The Republic

In Book II, Socrates introduces the principle of specialization. According to Plato, political justice boils down to this guiding rule—that everyone do that to which their nature best suits them, and not meddle in any other business. Producers must produce according to their natures (e.g., the farmer farms, the carpenter builds wooden objects, the artist paints, and the doctor heals); warriors must fight; and the philosophers must rule.

In Book V, Socrates explains what distinguishes the lover of sights and sounds, the pseudo-intellectual, from the true philosopher. The lover of sights and sounds takes the sensible objects around him for the most real things, not recognizing that there is a higher level of reality in the intelligible realm. In particular, he goes around talking about beauty, billing himself as an expert on beauty, and yet he does not even realize that there is such a thing as the Form of the Beautiful, which is the cause of all sensible beauty.

After Socrates presents his notion of a philosopher-king in Book VI, Adeimantus objects by pointing out that all real-life philosophers are either vicious or useless. Socrates responds by drawing an analogy to a ship governed by violent men, ignorant of navigation. His intention is to demonstrate that a good philosopher would necessarily be considered useless under current circumstances. True knowledge is not valued in modern Athens, nor even believed possible, and so anyone who tries to live their life by pursuing and praising real knowledge (as the true philosopher must do) will be thought a useless fool.

Socrates describes the Form of the Good in Book VI, the ultimate object of knowledge. The Form of the Good is the source of all other Forms—the source of the entire intelligible realm, of intelligibility itself, and of our cognitive capacity to know. Though Socrates is not able to describe the Form of the Good explicitly, he attempts to give us a sense of it by comparing it to the sun. It is only when a man grasps the Form of the Good that he achieves the highest level of cognition, understanding. When a guardian takes this last step he is finally ready to become a philosopher-king.

In Book IX, Socrates presents a long and psychologically astute portrait of the tyrannical man. The tyrannical man is governed by lawless desires, the sort of desires that in normal people only emerge occasionally in dreams (desires for illicit sexual unions or heinous murders). Leading him down this nightmarish path, and egging him constantly on to greater excess, is the tyrannical man’s erotic lusts. Socrates deems erotic love the greatest tyrant of all, and regards it as a dangerous emotion, best avoided by good men.