The allegory of the cave

What it tests What is the difference between living among appearances and knowing what is real, and what can education do about it?

The case

Socrates asks Glaucon to picture human beings in an underground den, chained from childhood by the legs and neck so that they can look only at the wall in front. Behind and above them a fire burns, and between the fire and the prisoners runs a low wall, “like the screen which marionette players have in front of them, over which they show the puppets”. Men carry statues and figures of animals along it, and the prisoners see only the shadows these cast. A voice echoing in the cave seems to come from the passing shadow. “To them,” Socrates says, “the truth would be literally nothing but the shadows of the images.” And they are, he adds, “like ourselves”. (Quotations here are from Benjamin Jowett’s translation.)

Release one prisoner and compel him to turn. The glare hurts, he cannot see the objects whose shadows he knew, and he takes the shadows to be truer. Dragged up the steep ascent into the sun, he is dazzled, and must grow accustomed to the light, seeing shadows first, then reflections in water, then the things themselves, then the stars by night, and last the sun. He would pity those below. Sent back, he would see badly in the dark and be laughed at, and if anyone tried to free another prisoner, “let them only catch the offender, and they would put him to death”.

Socrates explains his image himself. The prison-house is the world of sight, the fire is the sun, and the ascent is the soul’s rise into the intellectual world, where the idea of the good appears last of all and “is seen only with an effort”. The allegory follows the images of the sun and the divided line in the Republic.

What it is meant to show

Plato introduces it as a picture of education and the lack of it. On this reading education is the turning around of the soul, from shadows and visible things towards the Forms. The Form of the Good renders the objects of knowledge knowable, as the sun lets the eye see. The divided line, alongside which the cave is usually read, ranks kinds of cognition: imagination for images and shadows, belief for visible things, thought for mathematical reasoning, and understanding for the Forms themselves.

The image also makes a point about knowledge in a closed community. The prisoners honour those quickest to observe and predict the shadows. They have real expertise, within a framework none of them can see beyond.

Readings and replies

Scholars divide between epistemological and political readings. On the first, the cave concerns the grades of knowledge and their objects, though how the shadows, the objects and the outside world line up with the divided line is a matter of controversy. On the second, the cave is the city, and the allegory concerns the philosopher’s relation to the politics around him. In the twentieth century Martin Heidegger wrote on the allegory, and Hannah Arendt, who read it politically, criticised his interpretation.

The return matters for both. Socrates says the philosophers of the ideal city must be compelled to rule, and the Republic repeats the point several times. Karl Popper, in 1945, took Plato’s state to be a dystopia, and others have called its politics proto-totalitarian. The Republic’s political stance is contested, and defenders note that its philosophers despise political power and rule for the sake of the ruled, not for reward.

A sceptic has a different question. Nothing inside the cave lets the prisoners check that the shadows are shadows, and a prisoner who is told that his old world was an illusion has only the word of the one telling him. In the story he is made to see for himself, not persuaded.

Variations

The image has been reused by Francis Bacon, whose “idols of the cave” are the errors that arise from an individual’s own biases, and by many films, among them The Matrix (1999). Its philosophical relatives are the evil demon, the brain in a vat and the simulation argument, which ask how we could know that we are not in a cave of our own.

Why it still matters

I read one detail against the present. The echo is a voice without a speaker, attached by its hearers to the wrong source. The prisoners are not foolish: given what they can perceive, the shadow is the most plausible speaker, and their mistake is structural. A language model’s answer arrives in the grammar of assertion, attached to an interface, and it is tempting to treat the interface as a speaker. My argument in Can AI testify? is that nothing in the production of such answers stands to their truth as a speaker who knows stands to what she says.