Good Can Exist Without Evil Whereas

From Summa Theologica Prima Pars, Questions 48–49, where Aquinas develops his theory of evil as a privatio boni — a privation or absence of good, rather than an independent force. Drawing on Aristotle and Augustine, Aquinas argued that evil has no positive existence of its own: it is a deficiency, a corruption of something good. The corollary is that good, being the fundamental nature of existence, can exist independently, while evil depends for its very definition on the good it deforms.