In the Phaedo, Socrates argues that he is not afraid of death because his body restricts and frustrates his quest for wisdom. In death alone can one become free of the body and seek wisdom free from material obstruction. To Socrates, the philosophic life and a search for wisdom is practising the preparation for death. However, the real arguments start only once. Cebes, one of Socrates’ friends points out that his argument pre-supposes the existence of a soul that carries on beyond death. This allows Socrates to state his doctrine of opposites, for immortality to the soul.

Socrates suggests that there is a general pattern to all change that deviates between two opposites, for example, bigger comes from smaller, faster from slower, cooler from warmer. There is a process going on in both directions between these two opposites. The opposite of the dead must then be the living. However, this argument fails to answer Cebes’ question. If we are to assume that which thinks (i.e. the self) is an immortal and separate entity, then it lies outside the opposites of life and death. Life and death can only be applied to the body, for it is the body that lives and dies. Further, the argument itself is invalid as the meaning of dead carries the meaning of having previously been alive, not just the meaning not alive. We don’t call plastic dead for it was never alive. The doctrine of opposites applies only to the opposition of living/non-living, while living/dead is a one directional process.