The Soul(s) of Plato

Plato seems to have had two different theories of the soul at different stages of his career. The theory advanced in the Phaedo is that the soul is a perfectly simple entity, not compounded of any parts. That is one of the reasons why 'Socrates' argues that it must be eternal -- only that which is a compound can fall apart!

The perfectly simple soul of the Phaedo must also be immaterial, because it knows the Forms, and the Forms are immaterial. A beautiful woman is embodied, but Beauty as such as not. And my soul can know Beauty, thus my soul is not as such embodied, though it seems to have been associated with a body for the last few years!

Anyway, this theory went through some changes by the time Plato wrote The Republic. There he says that the soul is divided into three part: the passions; the spirit; the intellect. Think of these as akin to Dorothy's three friends -- tinman; lion; scarecrow. Or think of them as the class structure of a city -- workers; soldiers; rulers. The point remains, Plato had begun by thinking of the soul as simple, yet here it is clearly a compound. So it presumably can dissolve at death after all?

You can reconcile these views to each other by saying that in The Republic Plato was using the word "soul" in a broader sense than he was using it in the earlier dialogue. What he calls the "intellect" in The Republic corresponds to what he meant by the "soul" in The Phaedo. So he can be taken as saying that only the intellect, the part of us that grasps the Forms, is simple and immortal. The other parts of our soul are, along with the body, dispensable upon death.