What is evil and where does it come from? Augustine is much concerned with the problem of origin of evil. Manicheism teaches that there are two principles, good and evil, from the beginning. This world is the fighting place of these two principles. Good principle makes a man do good and evil principle does the opposite. Man does good or evil by compulsion of these principles, so cannot expect to establish his personality through his actions by free choice of his will.
Afterwards he reads some books of Neo-Platonism and learns that evil is not substance but privation of good. All that exists is good, and as we call defect of light a darkness, so evil is defect or privation of good, that is, non-existence. There is no evil in this world God has created. But there is one evil which is in man, that is sin or iniquity. This sin is by free choice of man’s will. We cannot find any other origin of sin except man’s free will. This is a crucial point of Manichean controversy.
In the “On Free Choice of the Will” Evodius, a partner of the dialogue, raises a serious question. Why did God give a man free will which chooses evil, that is, commits a sin? For what is a free will necessary? This leads us the most fundamental question, why a man needs to be free. Augustine replies that a man needs a free choice in order to live rightly and we cannot find other reason of sin except man’ s free will itself. Free will itself is good, and sin is a perversion of the will. A sinful will cannot choose good. Man must live rightly or well and choose good by his free choice because a good cannot be forced. Why must a man be free? He must be free to live rightly. Why does a man choose evil though all man wants to live well? Augustine says he does not know. Does he give up a problem? Freedom means that a will has the origin or cause of its movement. It is known through a consciousness of sin which is negative of freedom, as evil can be understood through negativeness of good.
