Plato's cave
Prisoners chained in a cave see only shadows on a wall and take them for reality. What happens when one of them is freed and sees the sun?
- Reading time
- 4 min
- Difficulty
- Introductory
- Branch
- Knowledge
- First posed
- Plato, Republic, Book VII, c. 375 BCE
The setup
In the Republic, Plato has Socrates describe a strange scene. People have been chained since childhood in an underground cave, facing the back wall. They cannot turn their heads. Behind them burns a fire, and between the fire and the prisoners there is a low wall, along which people carry objects: figures of animals, tools, statues. The objects cast shadows on the wall the prisoners face.
The prisoners have never seen anything but these shadows. They name them, discuss them, and compete in predicting which will come next. For them, the shadows are reality.
Now one prisoner is freed. He turns and sees the fire, which hurts his eyes, and the objects that cast the shadows. He is confused: the shadows seemed more real. He is dragged up the steep path out of the cave into daylight, and is dazzled. Slowly his eyes adjust. He sees reflections, then things themselves, then the stars, and finally the sun, which he understands is the source of light and of the seasons and, in a sense, of everything he sees.
He pities the prisoners and goes back down to free them. But his eyes, now used to the light, cannot see well in the dark. The prisoners laugh at him; he is worse at the shadow games than they are. They conclude that going up ruins your eyes, and if they could, Socrates says, they would kill anyone who tried to lead them out.
“And if any one tried to loose another and lead him up to the light, let them only catch the offender, and they would put him to death.”
Plato, Republic, 517a (trans. Benjamin Jowett)
Why it matters
The allegory is among the most influential images in Western thought. It expresses Plato's theory that the physical world we perceive is a realm of shadows compared with the eternal forms, the perfect, unchanging realities that only reason can grasp, culminating in the Form of the Good, represented by the sun.
It is also a story about education, about how painful it can be to give up comfortable beliefs, and about the danger faced by those who try to show others the truth. Readers have long seen in the last lines a reference to the execution of Socrates.
Key terms
- Forms (Platonic)In Plato, perfect, unchanging and non-physical realities, such as Beauty itself or Justice itself, of which the things we perceive are imperfect copies.
- RationalismThe view that reason alone, independent of sense experience, is a major source of knowledge.
- SkepticismIn philosophy, the view that we know much less than we think, or nothing at all, or the practice of doubting claims to knowledge.
- Appearance and realityThe distinction between how things seem to us and how they really are. Much of philosophy, from Plato's cave to the brain in a vat, turns on whether and how we can cross that gap.
The positions
A theory of reality
The allegory teaches that the world of the senses is a realm of mere appearances. True reality is the realm of Forms, known only by reason.
A story about education
Whatever one makes of the Forms, the allegory is a profound account of learning as painful reorientation.
A political warning
The allegory warns that societies punish those who challenge their illusions, and argues that the enlightened have a duty to return and govern anyway.
Arguments and objections
A theory of reality
- Best argument
- Plato argued that sensible things are always changing and imperfect: no drawn circle is perfectly round, no beautiful thing is beautiful in every respect. Yet we understand perfect circularity and beauty itself. These must be grasped by the mind, not the senses. The ascent out of the cave is the soul's education, from images, to physical things, to mathematical truths, to the Forms themselves.
- Strongest objection
- Aristotle, Plato's own student, objected that positing separate Forms explains nothing: it doubles the world without clarifying how the Forms relate to things. The theory also struggles to say which things have Forms. Is there a Form of mud?
A story about education
- Best argument
- Plato says education is not putting knowledge into empty minds, like sight into blind eyes, but turning the whole soul toward the light. Learning is disorienting and often resisted. The freed prisoner first prefers the shadows. Anyone who has had a cherished belief overturned recognises the pattern.
- Strongest objection
- The image can encourage arrogance: those who think they have left the cave may dismiss others as prisoners. And it assumes there is one sunlit truth, which those who are skeptical about final answers may reject.
A political warning
- Best argument
- In context, the allegory is part of Plato's argument for philosopher-rulers. Those who have seen the Good must go back down into the cave and rule, even though they would rather stay in the light, because only they can rule wisely. The prisoners' hostility recalls Athens's execution of Socrates.
- Strongest objection
- Plato's idea that the wise should rule has troubled readers from Karl Popper onward, who saw in it the seeds of authoritarianism: who decides who has seen the sun?
Who argued what
- A theory of reality Plato, Plotinus
- A story about education Socrates, Plato
- A political warning Plato, Karl Popper (critic)
Variations
The modern cave
Screens, feeds and algorithms have been compared to the cave wall: curated images that people take for the world, with a fire behind them they rarely turn to see. Is this a fair comparison, or does it flatter us as the ones who have escaped?
The prisoner who stays
Suppose the freed prisoner were offered the choice to go back and be chained again, with his memory erased, so that he could enjoy the shadows in peace. Would that be a reasonable choice? See the experience machine.
Go deeper
The sun, the line and the cave
The allegory comes right after two other images in the Republic. In the Analogy of the Sun, the Good is to the intelligible world what the sun is to the visible world: the source of both being and understanding. In the Divided Line, reality is ranked from images, to physical things, to mathematical objects, to Forms. The cave dramatises both: each stage of the prisoner's ascent corresponds to a level of the line.
Related ideas
Further reading and sources
- EncyclopediaStanford Encyclopedia of Philosophy: search “allegory of the cave”
- WikipediaAllegory of the cave
- BookRepublic, Books VI and VII, Plato
- BookPlato: A Very Short Introduction, Julia Annas
Open questions
- Which of your beliefs might be shadows?
- Would you choose the painful truth over a comfortable illusion?
- Who has the right to drag anyone out of a cave?