In this chapter, Alvin Plantinga argues that naturalism entails that our beliefs cannot affect our behavior, but natural selection only selects for beneficial behaviors. Consequently, natural selection cannot select for beneficial beliefs on naturalism, and thus the probability that human beings have evolved reliable cognitive faculties is low or inscrutable if evolution has occurred without supernatural guidance. Evolutionary naturalism, then, is "self-defeating" in the sense that if it were true, we would have no good grounds to believe that our cognitive faculties are reliable, and thus no good grounds to believe that evolutionary naturalism is true. Moreover, because our cognitive faculties are reliable, evolution actually provides evidence that naturalism is false--and thus there is a "religion/science conflict" between the quasi-religion of evolutionary naturalism and the science of evolution.
Draper criticizes Alvin Plantinga's argument that since unplanned evolution is not likely to produce trustworthy cognitive faculties, evolutionary naturalists cannot rationally believe anything--including naturalism itself. Draper contends that this argument rests on a crucial but faulty inference from the premise that the probability that our cognitive faculties are reliable given unplanned evolution is low or inscrutable. The conclusion that evolutionary naturalists cannot rationally believe in unplanned evolution does not follow from this "probability thesis." If the thesis were amended to claim that the probability of reliable cognitive faculties given unplanned evolution is low (as opposed to "low or inscrutable"), then it would follow that naturalists cannot trust their cognitive faculties; but this amended thesis is demonstrably false, and thus Plantinga's evolutionary argument against naturalism fails.
Paul Draper's critique of the evolutionary argument against naturalism (EAAN) alleges that it does not follow from the probability thesis that evolutionary naturalists cannot rationally believe in unplanned evolution, but that this conclusion does follow from the amended but demonstrably false thesis that the probability of reliable cognitive faculties given unplanned evolution is low. Though Plantinga disputes that the probability thesis does not entail this conclusion, he does not take up that argument here. Rather, he aims to show (contra Draper) that the probability of reliable cognitive faculties given unplanned evolution is indeed low, given that evolution selects only for "indicators," not full-fledged beliefs. If evolutionary naturalism is true, then both true and false belief content will yield equally adaptive behavior, and thus natural selection will not select for true belief content over false belief content; but then naturalism is indeed self-defeating in the sense that naturalists cannot trust the cognitive faculties that lead them to believe that naturalism is true.
Paul Draper argues that all else held equal, "naturalism is much more probable than theism," and therefore "theism is very probably false"; moreover, naturalism is simpler and smaller in scope than theism, and has much greater predictive power than theism with respect to evolutionary facts about suffering. In this response, Alvin Plantinga disputes that theism has larger scope than naturalism, and argues that what is really at issue for epistemic probability is not simplicity as Draper understands it (as "uniformity"), but "epistemic naturalness"--and that theism is more epistemically natural than naturalism. Moreover, if we treat theism as a hypothesis (rather than as a fact), theism might be subject to prima facie defeat by facts about suffering and misery, but nevertheless explain or predict a whole range of other data better than naturalism, such as our possession of reliable cognitive faculties, the existence of objective morality, the fine-tuning of the universe, the existence of abstract objects, and so on. But if some theists know that theism is true (in virtue of religious experiences. say), then their theism is not subject to defeat by facts about suffering even disregarding these explanatory advantages.
Alvin Plantinga does not challenge (and thus implicitly concedes) the soundness of Paul Draper's argument for the conclusion that certain facts about good and evil are strong evidence against theism. Plantinga does, however, challenge Draper's view that naturalism is more plausible than theism, which Draper needs to reach the further conclusion that, other evidence held equal, theism is very probably false. In addition, Plantinga challenges the significance of this final conclusion. In this chapter, Draper defends his views on plausibility and then argues that Plantinga's challenge to the significance of his final conclusion fails for two reasons. First, Plantinga fails to show that this further conclusion does not threaten the rationality or warrant of most theistic belief. Second, he mistakenly assumes that, in order to be significant, this conclusion must threaten the rationality or warrant of most theistic belief.