Plantinga’s EAAN and objections

Plantinga’s EAAN (Evolutionary argument against Naturalism) is an argument which tries to show that one cannot rationally belief both in the truth of metaphysical naturalism and the truth of evolutionary theory. The EAAN does not try and argue that naturalism is false[1], just that it cannot be rationally believed, specifically when combined with the truth of evolutionary theory.[2] In addition, the EAAN is not arguing the evolutionary theory is false or cannot rationally be believed.

Plantinga tries to present a formal argument for the conclusion that one cannot epistemically hold both the truth of naturalism and evolutionary theory. The argument is something like the following[3]:

1. If naturalism and evolutionary theory are both true, then the probability that our cognitive faculties are reliable is low or inscrutable[4] (“Inscrutability Thesis”)
2. If the probability of our cognitive faculties being reliable is low or inscrutable, then one has a defeater for their belief in the truth of the reliability of their cognitive faculties (“Reliability Defeater”)
3. If one has a defeater for truth of the reliability of their cognitive faculties, then one also has a defeater for all of their beliefs.
4. If one has a defeater for all of their beliefs, then one also has a defeater for their belief in the truth of naturalism and evolutionary theory. (“Naturalism Defeater”)
5. Conclusion: If naturalism and evolutionary theory are both true, then one has a defeater for their belief in the truth of naturalism and evolutionary theory.

Hence we can see that belief in naturalism and evolutionary theory is self-defeating, according to Plantinga’s argument. Plantinga is not arguing that we don’t have reliable cognitive faculties. The issue has to do whether we would have reliable cognitive faculties IF naturalism and evolutionary theory are both true.

Plantinga is concerned with metaphysical naturalism. At bottom, metaphysical naturalism is a thesis that denies the existence of supernatural entities. Plantinga also conjoins metaphysical naturalism with materialism about persons, because he says that most naturalists are materialists about persons. That is, persons just are their physical bodies/brains.

The first premise is the key premise. Plantinga goes on in length about why it’s true. First off, Plantinga thinks there is intuitive support for the premise, and he includes quotes from people like Darwin, Dawkins, and Churchland; they talk about how evolution is blind, that evolution is only concerned with survival (the four “Fs”), and that it is hard to see how we can trust our minds since they have been formed from the minds of lower animals.[5] Upon reflection, one might just see that it is true that there is an epistemic problem with holding both the truth of naturalism and evolution.

Plantinga then goes on to argue that evolution is not concerned about the issue of true beliefs. Rather, evolution is all about survival. And one can survive without having true beliefs. Given that one can survive with false beliefs, even pure instincts (i.e. no beliefs), this lends further support to Plantinga’s first premise.[6] Plantinga then invokes the principle indifference with regards to any said belief about reality (on N&E), given that one doesn’t have to have true beliefs in order to survive. So, whether, each belief is true has a probability of .50. Now if we multiply .50 times all of my independent beliefs (say, 1000 beliefs), then the probability that most of my beliefs are true is quite low (on N&E).[7] And if most of my beliefs are not true, then one can hardly say that I have reliable cognitive faculties. Having reliable cognitive faculties means that most of my beliefs needs to be true, perhaps a number around 66%-75%. This is made more plausible when Plantinga argues that semantic epiphenomenalism would plausibly be true if naturalism is true, because if naturalism is true, then materialism about persons is likely true.[8] And if materialism about persons is true, then semantic epiphenomenalism (SE) is true. SE means that the content of beliefs has no causal role, even if beliefs can have a causal role (non-epiphenomenalism).  And since SE is probably true (on naturalism), evolution can’t select belief content, including selecting true beliefs.

However, even if we grant premise 1, what follows? This is my main issue with the argument. I might say that the probability that our cognitive faculties being reliable is indeed low if both naturalism and evolutionary theory are true. But that wouldn’t entail that the probability of our cognitive faculties being reliable is low all things considered.[9] Perhaps there is another proposition, when added to evolutionary theory and naturalism, which would serve to show that the probability of our cognitive faculties being reliable is not low. Or, at least, I don’t think Plantinga has shown that the probability our cognitive faculties being unreliable is low, all things considered. For example, Stephen Law has argued that “conceptual constraints” could be the missing link. If there are conceptual constraints, then the probability of our cognitive faculties being unreliable is not low; indeed, it highly likely that our cognitive faculties would be reliable, given naturalism.  (and, thus, one can still believe in both the truth of naturalism and evolution.)[10]

I won’t say much about Plantinga’s other premises because I don’t really disagree with them, and I don’t find them implausible.[11] Take premise two. Some might argue that, in general, one can’t go from low probability to defeat.[12] But, it’s clear that in this case we can since what is being examined is our cognitive faculties themselves, which includes all of our beliefs! Hence, I think Plantinga has met the burden of proof in explaining why his case meets the exception.

I’m not sure if one couldn’t use Plantinga’s style of argument and argue that one can’t rationally hold to belief in God and reliable cognitive faculties. Such an argument would look something like Descartes’ evil demon. One could say that God has a morally sufficient reason to give us cognitive faculties that are unreliable.[13] We are just not in a position to assess the probabilities that God does not have a reason for allowing us to have cognitive faculties that are unreliable.[14]

Moreover, I wonder whether one can be a skeptic about whether naturalism is true but also accept evolutionary theory. It seems here that one can still be a methodological naturalist.

Even though I don’t fully buy into Plantinga’s argument, I think there could still be a common sense problem behind Plantinga’s argument.[15]

[1] Although, Plantinga does believe naturalism is false.

[2] Plantinga, Alvin. “Chapter 10: The Evolutionary Argument Against Naturalism.” In Where The Conflict Really Lies, 311-15. Oxford University Press, 2011.

[3] Plantinga, Alvin. “Chapter 10: The Evolutionary Argument Against Naturalism.” In Where The Conflict Really Lies, 311-315. Oxford University Press, 2011.

[4] Inscrutable=Unknowable. It does not simply mean “not known”. If something is not capable of being known, then we don’t know it. But the reverse isn’t necessarily true.

[5] Plantinga, Alvin. “Chapter 10: The Evolutionary Argument Against Naturalism.” In Where The Conflict Really Lies, 316-324. Oxford University Press, 2011.

[6] Plantinga, Alvin. “Chapter 10: The Evolutionary Argument Against Naturalism.” In Where The Conflict Really Lies, 311-50. Oxford University Press, 2011.

[7] Plantinga, Alvin. “Chapter 10: The Evolutionary Argument Against Naturalism.” In Where The Conflict Really Lies, 325-338. Oxford University Press, 2011.

[8] Plantinga, Alvin. “Chapter 10: The Evolutionary Argument Against Naturalism.” In Where The Conflict Really Lies, 325-338. Oxford University Press, 2011.

[9] Ibid. 339-350

[10] Law, S. (2012). Naturalism, evolution and true belief. Analysis, 72, 41–48.

[11] Ibid. 339-345

[12] Plantinga, Alvin. “Chapter 10: The Evolutionary Argument Against Naturalism.” In Where The Conflict Really Lies, 311-50. Oxford University Press, 2011.

[13] Law, Stephen (2015). The Pandora’s box objection to skeptical theism. _International Journal for Philosophy of Religion_ 78 (3):285-299.

[14] Ibid.

[15] Inspired by Trent Dougherty’s work on the “Common Sense Problem of Evil”