Imagine you have been imprisoned all your life in a dark cave. Your hands and feet are shackled and your head restrained so that you can only look at the wall straight in front of you. Behind you is a blazing fire, and between you and the fire a walkway on which your captors carry statues and all sorts of objects. The shadows cast on the wall by these objects are the only things you and your fellow prisoners have ever seen, all you have ever thought and talked about.
Probably the best known of the many images and analogies used by the Greek philosopher Plato, the Allegory of the Cave, appears in Book 7 of Republic, the monumental work in which he investigates the form of the ideal state and its ideal ruler—the philosopher king. Plato’s justification for giving the reins of government to philosophers rests on a detailed study of truth and knowledge, and it is in this context that the Allegory of the Cave is used.
Plato’s conception of knowledge and its objects is complex and many-layered, as becomes clear as the parable of the cave continues.
Now suppose that you are released from your shackles and free to walk around the cave. Dazzled at first by the fire, you will gradually come to see the situation of the cave properly and to understand the origin of the shadows that you previously took to be real. And finally you are allowed out of the cave and into the sunlit world outside, where you see the fullness of reality illuminated by the brightest object in the skies, the Sun.
“Behold! human beings living in an underground den … Like ourselves … they see only their own shadows, or the shadows of one another, which the fire throws on the opposite wall of the cave.”
Plato, c.375 BC
Interpreting the cave The detailed interpretation of Plato’s cave has been much debated, but the broad significance is clear enough. The cave represents “the realm of becoming”—the visible world of our everyday experience, where everything is imperfect and constantly changing. The chained captives (symbolizing ordinary people) live in a world of conjecture and illusion, while the former prisoner, free to roam within the cave, attains the most accurate view of reality possible within the ever-changing world of perception and experience. By contrast, the world outside the cave represents “the realm of being”—the intelligible world of truth populated by the objects of knowledge, which are perfect, eternal and unchanging.
The theory of Forms In Plato’s view, what is known must not only be true but also perfect and unchanging. However, nothing in the empirical world (represented by life within the cave) fits this description: a tall person is short next to a tree; an apple that appears red at noon looks black at dusk; and so on. As nothing in the empirical world is an object of knowledge, Plato proposed that there must be another realm (the world outside the cave) of perfect and unchanging entities which he called “Forms” (or Ideas). So, for instance, it is by virtue of imitating or copying the Form of Justice that all particular just actions are just. As is suggested in the Allegory of the Cave, there is a hierarchy among the Forms, and overarching them all is the Form of the Good (represented by the Sun), which gives the others their ultimate meaning and even underlies their existence.
The idea with which Plato is most commonly associated today—so-called Platonic love—flows naturally from the sharp contrast made in the Allegory of the Cave between the world of the intellect and the world of the senses. The classic statement of the idea that the most perfect kind of love is expressed not physically but intellectually appears in another famous dialogue, Symposium.
The problem of universals Plato’s theory of Forms and the metaphysical basis that supports it may seem exotic and overelaborate, but the problem that it seeks to address—the so-called “problem of universals”—has been a dominant theme in philosophy, in some guise or other, ever since. In the Middle Ages the philosophical battle lines were drawn up between the realists (or Platonists) on one side, who believed that universals such as redness and tallness existed independently of particular red and tall things; and the nominalists on the other, who held that they were mere names or labels that were attached to objects to highlight particular similarities between them.
The same basic distinction, usually expressed in terms of realism and antirealism, still resonates throughout many areas of modern philosophy. So a realist position holds that there are entities “out there” in the world—physical things or ethical facts or mathematical properties—that exist independently of our knowing or experiencing them. Opposed to this kind of view, other philosophers, known as antirealists, put forward proposals in which there is a necessary and internal link or relation between what is known and our knowledge of it. The basic terms of all such debates were set up over 2000 years ago by Plato, one of the first and most thoroughgoing of all philosophical realists.
In defense of Socrates In his Allegory of the Cave Plato sets out to do more than illuminate his distinctive views on reality and our knowledge of it. This becomes clear in the final part of the story. Having ascended to the outside world and recognized the nature of ultimate truth and reality, the released prisoner is anxious to reenter the cave and disabuse his benighted former companions. But accustomed now to the bright light of the world outside, at first he stumbles in the darkness of the cave and is considered a fool by those who are still held captive. They think that his journey has ruined him; they don’t want to listen to him and may even try to kill him if he persists. In this passage Plato is alluding to the usual plight of the philosopher—ridicule and rejection—in attempting to enlighten ordinary people and to set them on the path to knowledge and wisdom. And in particular he is thinking of the fate of his teacher, Socrates (his mouthpiece in Republic as in most of his other dialogues), who refused throughout his life to temper his philosophical teachings and was finally, in 399 BC, executed by the Athenian state.
There is a clear echo of Plato’s Allegory of the Cave in the writing of C.S. Lewis, the author of the seven fantasy novels that together form The Chronicles of Narnia. At the end of the final book, The Last Battle, the children at the center of the stories witness the destruction of Narnia and enter Aslan’s land, a wonderful country that encompasses all that was best in old Narnia and the England they remember. The children finally discover that they have in fact died and passed from the “Shadowlands,” which was but a pale imitation of the everlasting and unchanging world they now inhabit. Despite the obvious Christian message here, the influence of Plato is clear—one of countless examples of the enormous (and often unexpected) impact the Greek philosopher has had on Western culture, religion and art.
the condensed idea
Earthly knowledge is but shadow
| Timeline | |
|---|---|
| c.375BC | Plato’s cave |
| AD1644 | Cogito ergo sum |
| 1690 | The veil of perception |
| 1981 | The brain in a vat |