Plantinga, the John A. O’Brien Professor Emeritus of Philosophy at the University of Notre Dame, said his atheist colleagues respected him “because I was a pretty good philosopher. But they also thought I had this screw loose.”

But his toughest nut to crack—especially as a theist—was the problem of evil: “It’s really hard to understand . . . why God would permit so much evil in the world. I don’t think there’s a good answer to that.”

Certainly no perfect answer, but Plantinga came close. Philosophers have long argued that the existence of both God and evil are logically incompatible. But Plantinta says that in a world of free creatures, God cannot determine their behavior, so even an omnipotent God might not be able to create a world where all creatures will always freely choose to do good. Those ideas were crystallized in his book, God, Freedom, and Evil (1974), widely regarded as having laid to rest the logical problem of evil against theism.

Plantinga further explains this “free-will defense” in this 4-minute video:

‘Pretty good arguments for theism’

In his September acceptance speech at the Templeton Prize ceremony, Plantinga concisely laid out his thinking over the last half a century. An abridged version of his remarks:

“I’ve argued that belief in God, and more specifically Christian belief, is not irrational. [M]any philosophers have argued that belief in God is indeed, irrational; and of course if it is irrational, we ought not to accept it. They think as follows: it would clearly be irrational to believe in God if there were not good evidence for the existence of God . . .

“Now what I’ve argued, in a nutshell, is this. First of all, that there are some pretty good arguments for theism, for the existence of God. More important, though, what I’ve argued is that if belief in God is true—if there really is such a person as God—then belief in God is not irrational.

“And if my argument is right, then a very common attitude among those who don’t believe in God is mistaken. That attitude goes like this: ‘I don’t know whether or not there really is such a person as God . . . but I do know the belief in God is irrational.’ My argument, very simply, is that if theism is true, then in all likelihood God would make his presence known to us human beings. And if this is so, then it would make sense to think of God as creating us in such a way that there is an innate tendency to believe in him, or at least to have some sort of inkling of his existence. This would have to be something that doesn’t depend on arguments.

“[But] most people don’t pay much attention to philosophers or philosophical arguments. That’s certainly a very sad fact, there it is: you’ll just have to get used to it.”

Answering your questions

Plantinga recently spent a lively hour with the British podcast Unbelievable, answering questions from listeners on such wide-ranging topics as evolution, naturalism, scripture, the ontological argument, and the state of his air conditioning unit.

Photo by Matt Cashore/University of Notre Dame