The Problem of Reality: From Plato’s Cave to Modern Idealism
II. The Problem of Reality
II.1 Am I a Prisoner in a Cave?
II.1.1. Reality vs. Appearances
In Book VII of Plato’s masterwork The Republic, Socrates, speaking with Glaucon, tells him a fable (known as “The Allegory of the Cave”) to illustrate what it’s like to be a philosopher. This allegory illustrates the suspicion that in Plato’s view, people who devote all their attention to things in the physical world—the world we experience through our senses—are like people who spend their entire lives watching television. They deal only with images, never with the reality that lies behind those images. To come to know this reality is the work of the intellect and the ultimate task of philosophy. Gorgias, the sophist, went further: there is no reality at all, only appearances, nothing outside the cavern, everything can be and not be. This seemed a pretty probable conclusion for Plato too: if only appearances exist then nothing truly exists, skepticism and relativism are the more logical conclusions. But Plato’s philosophy tried to resist this conclusion and postulated that there’s something more in the world than meets the eye.
II.1.2. Substance in Ancient Philosophy
There’s something underneath appearances which makes things to be what they truly are. The true being of entities and concepts is its substance, not its physical embodiment, because appearances change. Therefore, if anything were just its appearance, it would stop being what it was as soon as it changed. Also, nothing can be just particular things; being a tree cannot be all actual trees, for how can the idea of a tree be identical to all the existing and conceivable trees? How can something be one and more than one simultaneously? Therefore, it is not what we perceive which is more real, but what we understand that lies beyond our perceptions: eternal concepts.
Plato called those immaterial entities underlying material things Forms or Ideas. Where does a Form like “tree” exist? Today most people would say, ‘In our minds’ or ‘It doesn’t’. But Plato thought that it did exist, and in fact it was more real than the material tree. Indeed, his whole philosophy is based on the view that there are two worlds: this world of ordinary material existence. The first world consists of material things that change, die, and disappear; Plato called it the World of Becoming. It is not unreal, but it is less real than the other world, the truly real world, which he called the World of Being. In ‘the myth of the cave,’ the cave represents the world of shadows, the World of Becoming, in which we all live. The sunlight represents the truth, the World of Being, which we can know only through reason, not through experience.
Plato’s metaphysics is then dualistic; there are two different kinds of reality: one eternal, immaterial, invisible, necessary, immutable, absolute (World of Being) and a second one temporary, material, visible, contingent, mutable, and relative (World of Becoming). Actual things are just mere copies of Ideas, so reality lies beyond appearances. For Aristotle, this everyday world of things is the real world and there is no other. And in Aristotle, the things of ultimate reality—to which he gave the very important name substances—are nothing other than particular things in the world—horses, flowers, people, rocks, and so on. All humans are made of a certain matter (flesh and bones), and to exist is to exist materially (embodied), but that which makes flesh and bones humans is a certain essence, that those materials have the form of a human (say, of “rational animals”). So, for Aristotle, that which exists, the substance, is a compound of matter and form (this is called hylomorphism, from Greek hylē, “matter” and morphē, “form”). Matter and form come to be paired with another fundamental distinction, that between potentiality and actuality.
Things of just one reality are called monistic theories as opposed to dualistic theories. To be perfectly strict, Aristotle would somehow be a pluralist instead of a monist, since he postulates the existence of five different elements (earth, wind, water, fire, and aether). Anyway, ancient Greek thinkers (no matter holders of monism, dualism, or pluralism) shared: a) some criticism of knowledge based on mere appearances (they labeled it “opinion” as opposed to justified belief) and, b) the certainty that we could have access to reality itself. Direct realism claims that the senses provide us with direct awareness of the external world. We perceive objects as they really are.
II.2 Am I Tricked by an Evil Demon?
II.2.1. Realism vs. Idealism
Plato, Aristotle, and even Gorgias still shared a notion of nature (of reality, of the world) that made them inherently realists. Maybe there was a more authentic world beyond the world of becoming, maybe the world was just appearances and we could never grab the truth, no objective knowledge would be possible. Nevertheless, reality stood still. Descartes decided to destroy all previous beliefs in his quest for knowledge.
Nevertheless, Descartes’ skepticism was merely methodical and provisional; he aimed to establish something with absolute certainty, that is, undoubted. In order to find this solid foundation for knowledge in the Metaphysical Meditations, he took doubt to the extreme with the hypothesis of the Evil Demon.
Is any belief able to resist the possibility of being overwhelmingly deceived by a tricky god? Descartes found something which resists the more radical doubt, something about which not even an evil supernatural being all-powerful could possibly fool him.
This is the famous “Cogito, ergo sum”: “I think, therefore I am.” But what am I? Clearly I am a thinking substance, that’s my only certainty, the doubt concerning the existence of everything which isn’t me remains. This philosophical position is called solipsism (from Latin sole “only” ipsum “oneself”), and it is the terrible consequence of the method of doubt: I am only certain of my existence as a thinking substance and of the existence of my thoughts (beliefs, emotions, sensations…), but I could be dreaming or fooled by the evil demon about the existence of reality outside my mind or about the existence of my body. Sure, I perceive the world and feel my body, but can I be sure that my perceptions and my feelings correspond to an external reality? How can I distinguish between my inner perception of a flower within a dream and my outward perception of a real flower? Is there something like an “outward perception”? Does an external reality, as opposed to the internal reality of my ideas, exist?
Those questions are only possible if we give up direct realism (since direct realism admits no gap between external and internal reality), and claim the modern representational theory of perception, according to which the human mind generates a representation of the objects of reality from our sense data. The subject does not receive reality, but the mental representation of that reality. The fact that our mind is just connected to representations (there’s no direct access to reality) accounts for perceptual illusions, but raises the possibility of solipsism. If an interface is needed between our cognitive capacities and the external world, that is, if our cognitive capacities cannot access completely objects themselves, then the problem of reality is not anymore how can we know something beyond appearances, but whether there’s a reality outside our mind. The two main positions within this debate are realism (also called “objectivism” or “scientific realism” to distinguish it from direct realism) and idealism.
According to the modern philosophy of mind, our “experience” is something which takes place inside our mind, that is, in a place which is conceived as the “interior,” a realm with no chairs, trees, chalks… a realm separated from the “external” world. Nevertheless, reality can be saved if we consider that our inner experiences are caused by external things. Against naive or direct realism, scientific realism claims that we do not perceive things directly but indirectly since our perceptions are just caused by them. One of the main representatives of modern realism was John Locke (1634-1704) for whom certainly part of our perceptions are a subjective construct, but at least part of the information we get through our senses belongs to reality. According to Locke, we have to make a distinction between the primary qualities of objects (solidity, extension, figure, and mobility) which our mind receives because they are part of reality and are therefore objective and the secondary qualities of objects (texture, taste, color…) which do not belong to the nature of reality but to human perception and are therefore subjective.
In opposition to realism is idealism, according to which, admitting the representational theory of mind, the existence of reality is indemonstrable from perceptions. Idealism is the philosophy that says that what is real is mind, that all else—material objects, numbers, ideas—are in the mind or in some essential sense dependent upon minds for their existence. Descartes himself was not an idealist, but he established the framework [the representational theory of mind] for most later idealists when he said, in his Meditations, that the only thing one can know directly is one’s own ideas. From that, it is a short but spectacular leap to the claim that only ideas are real.” We do not receive realities but perceptions, and perceptions can only exist inside our mind, not outside, therefore it’s impossible to conclude that there is a reality outside our own perceptions.
The main representative of the first wave of modern idealism was the Irish bishop George Berkeley (1685–1753). “Berkeley held the extreme position of subjective idealism, which, simply summarized, insisted that “to be is to be perceived” (esse est percipi). According to Berkeley, it makes no sense to believe in the existence of anything that we cannot experience [he was an empiricist]. But all that we can experience, Berkeley argues, are our own ideas. We know that a stone exists because we have ideas (experiences) about it, including the visual appearance, touch, and weight of the stone, as well as the sound it makes when we scrape it, the pain it causes when we kick it, its visible effects on other things (which are also nothing but ideas in our minds). We know that our minds exist, Berkeley argues, because ideas presuppose minds.” (TBQ) What about the rest of the things that we tend to consider real? There’s no ultimate evidence that they would be something more than perceptions within our minds. If a tree falls down and nobody hears it, did it make any noise? Are there seven stars in the Big Dipper because they are seven or because I count them?
Berkeley solved this problem through God: our finite minds require God’s infinite Mind as a presupposition. I can be certain that the blackboard facing my back has not disappeared while I’m not watching it anymore because God is watching everything all the time, everything exists constantly in God’s mind (if being is being perceived, God makes everything exist since he perceives everything eternally). Descartes did something similar: the problem is that a tricky god might exist, let’s prove then that an almighty and good-willing god exists, so we can put an end to our radical doubt. But if we’re not ready to accept Berkeley’s presupposition or Descartes’ proof of the existence of God (we will discuss that in Unit VI) then what?
II.2.2. Substance in Modern Philosophy
Some philosophers defended monism (as Thales, Parmenides, and most of the pre-Socratic philosophers), others dualism (as Plato), and others pluralism (as Aristotle or Democritus).” Baruch Spinoza (1632-1677) saw that Descartes, having defined mind and body as separate substances, could not explain how they interact. Very well then, he said, I will not treat them as separate substances but as different aspects—or what he called attributes—of one and the same substance. If God is a substance separate from the substance of which mind and body are attributes, then God cannot interact with the world, which is nonsense. Therefore, Spinoza concluded, God must be that same substance and, in fact, ‘God’ is just another name for that substance. A philosopher such as Spinoza and many of the pre-Socratics, who believes in one substance, is a monist.”
Gottfried Wilhelm von Leibniz, on the other hand, agreed with Descartes that there is a plurality of substances. But Leibniz also agreed with Spinoza that substances cannot interact. Therefore, Leibniz postulated a world in which there are many substances, all of them created by God. These substances are all immaterial, and Leibniz called them monads. (God is the supermonad.) But monads do not interact. Each monad is something like an individual mind. There are no physical substances as such, only appearances.