Introduction
Platonic philosophy begins to appear in the middle dialogues. What are the important elements of this philosophy? The middle dialogues are dominated by the theory of the Forms. This is a theory that Plato developed from certain seldom-stated assumptions that Socrates held. Socrates' view was that the reason he and his interlocutors failed to find definitions for things was that they were stuck in case-based, specific examples. Does bravery mean fighting against a person stronger than yourself, or does it mean having the courage to back down from the fight and accept the insults of cowardice that come with that. Does it mean having the determination to turn your father in for murder, or bravely facing him about it, because he's your father? Such examples are bound to contradict themselves. Socrates felt that there was one bravery that was common to all these braveries, and is what makes them "brave." Plato sculpted this idea into his theory of Forms. The Forms are basically essences, they are that which truly defines a thing. By the time of the Republic, Plato had come around to the view that everything had Forms--not just virtues, but tangible things like beds, chairs, etc. We are surrounded by chairs, but there is a single Form of the "chair" that is common to all of them and makes them what they are.
The other thing we need to know about Platonic philosophy in the Republic (actually, this is true in all of his works) is that Plato believes wholeheartedly in an objective "human Good", and he feels it is the goal of philosophy to find that "Good". Plato's work rests on morality in many places, and this provides it with both passionate credibility and intellectual weakness. Plato rejected human sensory obser ...