The medieval philosophy and theology blog Scholasticus has posted a fantastic quote from philosopher Peter Van Inwagen:

One advantage philosophers bring to theology is that they know too much about philosophy to be overly impressed by the fact that a particular philosopher has said this or that. Philosophers of the present day know what Thomas Aquinas and Professor Bultmann did not know: that no philosopher is an authority. Philosophers know that if you want to pronounce on, say, the project of natural theology, you cannot simply appeal to what Kant has established about natural theology. You cannot do this for the very good reason that Kant has established nothing about natural theology. Kant has only offered arguments, and the cogency of these arguments can be (and is daily) disputed.

That’s from Van Inwagen’s collection of essays God, Knowledge & Mystery, a real gem that I picked up several years back for a song at Half Price Books in Indianapolis, if I recall correctly.

When I was in graduate school I took a class on “postmodern concepts of God.” It was good in that I read stuff that I probably wouldn’t have read otherwise (Levinas, Marion), but I was continually irritated by the literary deconstructionist types who would appeal to Heidegger or Derrida or whoever as authorities for dismissing large swaths of the philosophical tradition. It just doesn’t work that way!

There’s a real problem at work here too. Theologians obviously want to make use of philosophical work but don’t necessarily have the time, training, or inclination to work through all the arguments and counterarguments. I’ve noticed, for instance, that Wittgenstein looms large in a lot of contemporary theology, often functioning in a similar appeal to authority kind of way (“As Wittgenstein has shown us…” etc.).

After all, argument has to stop at some point since you can’t justify every premise in your reasoning – as Aristotle has shown us! 😉 – but philosophers and others are understandably unimpressed by theology that takes controversial philosophical claims as given.