Plato's Republic is a dialogue in which Socrates investigates the nature of the city-state and what the ideal city-state should be. The philosophical inquiry in this dialogue can be seen as addressing two primary conceptions, conceptions which are linked under the heading of idealism, with one detailing Plato's epistemology and the other his political philosophy. The first is a more metaphysical consideration of the nature of life and the world and how we can know what we know, while the second is the practical application of various concepts to the state to demonstrate the relationship between the individual and his or her society in a utopian city-state such as Plato would create but which does not exist. Plato's Republic describes a society that is completely rational, based on Plato's concept of the good life and developed to create and protect that sort of life within the context of a civil state. What Plato seeks in this dialogue is a definition of the perfect life and the perfect state to promote and sustain that life. The primary subject of The Republic is justice, examined in broad terms. Several theories of justice are discussed in The Republic as different speakers offer their views of what justice might be, and indeed should be. In Book IV, justice is developed in terms of the inner state of the human soul.
Plato has Socrates discuss the soul and the nature of the soul and to examine ways in which the soul may be said to be made up of divisions or parts rather than being a unified whole. What emerges from this discussion is a concept of the soul as having a tri-partite nature, with the three parts joined together. These three parts are delineated as follows: 1) reason; 2) the emotional or spirited part; and 3) desire. The three parts are not equal, and for Socrates reason is the part that is to dominate and that should keep the other two parts under control.
The soul is also identified here as the mind, a...