Plato: “Allegory of the Cave”

Books are long and time is short. So being able to ask the right questions is the short cut you need. Here are three questions to explain Plato’s allegory of the cave.

First question: Why is Plato’s story called an ALLEGORY?

Plato can be very difficult to understand — even the popular Assassin’s Creed video game Odyssey featuring dialogue with Socrates and Pericles in Classical Athens didn’t include Plato. But this website is your secret weapon. The secret to understanding Plato lies in the form of writing he used himself, the dialogue. Dialogues use questions to illuminate ideas. Knowing the right questions will help you discuss Plato’s “Allegory of the Cave” like a seasoned philosopher.

So why is Plato’s story an allegory? Here is the simplest answer: Because our senses are allegories. We look up to see the sun in a bright blue sky. So we say: “The sky is blue.” The earth we stand on stretches out in every direction so we say: “The sun is small compared to the huge, heavy mass of this earth.”

But when the night comes the sky is not blue any longer — or on clear nights we’d see no stars. So why is the sky blue? Hmmmm….

And is the earth really so large? Well, it weighs 5,974,000,000,000,000,000,000,000 kilograms which sounds large, but in terms of physical mass the sun weighs 333,000 TIMES as much. And in terms of surface area? The sun can hold 1.3 million earths within its surface area – just like a jug with 1.3 million earth-sized marbles in it.

Unfortunately, realizing that “Our senses are lying to us!” is not helpful by itself. If our solid earth is really so tiny in comparison to the small disc of the sun, and if the sky’s blue color is nothing but a trick of the light, then where can we look to discover the truth?

To answer this question Plato relies upon his own teacher, Parmenides, one of the most influential thinkers in the Western political tradition.

The “Reality” section of Parmenides’ fragmentary poem”On Nature.”

If you thought Plato was tough, try Parmenides. So let’s cut to the TL;DR.

Parmenides TL;DR To know the truth you must distrust your senses. Why? Because your senses often mislead you into believing what is NOT. Sensed evidence to the contrary, the earth is NOT bigger than the sun and the sky actually is NOT blue.

OK, let’s say you are convinced Parmenides is right. You swear never, ever to use your senses again. But HOW do we distrust our senses? Plato’s answer is to use allegories. Because after all the one thing you can say for sure about an allegory is … that it isn’t true! If I tell you: “Ok there is this allegory in which the sun stands for truth …” then you know I am not talking about the sun, right? Plato argues that allegories point to new places for truth to exist.

The payoff? When you understand your senses as allegories, you become a more powerful thinker. Why? Because once you clear away the confusion of the senses, you can “see” another world — the world in which the sun is ACTUALLY larger than the earth and blue sky is ACTUALLY a trick of the light. This alternate kind of seeing reveals new objects to your mind’s eye. In this new world the sun is more massive than we can possibly imagine. And in this world the sky reflects sunlight, making transparent air appear blue during daytime. Plato calls it the “intelligible” world, the world available to our minds, just as the sense-world is available to our senses. Allegories such as Plato’s cave story open up the possibility of “seeing” by using your intellectual ability rather than getting stuck in a world of visible “things.”

Now of course, you might want to ask: But WHAT do we see in the intelligible world?

The intelligible world is made of objects of thought. We cannot see objects of thought with our eyes; they are not available to our senses. But I’m guessing you already know what kind of objects Plato means. Objects of thought include gravity, light-years, radiation, or evolution … a whole bunch of stuff. Even calculus.

Now without getting into theories of “hyper objects” and “quasi-objects” (both more recent attempts to fix Plato’s original philosophical sin of splitting “humans” from “nature”) we can probably agree that objects of thought are quite naturally part of our everyday lives. Quick – What time is it??? (There you go – we imagine time with our thoughts, not our senses.)

Second Question: Why is there a fire in the cave?

Plato's cave from left to right: images, prisoners, wall with puppeteers; fire; sunlight.
LEFT to RIGHT: Prisoners on LEFT must break free, see the fire, learn they’ve been tricked, and then ascend to sunlight on the RIGHT .
Attribution: User 4edges; Source Wikipedia Commons

There is a fire in the cave because thought can create false objects. Plato didn’t just deny the truth of our sense-data. He went much further. Basically, he said that once you’ve cleared your mind of fake sense data, then you can enter the world of the “truth” – if you have been trained to see it.

Begin your training with the question: When is light not light?

  1. [Left of Cave Diagram] Shadows are created by the absence of light. Physical objects have no light. Plato argues that uneducated people are captives in a world of shadows cast by things that have no meaning in themselves.
  2. [Middle of Cave Diagram] Firelight permits sight, but it is made by humans, so its light (or power to reveal truth) constantly changes. Plato sees firelight as an allegory for fake knowledge because fire is a human tool used to create false objects of thought. In his cave story, such false knowledge can be manipulated by politicians, demagogues, religious leaders, or other philosophers. Remember: jealous politicians used charges of impiety to get Plato’s own teacher Socrates executed.
  3. [Right of Cave Diagram] Only sunlight (actual “intellectual” knowledge or noesis achieved by logos or rational inquiry) reveals objects of thought as they really are.

So from left to right in this picture of Plato’s cave you get three stages in which light acts as an allegory to show untruth becoming more truthful. On the left, shadows which have no light represent false objects of thought based on appearances, unfounded beliefs, and seeming truths (doxa). In the middle, we see that the shadows fascinating the uneducated people are actually created by puppet masters such as Athenian politicians. Finally, on the right, only those trained to leave the cave can see with the sun’s light, which never changes, since objects of thought do not change. For example, the object of thought called a triangle cannot change or it is not a triangle. But you need to know geometry to see it.

For Plato, the allegorical FIRELIGHT makes an important point about human knowledge. People often realize they are wrong! A scientific principle can be proved wrong just as a personal belief can change. Mark Twain’s famous line says it well: “It ain’t what you know that gets you into trouble. It’s what you know for sure that just ain’t so.” For Plato the changing light of the fire shows us not only that false knowledge is possible, but that bad people will actually use false knowledge for their own purposes. Real knowledge must be based on truth that won’t change or it isn’t actually knowledge.

Plato’s sunlight is his allegory for the human ability to know the truth as the correct object of knowledge. Correct objects of knowledge do not change. If the statement that the earth actually weighs 5,974,000,000,000,000,000,000,000 kilograms is true then this statement has to stay the same or it isn’t really the Earth’s true weight. If it is true now, it has to be true later and at any other time. And so the progress of a person through the cave is an allegory for moving from shadows to firelight to sunlight, from appearances to false knowledge to the perception of reality.

To provide an historical example, in 1348-1350 some estimates hold that 50% of people in England were killed by the Black Death, carried by fleas on rats. Medieval people tended to believe this incomprehensible death-wave must be caused by breathing bad air – not an infected person’s bad air, but just bad air. In modern times, the Black Death is attributed to bubonic plague. Since bubonic plague isn’t transmitted by air, it’s the fleas.

But false knowledge prevailed. As the Black Death spread, some accused Jews of poisoning wells. This picture of innocent people being killed in Tournai (Belgium) because they have caused the plague shows how dangerous false reasoning can be.

And yet … recent analyses of actual wills left by the deceased suggest that 60% of those living in the actual medieval City of London died from plague in less than six months during 1348-1349. How could so many have been infected by fleas on rats? It doesn’t seem physically possible. After all, the very same organism causing bubonic plague still exists, and it is quite hard to catch. So perhaps the actual Black Death wasn’t bubonic plague at all, but one that was transmitted by air. For Plato, this is how sunlight works. Objects of thought such as the transmission of disease were not available to the victims of the plague in London. But once we have learned to “see” this object of thought (the concept of disease transmitted by different vectors) we can use rational inquiry to determine whether the Black Death was transmitted by air or blood. The tragic history of blaming Jews for poisoning wells can never lead to the truth. But it shows the danger of false truths for the humans in the cave.

This may be Plato’s most dangerous and influential argument. Why is there a fire in the cave? Using light in this extremely influential allegory Plato argues that the opinions or beliefs made by humans can never lead to true perception. Why? Because true knowledge is not made by humans. Objects of thought exist in reality. They exist outside the cave. So sunlight represents “true vision” — the unchanging perception of what is unchanging, of what is real. And reality can’t be part of a constantly changing physical world – what is true today has to be true tomorrow, and it has to be true for all tomorrows to come. Reality is only available to the intellect, only “visible” as an object of thought that does not change. Gravity, light-years, radiation, or evolution do not change. Correctly perceiving these objects of thought is perceiving the actual structure of the universe, not the mindless, unthinking things in the universe. To see the unchanging light of the truth, says Plato, you must learn to distrust your senses.

Question 3: Why are the prisoners in chains?

When the philosopher Xenocrates asked Plato if he could study with him, Plato refused because Xenocrates hadn’t studied any geometry. What is so great about geometry?

Finally, we’re getting to the chains. What do chains mean in the allegory of the cave?

Well, it seems kind of unfair that true knowledge is not made by humans. But humans have a problem. We are chained to flesh by our senses which belong to flesh.

The chains in Plato’s allegory are the senses. Senses chain you to what is false, to appearances that change. Try it now. Look up at the sun in the blue sky. The sun looks pretty small in the pretty blue sky, right? Your deceptive senses are LYING to you.

The truth can’t be sensed. The earth will always weigh far more than any person can sense: 5,974,000,000,000,000,000,000,000 kilograms. The sun will always be larger than the earth on the order of 1.3 million earths until the sun actually explodes, smothering the tiny speck of earth with all of its not-blue sky in stellar debris. This is not a truth that can ever be available to your senses. Truths are not available to our senses. Real knowledge is only possible for the mind trained to distrust the senses by using tools such as allegory to “see” objects of thought.

Can you see the truth now?

By this time you may have guessed Plato was a mathematician. Math is the correct language for objects of thought. To unchain herself from the flesh, from physical objects, the mathematician seeks another source of light. Now do you see the truth? Do you see what Plato was telling Xenocrates? Mathematical disciplines such as geometry allow us to see the world with the mind, not the senses. And if Xenocrates did not have the training to use his sight that way, then he couldn’t study philosophy. So long as he used physical light to see, Xenocrates could never leave the cave.