitive states than about anything in the outside world. I say we are living in "ultimate reality" - this is it. Ours is the only reality for which there is any evidence, at all. Every one of our cells is constrained to operate in the 4 dimensional space-time web which constitutes reality. In fact, we can't escape it - there is no place else to go!
Science, technology, and exploration have taken us across formerly unbridgeable boundaries of space, size, and time. Mathematics, literature, and philosophy have revealed previously hidden conceptual realities. But they were not hidden from us because they were forever and fundamentally unreachable, but just because we had not yet learned how to see them or were not even aware of them (for example, our galaxy, other galaxies, gravity, electromagnetic waves, the microscopic world, alternate geometries, imaginary numbers, etc). They are not intrinsically invisible to us, just difficult to see. Proponents of the idea of an unreachable "ultimate reality" have become enthralled by the intoxicating possibility that something lies beyond this mundane world, and is, by (their) definition, forever unreachable.
As Moore and Wittgenstein warned us, these people are confusing themselves with imprecise language. The term, "ultimate reality", has no tangible external referent, pointing to nothing at all. It is a description without a designated object. Ironically, this is one case where the Idealists are right - there is nothing behind this description. It is a combination of words that is, as Hume would put it, a self-contained "relation of ideas". It is not a "matter of fact", referring to an object or event in the external world. This cannot be over-emphasized: Simply stringing words together, and desiring the result to be a true and meaningful description of something and being able to conceive of such a thing in no way causes that thing to exist. The tantalizing allure of such a mystical, unreachable prize is no proof at all that it represents anything other than a daydream. It is an incoherent concept. As Russell described, this is an example of a meaningless "denoting phrase", such as what is referred to in "the present king of France is bald" (because, there is no king of France). I interpret such a statement as neither true nor false, though Russell found them to be false when examined through formal logic. However, I can agree that it does "fail to refer". This should remind us that we must remain vigilant to the misuse of words, because we are forever engaged in "a battle against the bewitchment of our intelligence by means of language".
Is it Rational to believe in Reality?
The answer to this question could influence our decision to either subscribe to a belief in an external reality, or to withhold belief. Most of us don't want to be irrational - we want to have "good reasons" for the beliefs we have. But what does it mean to be rational? What is rationality? Is it the same as logic? No, rational thought and behavior are not the same as purely logical thought and behavior. For example, being in love and acting on that love is not something that would emerge from application of purely logical principles, but one could easily argue that it is rational to have someone to love.
How does that work? Aristotle tells us that one of life's chief goals should be to live a "eudaimon" life, a life of fullfillment, happiness, having autonomy, of our lives having been a "good project", of living life well. Most human beings need close attachments to friends, need to be part of a committed relationship - these are important ingredients in such a well-lived life. So, if a goal is to live a good life, and having a loving partner is part of such a life, and achieving goals is rational, then love is rational! You would not reach that conclusion through the application of syllogisms or logical propositions without also taking the human experience into account - rationality involves logic, but also involves so much more.
A common definition of rationalism is a view that regards reason and evidence as the chief sources and tests of knowledge. Rationality is not a synonym for logic - it means that we should have a sound basis and firm foundation for our beliefs and actions, and that these should agree with the evidence. So, rationalism encompasses logic, experience, feeling, and practical aspects of what it means to have a productive and successful life. Rationality means making good decisions that lead to a successful life. It is rational to conduct yourself and conform your beliefs to events so that you most effectively and smoothly move through them. In that sense, it would be irrational to disbelieve in reality, and especially to act on that disbelief, because it would end in disaster, even death.
If you don't subscribe to Aristotle, perhaps Utilitarianism appeals to you. A Utilitarian would advise you to maximize your pleasure and minimize your pain (and to help others do the same). It would be irrational to do otherwise. Certainly, disbelieving in reality will cause much pain, and cause you to forgo much pleasure (as you miss real-world opportunities for such pleasure). In this context, it would be rational to assume the existence of external reality rather than deny it, because living a life in denial of what every experience tells us would cause a life of conflict, pain, disappointment, and failure. So, yes, by that definition of "rational", it is highly rational to belief in external reality, that the table it really there.
But if you insist that rationality must be interpreted as a synonym for deductive logic, then no - we have already seen that pure logic will not answer the question of existence. But luckily, that is not what most knowledgeable people mean by rationality. We have already seen that we can't prove the table in front of us is real. But, a rational belief would be that we can believe that the world is consistent with our experience until something demonstrates an inconsistency.
Conclusion - No reason to disbelieve
There are multiple explanations that would account for our experience of the table. The most obvious is that it is actually what it appears to be - a solid object made out of wood, which is made out of cells, which are built from molecules and atoms, which themselves are higher level constructs based on a quantum wave function, or a sub-atomic particles and forces - whatever the fundamental stuff turns out to be - and so on. This is "Realism", also called "Scientific Realism". But, as we have seen, other "Anti-Realist" explanations, or theories of reality, also exist. They include solipsism (AKA - "brain in a vat"), subjective idealism (only minds and mental constructs exist), other forms of monism, metaphyical nihilism (neither I, nor the world, exists), and a variety of mystical/religious explanations. We could be a dream that a god is having, or an elaborate computer simulation by a super-race. We might be seeing a table, but are not seeing it as it "really is" because the real "noumenal" table could be substantially different from the "phenomenal" table of our everyday experience. Which of these is true? It's hard to say - there is no way to prove one is right and the others are wrong.
When the same evidence (the experience of the table) is explainable by several theories, like those listed above, we say that the evidence "underdetermines the theories" - that is, the available evidence is not sufficient to allow us to choose between several competing theories that account for that evidence. For example, both the Copernican model and the Ptolemaic model both described the solar system. For a while, it looked like both had chances of being correct. The available observations underdetermined the theories competing to explain them. Additional evidence or observations would be necessary to eliminate one of the theories. Of course one of these theories (the Ptolemaic model) eventually lost out, both because of the maturation of the Copernican model, and because more and better observations were gathered, but sometimes multiple theories that account for the data can persist indefinitely. All the theories might do the job, but only one (at most) can be right because they are bound to be contradictory (please don't tell me I have to drop the "Law of Non-Contradiction"!). They all explain the evidence so far, but which is better? In the case for the reality of the table, no hard resolution is apparent. Expressed in symbolic form:
For any theory H there is always another theory G such that:
- If H & G are empirically equivalent (i.e., they both account for the observable evidence) then there is no reason to believe H and not G.
- We see that H & G are empirically equivalent.
- Therefore, there is no reason to believe H and not G.
Popper didn’t think we should believe H either, but it is easy to adapt his response to defend an inductivist approach to the underdetermination problem. Hence, it might be argued that if H has previously been predicatively successful, and G is ad-hoc in the sense of being introduced merely to accommodate the data without entailing any new predictions, then, given the past success of the overall method of believing empirically successful theories over ad-hoc ones, we have inductive grounds for thinking H, not G, is likely to be true.
Further, we are see that H (the theory that reality exists in the conventional way we experience it) has these other strengths or "criteria of adequacy", discussed elsewhere in this blog, (Criteria of Adequacy).
- Explanatory scope (or breadth)
- Explanatory power (or depth)
- Fruitfulness (the ability of a hypothesis to successfully predict novel and unexpected phenomena)
- Consistency (freedom from contradiction)
- Simplicity (not the brevity of the hypothesis, but the number of assumptions it has to make)
- Conservatism (how well the hypothesis fits with what we already know)
- Modesty (similar to Simplicity - all things being equal, logically less demanding hypotheses and hypotheses that make more modest claims are preferable to hypotheses that entail more assumptions, as are hypotheses that assume events of a familiar sort as opposed to those that assume unfamiliar events)
There is no compelling reason to disbelieve the Realist explanation of the world, but many strong reasons to believe it. The mystical/supernatural/science-fiction alternatives are concoctions of ad hoc, dogma-driven, just-so stories that attempt to insert god, or a Matrix-universe, mass hallucinations, a demonic deceiver, or a cosmic puppet-master as the source of our experiences. They construct an elaborate false stage on which the play, which we call reality, is being acted out by non-real actors.
Considering all the theories, no reasonable alternative explanation to Scientific Realism has been proposed - they are all far-fetched and contrived, and there are an infinite number of them. Anyone could construct their own variant of one of these miracle explanations. This doesn’t constitute irrefutable proof, instead we must consider the strengths and weaknesses of all the theories, and utilize “inference to the best explanation” to arrive at our choice. This clearly leads us to the decision that among the set of available explanations, Realism is by far the strongest. Scientific Realism has a remarkable track record that attests to the extremely high probability that it is the right way of viewing the world. Put another way, a powerful property in favor of Realism is the "no-miracles argument", according to which the consistency of our experience of reality would be miraculous if scientific theories, and the objects and processes that they refer to, were not at least approximately true descriptions of the world. All the other theories require a non-stop stream of unlikely miracles to keep them going.
