In his works, Plato describes the soul as simple and without parts, meaning that it cannot be split or divided into different sections, however, when referring to the soul in a body, Plato goes onto say it is complex. By this he means that there are different aspects to a person’s soul, but it is still in one part. He used a diamond to illustrate his point, as there are many faces on a diamond, but it cannot be split. The different faces, or aspects of the soul are similar to Freud’s division of the mind. The aspects are Reason, which searches for the truth and rules the soul; Spirit, this includes a number of aspects which can be trained, such as aggressiveness, being honourable and your emotions and Desire or Mercenary. This is linked with the idea of hedonism and seeking pleasures for the self, he split the desires up further into those that are necessary, those that are unnecessary and perverted desires. It is also known as mercenary because fufilling these desires will invariably cost money.
Plato gives two arguments for his soul. The argument from knowledge and the argument from opposties. The argument from knowledge suggests that learning is simply a matter of remembering what the soul has previously known from the world of the forms. He uses the example of “equals” here, pointing out that we can see things in equals around us, like two stones of equal size but we have never seen the form of equals, however this does not stop us from applying the concept of equals to different things.
The argument from opposites is that we can see everything in the physical world consists of opposites and that the opposite of living was death. For death to be a “thing” he said there must exist a soul to make something “alive”
Plato’s views on the soul are very much dependant on his theory of the forms and so the same weaknesses apply to both. Arguments such as how can one “see” the forms when seeing is a process linked with a body, how can a disembodied soul “see” anything? Some people see learning as acquiring new knowledge and so not an act of remembering. The argument of opposites can be disputed as the idea that everything has an opposite can be challenged.