To appreciate his achievement, one should start by noting what Plantinga had to overcome. As Heather Templeton Dill said, announcing this year’s prize:
When Dr. Plantinga began his career in the late 1950’s, most academic philosophers deliberately rejected religiously informed philosophy. But early on, Dr. Plantinga defended a variety of arguments for the existence of God, marking the beginning of his efforts to put theistic belief back on the philosophical agenda.
Plantinga’s first important work, God and Other Minds, re-examined the classic arguments for and against God. It concluded that belief in the existence of God was rational, just as belief in other minds is. Arguments for the existence of other minds cannot be proven with certitude, yet most everyone accepts them as a given fact. Similarly, a religious believer’s personal encounter with the divine authorizes belief in a divine mind and creator—even if such a being cannot be strictly inferred from the secular world. Though these arguments sound simple, Plantinga worked them out with great intricacy and depth, and his book moved many skeptical minds toward belief.
His second major work, God, Freedom and Evil, proved even more consequential, as it dealt with the oft-heard objection that a good God is incompatible with a world filled with evil.