Alvin Plantinga is a philosopher and Protestant theologian from the University of Notre Dame. The bulk of his philosophical corpus has been in defense of Christianity.

Plantinga retired from Notre Dame earlier this year, so a lot of people are discussing his legacy. I’m in no position to assess his legacy, but I know that he’s a huge name and that we ought to be better acquainted with his philosophy.

Here, I will only present two of his most famous arguments: the free will defense and the evolutionary argument against naturalism.

The free will defense is a theodicy—a response to the logical problem of evil. His argument, in brief, is as follows:

A world containing creatures who are significantly free (and freely perform more good than evil actions) is more valuable, all else being equal, than a world containing no free creatures at all. Now God can create free creatures, but He can’t cause or determine them to do only what is right. For if He does so, then they aren’t significantly free after all; they do not do what is right freely. To create creatures capable of moral good, therefore, He must create creatures capable of moral evil; and He can’t give these creatures the freedom to perform evil and at the same time prevent them from doing so. As it turned out, sadly enough, some of the free creatures God created went wrong in the exercise of their freedom; this is the source of moral evil. The fact that free creatures sometimes go wrong, however, counts neither against God’s omnipotence nor against His goodness; for He could have forestalled the occurrence of moral evil only by removing the possibility of moral good.

Many philosophers think Plantinga answers the logical problem evil. There are some limitations to the argument, though. First, it doesn’t account for natural evils like earthquakes (though Plantinga argues that apparent natural evils may in fact be moral evils committed by fallen angels). And second, it doesn’t solve the evidential problem of evil—that certain kinds and amounts of evil are incompatible with god.

Another popular argument posed by Plantinga is the so-called evolutionary argument against naturalism. What it attempts to show is that evolution and metaphysical naturalism, when coupled together, are self-defeating. Naturalists hold reason in high esteem, but Plantinga contends that they shouldn’t if evolution is true. If our minds are the product of evolution, then we have little reason to trust their epistemic reliability. Evolution doesn’t care about what’s true, it only cares about what will further our survival and reproduction. Charles Darwin himself expressed this concern:

But then with me the horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey’s mind, if there are any convictions in such a mind?

On the other hand, if there exists a loving god who created us, then we can have confidence in our cognitive faculties (or so Plantinga would have us believe).

I’ve heard Dr. Kleiner, SHAFT’s resident Catholic philosopher, espouse the evolutionary argument against naturalism, but I’m not impressed by it. I may not fully understand the argument, however, so I’ll withhold my tentative criticisms for now.

I’ll end my introduction of Alvin Plantinga with this video:

In the video, an interviewer asks Plantinga why he believes in god. His response is surprisingly simple.

…I don’t think traditional arguments for God’s existence… are all that powerful… but it just seems to me that there really is such a person [as God]…

…When I look at the mountains, when I look at the treetops in my backyard, when I go to church, when I read the Bible, and on many other occasions I just find myself convinced that there really is such a person as God… It’s more like a personal experience than an argument or a philosophical proof…