The Central APA in Chicago this past weekend seemed fairly empty, although I heard from one of the organizers that registrations this year were about the same as last year. One of the more interesting sessions was in the very last time slot, and had Dennett commenting on Plantinga's "Science and Religion: Where the Conflict Really Lies". Partly what was remarkable about the session was how many people were there. The room was changed at the last minute to accommodate the additional interest, but even so, it was still standing room only. With at least 200 people packed into a small conference room, it was certainly one of the better attended APA events that I have been to.
I had to leave early to make my flight, so I only heard Plantinga's talk. Here I didn't hear much that was new. In the first half Plantinga argued that a committed theist could accept evolution because evolution per se is compatible with theism. This is mainly because the process of natural selection with random variation was said to be consistent with a divine plan which guided what we see as random. I am not sure how much this point of view depends on Plantinga's view that the warrant for theism is basic, but granting that point, I can see the coherence of his position.
The second half of the presentation argued that there is a quasi-religious "naturalism" which is in fact in tension with belief in evolution. Here Plantinga rehearsed his notorious argument that the combination of naturalism and evolution is self-defeating because it undermines the belief in the reliability of our cognitive faculties, and so provides a defeater for these beliefs.
Hearing the argument again drew my attention to one of the steps that seems very problematic. Plantinga's first premise is that P(R/N&E) is low. Here R is the belief that our cognitive faculties are reliable, N is naturalism and E is evolutionary theory. My concern is that even if this probability is low, that is irrelevant to the existence of defeaters. For a basic point about conditionalizing is that we should only conditionalize on our total evidence. Often this is captured by some kind of K meant to encapsulate all our background knowledge. So, even if P(R/N&E) is low, P(R/N&E&K) may be higher, and actually end up being high enough to avoid a defeater for R.
If we ignore total evidence, we can come up with easy defeaters for theism T. For example P(T/S) is low, where S is suffering. But of course theists are not forced to conditionalize on S, but can also include other beliefs from their store of background knowledge.
I am not an expert on the discussion of this argument, so maybe someone has made this objection before. Any comments are welcome, especially by those who saw the rest of the session!
Update: there is now an extended description of the session here.