Evaluating Alvin Plantinga’s Evolutionary Argument Against Naturalism

In Where the Conflict Really Lies: Science, Religion, and Naturalism, Alvin Plantinga has argued that despite the assertions of the atheist and naturalist communities, science is not at odds with theism at all; that it is, in fact, naturalism that is in conflict with science. In the penultimate chapter of Conflict, Plantinga sets out his strongest argument to prove this point, utilizing naturalism’s favored argument as means to defeat naturalism; evolution. It is the goal of this paper to evaluate Plantinga’s Evolutionary Argument Against Naturalism (EAAN), and determine whether it succeeds, and what objections the naturalist can offer in defense against this powerful philosophical assault.

Summary

The EAAN holds that given what naturalism is – the view that everything has a natural/physical explanation, therefore supernatural explanations should be excluded – and given what we know about evolution, the two are in conflict. Why then, would naturalists always appeal to evolution as a support for their claims that ‘God did not create man,’ but that we evolved? Plantinga declares that there is no coherent support for such a belief, and goes on to formally argue his case. He begins with Darwin’s Doubt; do we have reason to think that our beliefs, evolved from those cognitive capacities of lower primates, are true?

P1) The probability (P) that our cognitive capacities are reliable (R) given that naturalism (N) and evolution (E) are true is low; [P(R/N&E) = low].

P2) If one accepts N&E, and believes that [P(R/N&E) = low], then one has a defeater for thinking R.

P3) If one has a defeater for thinking R, one has a defeater for any belief he has, including N&E.

P4) If one who accepts N&E thereby has a defeater for N&E, N&E is self-referentially incoherent

C) Therefore, N&E is self-referentially incoherent and cannot rationally be accepted

This argument is made even stronger by the fact that no defeater exists for the defeater of N&E, for if there was such a proposition, the original defeater would defeat it and the argument would disintegrate into circularity. (You cannot appeal to your reason to prove that your reason is not faulty.) So on the presumed insulation from rebuttal the EAAN appears quite successful.

Evaluation

 Given this rather strong initial approximation of Plantinga’s argument, there seems to be very little that the evolutionary naturalist may appeal to if he stays within the confines of the philosophical boundaries as presented. However, perhaps there are other avenues for the evolutionary naturalist to pursue. We will examine them now.

First, let us consider how Plantinga represents Darwin’s Doubt; he makes a considerable leap from justifiably questioning whether our cognitive faculties can be considered reliable to the somewhat outrageous conclusion that the probability of a positive answer to that question (given N&E) is very low. Whereas one can recognize a lack of certainty that some thing is the case, it is wholly arbitrary to begin assigning probability to the question. There is no support for this arbitrary assignment of probability, so one could say that premise one is highly suspect of being false unless some more firm criteria of measuring such probability it utilized.

Next, Plantinga rests a great deal of his argument on the suggestion by Patricia Churchland that our cognitive abilities are only geared toward success at the 4-F’s; fleeing, feeding, fighting, and fornicating. Here he seems to ignore a much larger issue at work in science. As presented, Plantinga tries to convince the reader that there is an indisputable, unanimous agreement within the scientific community; that all scientists doubt our cognitive abilities because evolution does not favor true belief, but only adaptive behavior. While it is true that adaptive behavior is critical to “fitness”, his suggestion that true belief has nothing to do with it is presumptuous at best. Scientists such as Philipp Khaitovich suggest that every part of our cognition is the result of an evolved metabolism function of glutamate in our brains that is not shared by our primate relatives. This entails that our highly evolved frontal lobe is vastly more sophisticated than the cerebellum of lesser-evolved primates. There seems to be no coincidence that our brain is more evolved, and that we are capable of advanced levels of understanding. And why couldn’t this be so? Human beings are apex predators only be means of our cognitive abilities; otherwise we would not fare so well in the animal kingdom; we are not as defensively gifted as large or very swift animals; we are not as suited for hunting as stronger, tooth-and-claw gifted predators; and we are much less adaptable to environmental changes. We could have instinctively recognized some need that our survival depended on, but not known how to achieve those ends without a progressively sophisticated cognitive repertoire. Therefore, our adaptive behavior can be a direct result of our highly evolved cognitive capabilities, and our fitness not merely confined to adapted habits employed by a large enough number of humans to persist in survival.

There is no consensus about what factors caused our adaptive behavior. For this reason, it does not seem reasonable for Plantinga to appeal to such a narrow view of evolutionary naturalism given that the views held in the scientific community are quite diverse. With these two objections, we can reasonably challenge the basis for Plantinga’s premises (especially P1), undercutting their strength (if any remains). To save his argument, Plantinga would have to prove that his interpretation of evolution is the only accepted version currently being used (or at least the agreed upon Peircian abductive result); but that is an untenable proposition, so his argument falls under dire conditions.

One potential method of reviving his rather bruised argument is to highlight the curious composition of our cognitive faculties.  He characterizes the naturalist’s position on cognitive faculties to be no more than physical properties of the nervous system, or neurophysiological (NP) properties. As such, he proposes that there is a large gap between the beliefs we have (the semantic properties), and the physical states of our NP properties. He is permitted in claiming this only if he is correct in saying that naturalists hold that beliefs are non-physical things. However, it is this author’s understanding of the naturalist point of view that semantic properties supervene on the biological properties, or are actually identical with it. This position actually possesses higher epistemological status than Plantinga’s proposal that our God-likeness is what gives us our ability to understand, for that which we can know through empirical data is superior to that which we suppose by faith (this is the Thomist Objection). So far, we have empirical data that shows that certain moods (“non-physical” things) are caused by the presence of certain NP properties in the brain that directly result in predictable moods. In other words, moods are physical states. Naturalism, then, seems more well-suited to answer the question about the source of semantic properties than Plantinga’s argument.

Plantinga takes this view on by claiming that if semantic properties (beliefs) are identical with some physical state (NP properties), then truth and falsity of the belief will lead to the same behavior, thus returning to the claim that evolution could not be the cause of our true beliefs because evolution is “only” concerned with behavior conducive to survival. This approach seems to fall rather flat; if belief A corresponds with physical state A, then there is no justification for saying that belief B corresponds to physical state A, also. The belief we have about some proposition is merely a token for the way we have perceive the world to be; it stands in relation to some truth-value that we can find out through empirical means. The brain functions of perception, memory, etc., are physical states that cause other physical states that we call “belief.” Behavior, then, seems to be reasoned, not random. Of course, should one deny any of this (as Plantinga does), then it must be the case that that person is a dualist of some sort, and believes in a partition between the mind, and the brain (as Plantinga does). So far, science has not supported the claims of dualism, and has favored the view that semantic properties supervene on biological factors.

In this paper, I have attempted to evaluate the EAAN, the objections to it, and the responses to those objections. Plantinga’s argument fails as a result of his reliance on the assumption that the science behind evolution is settled; that there is a unanimous and definitive accord in science that agrees that reliable cognitive abilities are irrelevant to adaptive behavior. This is not so. It may be the case that his argument prevails over those scientists, but the much wider scientific community is nowhere near such uniformity. The victory Dr. Plantinga claims, then, is much smaller than originally estimated.

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2 Responses to Evaluating Alvin Plantinga’s Evolutionary Argument Against Naturalism

  1. whitefrozen says:

    I think Planting’s case is stronger than you make it to be (of course, I regard naturalism as a proposition as silly as flat-earth or young-earth theories, so I’m biased). I also think the case against dualism is weaker than you suppose – IMO, the mind body problem, despite a large amount of ‘neruoscience’ (which generally turns out to be bad philosophy and idealism disguised as science *coughsamharrisscough* that gets thrown around to refute it.

  2. Kayleb says:

    I think it is amazing that humans can pick apart ideas to make new perspectives and help improve one another. As Kierkegaard analyzed work from another about evalution, he helped improve the understanding of the paper. By doing this, evolution was kindled from his mind, to anothers mind. I’m not going to pretend I knew everything K wrote. But, by me saying that, maybe I can kindle some evolution for the layman. For me, science is the conduit for all views. Its the fundation for understanding how life works. Yet I have much to lean about science, chemistry, biology, without forward thinking together in packs, there would not me much to talk about. I may be way off the topic, but these are views of my mind going to yours.

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