Plato was Socrates’ best student. He was everything Socrates wasn’t: Socrates was poor, ugly, and wonderful. Plato was rich, handsome, and a total jerk. Plato, though, is one of only a few stars that shine as brightly as Socrates. In fact, it is safe to say that had it not been for Plato, Socrates, and philosophy as we know it, would have been forgotten.

This is because Socrates never wrote anything down; Plato wrote things down for him. In fact, almost everything we know about Socrates comes from Plato’s writings. Plato made things complicated, though. While he started off by writing down Socrates’ ideas faithfully, Plato gradually started integrating his own philosophy—yet had Socrates still say the words. While this is bad enough, and makes it very difficult to distinguish Socrates’ ideas from Plato’s, Plato himself seems to have changed from a tolerable sort of fellow into quite a nasty bully. In Plato’s later work, then, Socrates ends up saying things that completely contradict what he said in places like The Apology.

Plato: Complete Works
This is the best book of the dialogues. Modern translations. Recommended.

In The Republic, for instance, Plato makes Socrates say that he quite likes a good dictatorship and that there is nothing like a rousing bunch of executions to get the citizens all pulling together. These are strange things for a man who was nearly killed for standing up to a dictatorship to be saying.

Still, The Republic is the 7th most important book in Western civilization. That’s a fact. It is Plato’s masterpiece. It is also quite long, so I haven’t included it here. What follows is a crude shortening of Plato’s fine book.

The Republic is a masterpiece because it presents a totally unified philosophy. Plato has a theory of knowledge that explains (and is explained by) his theory of metaphysics. Plato’s metaphysics explains his politics and his theory of ethics.

The central theme of The Republic is excellence, arete in Greek. Plato sees everything as having a purpose; when it fulfills that purpose, it is excellent. So, a horse’s purpose is running. An excellent horse runs well. A knife’s purpose is cutting, a fire’s purpose is warming, and so on. Plato wants to find out what a person’s purpose is, and in doing so, he finds out what a country’s purpose is.

I won’t spoil the suspense by telling you what he thinks, but I do want to point out the two most important parts of the book, at least from my perspective—and I have to say that, because The Republic can be anything. To teachers, it is a treatise on education, to politicians, a book on governance. It even has discussions of good cooking.

The Forms

There are four levels of reality. Everyone is familiar with the first two: images and physical things. The second two are different aspects of what Plato calls “The Forms”.

The Forms are complicated. They are the perfect essences of things; they are immutable, permanent, and the true reality, of which our reality is only a pale imitation. The Forms are a bit like heaven and a bit like math. They’re not of this world, but they resemble it.

Forgive me for using geometry so much, and take a triangle. Any drawn triangle is imperfect. Its sides are not perfectly straight, and its angles do not add up to 180º. A drawn triangle is an imperfect imitation of the Form of Triangle—or, as I like to say, triangle-ness. Everything that has a -ness has a Form: horsiness, humanness, squareness. Some -nesses are more basic than others, though—the perfect triangle has both triangle-ness and perfect-ness. The most basic Forms are the top level of reality, and they are things like, and including, Beauty, Truth, and Goodness.

The tripartite division of the soul

Plato thinks that there are three parts to the soul or psyche: the intellect, the will, and the appetites. The intellect makes decisions and issues instructions. The appetites are the part of the personality that says, “more, more; me, me; smoke, drink, screw”. The will is the bridge between. The weak-willed are pushed around by their appetites.

As far as I know, Plato’s division of the soul is the first attempt at psychology as a discipline of study. And for a first go, it’s pretty good.