Alvin Plantinga's free-will defense is a logical argument developed by the American analytic philosopher Alvin Plantinga and published in its final version in his 1977 book God, Freedom, and Evil.[1] Plantinga's argument is a defense against the logical problem of evil as formulated by the philosopher J. L. Mackie beginning in 1955.[2][3] Mackie's formulation of the logical problem of evil argued that three attributes ascribed to God (omniscience, omnipotence, and omnibenevolence) are logically incompatible with the existence of evil.