Moral

Socratic ethics insists that we will do what makes us happy if we know what that is. Often enough, however, when we (think we) know what will make us happy, we would rather do something else instead, and sometimes we do that something else. Also, Socratic ethics does not say enough about the soul to establish that justice and the other virtues bring the soul into its best condition or that we are happy when our souls are in their best condition.

In response to these concerns, Plato in the Republic (360 B.C.E.) distinguishes between the "rational," "emotional," and "appetitive" parts of the soul.

Each part is defined by desires: reason, by desires for what is best for us; emotion, by desires for honor, achievement, power, domination of others, and so on; and appetite, by desires for various kinds of physical pleasure. Plato also associates each part of the soul with goals: reason he associates with seeking after knowledge or understanding and emotion, and appetite with the various forms of emotional and physical gratification. Given these distinctions, Plato goes on to argue that our souls will be in better condition to the extent that our lives are structured and our practical activities are motivated by goals associated with reason, not goals associated with emotion and appetite.

Plato's metaphysics provides us with his account of the proper objects of understanding. According to his "theory of forms," the world that we are familiar with and the items populating it are merely "shadows" or "reflections" of a separate world of eternal and unchanging "forms," or "ideas," such as Number, Man, and Justice. By "sharing in" or "participating in" these most fundamental realities, ordinary objects are what they are and have the features they do. The desire to attain understanding of these entities should dominate our lives. Apprehending and appreciating formal reality, Plato thinks, makes us happy and makes our lives worth living.

It also makes us moral. Formal reality, Plato thinks, is so appealing—so riveting—as to cause us to lose interest altogether in emotional and physical forms of gratification. In consequence we will behave decently toward our fellows. Justice is thus the natural expression in the field of human relationships of a properly lived human life.