Plato - Allegory of the cave - on knowledge and truth
Plato says that we are all like prisoners chained up on the floor of a cave. We are so restricted that we can only look in one direction, and there we see shadows on the wall that seem to talk and move around. We and our fellow prisoners observe, discuss, and remember what these shadows do or say. But, what happens if we happen to be released from our chains? We stand up and look around, and we see a fire burning at the back of the cave. In front of the fire is a low wall, and on the wall puppets are manipulated, which cast the shadows that are all we have ever seen. So suddenly we realize that all the things we have ever known all our lives were not the true reality at all, but just shadows [skiai -- significantly the same word that occurs at the end of the Meno, when Plato says that the statesman who can teach his virtue and make another into a statesman will be like the only true reality compared with shadows (100a)]. But there is more. There is an exit from the cave, which leads up to the surface. There we are at first blinded, but then begin to see trees, animals, etc. which in the cave were only represented by puppets. Eventually we notice that all those things exist and are knowable because of the sun. Returning to the cave, we would at first be blinded by the darkness, and our fellow prisoners would have no idea what we were doing or saying -- they would probably regard us as insane -- but we could not, of course, take them seriously for an instant.
On the good
Plato's actual argument for why we should be just suffers from a fundamental misconception. He is always recommending justice from prudential considerations, i.e. we should be just because of our own best interest, either to be happy (the main argument) or to avoid the punishment of the gods (in the Myth of Er). If there is a difference between moral and merely prudent action, however, Plato has misdirected us. Instead, morality may require actions that are not in our self-interest. This is agreed upon by Immanuel Kant, Confucius, and even the Bhagavad Gita. Thus, Confucius holds that righteouness, , is to do what is right, regardless of the consequences. That is how Kant defined the "categorical imperative," the moral command (the imperative) that is to no ulterior purpose (i.e. it is categorical).
