Among Alvin Plantinga's many outstanding contributions is his career-long attempt to neutralize the challenge that evil presents for theism. This challenge takes both a logical and an evidential form. The former attempts to deduce an explicit contradiction from the existence of both God and evil, whereas the latter argues that the known evils of the world, if not rendering it improbable that God exists, at least lower the probability that he does. Plantinga meets the logical challenge with his famed free will defense and the evidential one based on the doctrine of theistic skepticism, according to which our epistemic limitations preclude our being able to determine whether these known evils are justified. Each of these responses will now be considered.

THE FREE WILL DEFENSE

The free will defense (hereafter FWD) attempts to show how it is possible for God to coexist with moral evil – evil that results from the improper use of free will by finite beings – by describing a possible world in which God is morally justified or exonerated for creating beings who freely go wrong. In response to the charge that the FWD does not go far enough because it leaves natural evil – evil that does not result from the improper use of free will by finite beings – unaccounted for, Plantinga claims that it is possible that all of the apparent natural evils of the world result from the mischief freely wrought by very powerful but finite nonhuman persons, such as wayward angels.