Summa Theologica, Part I (Prima Pars) / From the Complete American Edition

by Saint Aquinas Thomas

THE CAUSE OF EVIL
(In Three Articles)

We next inquire into the cause of evil. Concerning this there are three points of inquiry:

(1) Whether good can be the cause of evil?

(2) Whether the supreme good, God, is the cause of evil?

(3) Whether there be any supreme evil, which is the first cause of all evils? _______________________

FIRST ARTICLE [I, Q. 49, Art. 1]

Whether Good Can Be the Cause of Evil?

Objection 1: It would seem that good cannot be the cause of evil. For it is said (Matt. 7:18): "A good tree cannot bring forth evil fruit."

Obj. 2: Further, one contrary cannot be the cause of another. But evil is the contrary to good. Therefore good cannot be the cause of evil.

Obj. 3: Further, a deficient effect can proceed only from a deficient cause. But evil is a deficient effect. Therefore its cause, if it has one, is deficient. But everything deficient is an evil. Therefore the cause of evil can only be evil.