Plantinga's EAAN argues that evolutionary naturalism is self-defeating, i.e., the belief that naturalism (N) & evolution (E) is true defeats itself because E&N imply that probability that we are reliable (R) is low or inscrutable, which in turn provides a defeater to the belief that E&N are true. One of the crucial claims of Plantinga's argument, if not the most crucial claim, is that the Pr(R/E&N) is low or inscrutable. This means that if evolutionary naturalism is true then the chance that our belief forming mechanisms are reliable, i.e., produce mainly true beliefs, is very low or just can't be determined. Plantinga's argument for this claim involves the claim that evolution selects adaptive behavior. So the role of belief in the course of evolution lies in its adaptiveness, not solely in its truth-conditions. So far so good, but consider the problem of intentionality, "Brentano's problem". Brentano's problem is a possibility problem: how is it possible that there are states with intentional contents? For instance a belief that there are cats is an intentional state whose content is "there are cats." This content is true iff there exist an x such that x is a cat. Cat-facades, dogs that look like cats, tv-cats, raccoons on a dark night don't make that content true. The content "there are cats" zeroes in on a specific kind of biological organism--cats. Brentano's problem is very difficult for physicalists. Bill Lycan has a series of papers taking up this challenge again to existing physicalist accounts of intentionality (for starters, see Bill's paper "Giving Dualism Its Due" AJP, 2009). What does Brentano's problem have to do with Plantinga's EAAN? In short, Plantinga's right that evolutionary naturalism has a problem with true beliefs, but the reason this is a problem is because evolutionary naturalism has a problem with intentional content. One of Plantinga's examples is that the different beliefs "that is a tree" and "that is a witch-tree" might have the same adaptive behaviors. This is supposed to illustrate the point that false beliefs might be on par with true belief when it comes to adaptive behavior. That's right as far as it goes. But given that evolutionary naturalism can't explain intentional content, it's hard to see how it might throw up a belief that there are witch-trees, let alone throw up the belief that there are trees. I think the Brentano's problem is fundamental here. To put it contentiously: until we get a solution to Brentano's problem Plantinga's EAAN simply is too "down stream" to evaluate. A more agreeable way to put the point is this: Plantinga's right that evolutionary naturalism is self-defeating but the reason for this is that evolutionary naturalism can't answer Brentano's problem.