The Evolutionary Argument Against Naturalism

The Evolutionary Argument Against Naturalism

Omar Mirza*St Cloud State University

Abstract

Metaphysical naturalism can be taken, roughly, to be the view that there is no God, and nothingbeyond nature. Alvin Plantinga has argued that naturalism, in this sense, is self-defeating. Morespecifically, he argues that an evolutionary account of human origins gives the naturalist (but notthe theist) compelling reasons for doubting the reliability of human cognitive faculties, and thuscompelling reasons for doubting the truth of any of his beliefs, including naturalism itself. Thisargument, which has come to be known as the ‘evolutionary argument against naturalism’, hasgenerated a great deal of controversy, and a substantial literature concerning it has grown up as aresult. In this paper, I will introduce readers to this literature. I begin by explaining the argumentitself, and making clear its intuitive force. I then survey the main objections to it, such as the Per-spiration Objection, the ‘Can’t the Naturalist Just Add a Little Something?’ Objection, and theTu Quoque Objection: in the course of this survey, I pay particular attention to the most interest-ing of these, a version of the Tu Quoque Objection according to which the problem of evilresults in a form of epistemic self-defeat for the theist that is exactly analogous to the self-defeatwith which the naturalist is allegedly faced in the evolutionary argument. I go on to suggest that,despite the wide range of objections in the literature, the challenge of the evolutionary argumentagainst naturalism is still very much with us, and I conclude by describing some promising direc-tions for future research.

Much discussion in the philosophy of religion has been about whether or not theists arerational in believing as they do. It has frequently been argued that theistic belief is in someway epistemically defective, deplorable, or outside the pale of legitimate intellectualendeavor. These arguments have generally been put forward by adherents of metaphysicalnaturalism, the view that there is no God and nothing like God (henceforth, naturalism).

It is in this context that Alvin Plantinga has advanced the evolutionary argumentagainst naturalism (henceforth, EAAN): the aim of this argument is to show that, undercertain easily realized conditions, it is irrational to hold onto belief in naturalism (Plan-tinga, ‘Introduction’,12). The charge of irrationality that has been repeatedly leveled attheists is now directed at naturalists. Naturalism, says Plantinga, is self-defeating (‘Intro-duction’, 2). This self-defeat is meant to follow from the naturalist’s commitment to evo-lutionary theory, and her acceptance of a certain probability statement.1 Plantinga alsoargues that the same problem (of self-defeat) is not faced by theism (Warrant and ProperFunction, 236).2

What exactly is meant by ‘self-defeat’ here? To understand this, we need to considerthe idea of a defeater. To a first approximation, a defeater for a belief is a compellingreason to give up or doubt that belief.3 More precisely, to say that D is a defeater for B,relative to a person S at time t is to say the following: given that S believes D at time t, itis irrational for S to also believe B (Plantinga, ‘Naturalism Defeated’).

In general, defeaters can themselves be defeated when a person acquires new beliefs.These defeaters, which defeat earlier defeaters, will be called defeater-defeaters. If D is a

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defeater for B, relative to S, and S has no defeaters for D, D is said to be an undefeateddefeater for B (Plantinga, ‘Naturalism Defeated’).

We can now explain the conclusion that naturalism is self-defeating as follows: undercertain easily realized conditions, a naturalist will acquire an undefeated defeater for hisbelief in naturalism.4 Let’s look in a bit more detail at how the argument for this is sup-posed to work.

To begin with, let N stand for naturalism; let E stand for the view that human cogni-tive faculties have evolved by way of the mechanisms that are studied by contemporaryevolutionary theory; and let R stand for the claim that the beliefs produced by those cog-nitive faculties are for the most part true.5

EAAN has three stages, each of which involves defending a certain premise:

1. The objective conditional probability P(R ⁄N&E) is low or inscrutable (meaning thatwe cannot determine whether it is low or high): call this the Probability Thesis.

2. Anyone who accepts N and E and the Probability Thesis thereby has a defeater for R:this is the Defeater Thesis.6

3. Anyone who has a defeater for R has an undefeated defeater for each of his beliefs.

From the second and third premises, it follows that anyone who accepts N and E and theProbability Thesis has an undefeated defeater for each of his beliefs; this means that onewho accepts N and E and the Probability Thesis thereby has reason to doubt all hisbeliefs, and hence is committed to a kind of global skepticism about all his beliefs.7 Butone of those beliefs is, of course, naturalism itself; hence, anyone who accepts N and Eand the Probability Thesis has an undefeated defeater for his belief in naturalism.

Now, a rational and well-informed naturalist must accept E: it is, thinks Plantinga, theonly option for the naturalist when it comes to explaining the origin of our faculties, giventhe current state of our evidence (‘Introduction’, 12). Moreover, a rational naturalist whograsps the argument for the Probability Thesis will accept it too (granting, for the moment,that this argument is sound). So rational, well-informed naturalists who grasp the argumentfor the Probability Thesis will accept E and the Probability Thesis, and thereby acquire anundefeated defeater for their belief in naturalism. Hence, naturalism is self-defeating.

Let us see how these premises are defended.

1. Defense of the Probability Thesis

The Probability Thesis is a claim about the value of a particular objective conditionalprobability, namely P(R ⁄N&E).8 What, intuitively, is the significance of this probability?To see this, consider the case of a hypothetical population of creatures on a planet a lotlike earth, formed by blind, undirected evolution, and suppose that naturalism is true(Plantinga, ‘Introduction’, 5). Assuming further that they have and change beliefs, butthat we know nothing else relevant about them, how likely is it that their cognitive fac-ulties are reliable? The answer to this question is the value of P(R ⁄N&E).

Now there are two broad classes of view regarding the likely effect of evolutionary ori-gins on cognitive reliability (Warrant and Proper Function, 218–19). On the one hand,there are those who think that the fact that we have evolved and survived makes it likelythat our cognitive faculties are indeed reliable9: on this kind of view, P(R ⁄N&E) will behigh. On the other hand, there are those who think that our evolutionary history givesus grounds for doubting our cognitive reliability, or at least fails to give us any grounds

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for affirming it10: on this kind of view, P(R ⁄N&E) will be low, or at any rate, can’t rea-sonably be affirmed to be high.

So, who is right here? What is P(R ⁄N&E)? Let’s start by thinking about those hypo-thetical creatures: this will help us avoid any undue bias that could result from our priorconviction that our own cognitive faculties are reliable (Plantinga, ‘Introduction’, 5). Weare assuming that naturalism is true, and most contemporary naturalists will be materialistswith respect to humans and other conscious beings, so we will assume that these creaturesare material objects, and that their beliefs are neural states or processes.11 Note also that,so far, we have not been given that the beliefs of these hypothetical creatures are con-nected to their actions in anything like the way we take for granted. For all we knowtheir beliefs and their actions might have a common cause without in any way causingeach other, or their beliefs might cause actions by virtue of the neurophysiological prop-erties of those beliefs, but not by virtue of their content.12 A number of such possibilitiesare considered by Plantinga in different presentations of the argument, but these can bereduced to two (‘Introduction’, 10):C The contents of the beliefs of these creatures enter into the causal chains leading to

actions.�C The contents of the beliefs of these creatures do not enter into the causal chains

leadings to actions.The probability calculus now gives us the following formula:

P(R/N&E) ¼ P(R/N&E&C) P(C/N&E)þ P(R/N&E&~C)P(~C/N&E)

P(R ⁄N&E) is then evaluated by estimating each of the four terms that appear in the for-mula (Plantinga, ‘Introduction’, 10).

P(R ⁄N&E&�C) is estimated as low, because in this case the contents of beliefs will beinvisible to natural selection and so there will be no selection pressure towards those con-tents being mostly true (Plantinga, ‘Reply’, 253).

It seems, initially, as though P(R/N&E&C) is going to be very high, but Plantingacontests this estimate by arguing, on the basis of examples, that there are indefinitelymany possible belief systems with mostly false beliefs, but which nevertheless lead to felic-itous action (Plantinga, ‘Reply’, 253). Plantinga concludes that P(R ⁄N&E&C) will be atbest moderately high, not very much more than ½.

How do we estimate the probabilities P(C ⁄N&E) and P(�C ⁄N&E)? Note that �Ccorresponds to the view labeled ‘semantic epiphenomenalism’ in the philosophy of mind.Plantinga thinks that, because of the enormous difficulties that naturalists face in avoidingsemantic epiphenomenalism, P(�C ⁄N&E) should be estimated as very high, which inturn means that P(C ⁄N&E) is very low (‘Introduction’, 10).

Plantinga claims that a reasonable evaluation of the probabilities leads to an estimateof P(R ⁄N&E) as being somewhat less than ½ (‘Introduction’, 10). We can reconstructthe reasoning behind this evaluation as follows: the formula above is a weighted average ofP(R ⁄N&E&C) and P(R ⁄N&E&�C), and since P(�C ⁄N&E) is very high, P(R ⁄N&E&�C),which is very low, is weighted much more heavily than P(R ⁄N&E&C); hence, it is reason-able to think that P(R ⁄N&E) is low.13

A natural objection to this argument is that we should be agnostic about these proba-bilities, and hence we should think that P(R ⁄N&E) is inscrutable to us (Plantinga, ‘Intro-duction’, 10). Plantinga concedes that this is a reasonable stance, and says that P(R ⁄N&E)is either low, or inscrutable, specified to the hypothetical creatures. But, he thinks, the

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value of this probability will be the same for us as it is for those creatures (‘Introduc-tion’,10). And this concludes the defense of the Probability Thesis.14

2. Defense of the Defeater Thesis

The Defeater Thesis is defended by appealing to epistemic intuitions about hypotheticalcases that, it is claimed, are clearly analogous to the case of the naturalist in EAAN: since,in these cases, the subject has a defeater for R, the same is claimed to be true of the natu-ralist who accepts the Probability Thesis. One hypothetical case that has been central indiscussions of EAAN is the XX Case (Plantinga, ‘Reply’, 208).

XX Case. Suppose a man believes that he has taken an unreliability-inducing drugcalled XX. He also believes that the drug is capable of causing massive unreliability inthose who take it, so that even the most elementary and intuitively obvious cognitiveoperations are affected; he believes this unreliability to be of such an extreme kind thatits victims are often unable to detect their own unreliability (that is, they continue tobelieve they are reliable when in fact they are not). He comes to believe that the proba-bility that a person has remained cognitively reliable given that they have taken this drugis low or inscrutable. That is, if we let XX also stand for the statement that the man hastaken the drug, then P(R ⁄XX) is low or inscrutable. Then the man has a defeater for R,specified to himself.

The XX case is the most widely cited analogy used to support the Defeater Thesis.Other cases are also used: what is important to note here is that the Defeater Thesis isdefended, not by the use of any principle, but rather on the basis of analogies (Plantinga,‘Reply’, 240).

3. Defense of the Third Premise

Plantinga defends the third premise by arguing that, if the naturalist has a defeater for R,this generates a defeater for the rest of his beliefs as well (‘Introduction’,12). The reason isthat all of the naturalist’s beliefs are products of his cognitive faculties, which constitutetheir source. Once the reliability of that source comes into question, so do the beliefs gen-erated by the source. Moreover, the defeater for R that the naturalist acquires cannot itselfbe defeated, since everything that could be a defeater-defeater is itself subject to defeat.

4. Objections to EAAN

Let us now consider some objections to EAAN. My goal here is not to settle anything,but just to give readers a taste of the discussions that EAAN has provoked.

Obviously, I will only be able to cover a small sample of the objections that have beenmade. And for those objections I do describe, I won’t be able to do justice to the detailand sophistication with which they have been proposed. Instead, I will content myselfwith introducing two important categories of objection: objections to the Defeater The-sis, and Tu Quoque objections.

5. Objections to the Defeater Thesis

Most of the controversy regarding the argument has focused on the Defeater Thesis.There has been one main worry that critics have had about this claim. The objections toit that we will describe are manifestations of this worry, which can be expressed as



follows: what exactly is the connection between the naturalist’s acceptance of the Proba-bility Thesis on the one hand, and her acquisition of a defeater for R on the other?

One natural expression of this worry is the Perspiration Objection (Plantinga, ‘Natural-ism Defeated’).

The Perspiration Objection. ‘Let F be the claim that the function of perspiration is to coolthe body. Now, the probability of F given (just) N&E is also low. But surely it would beabsurd to claim that this gives the naturalist a defeater for the belief that F is true. Thus,it is also absurd to claim that the naturalist has a defeater for R in virtue of accepting theProbability Thesis.’

We can think of the Perspiration Objection as putting forward a certain analogy; onlythis time, unlike the case of EAAN, the analogy is put forward, not to defend the Defea-ter Thesis, but rather to attack it. In other words, this objection can be seen as an argu-ment by analogy for the falsity of the Defeater Thesis.

Does the Perspiration Objection succeed? I think not. More specifically, it will succeedonly if the perspiration case is sufficiently similar, in epistemically relevant respects, to theEAAN case (perhaps by being at least as similar to the EAAN case as the latter is to theXX case). I don’t have the space to go into this in detail, but it seems clear to me thatthis is false, and hence that the Perspiration Objection fails15; nevertheless, it does suggesta helpful approach to evaluating the Defeater Thesis: look for hypothetical cases in whichseeing that a probability is low or inscrutable does not yield a defeater, and which are atleast as strongly analogous to EAAN as is the XX case (Talbott and Wielenberg adopt thisstrategy). If there are such cases, they would seriously undermine the support on whichthe Defeater Thesis rests.

A plausible suggestion is that there is no defeater in the perspiration case because thenaturalist has other beliefs relevant to the function of perspiration, beyond just N&E, andthe probability that the function of perspiration is to cool the body relative to these otherbeliefs is high. So could not the naturalist appeal to other beliefs to raise the probabilityof R? This thought leads naturally to the following objection (Plantinga, ‘NaturalismDefeated’).

The ‘Can’t the Naturalist Just Add a Little Something?’ Objection. ‘The naturalist believesmany things besides N&E, such as R itself, or the proposition L that ‘‘we have won theevolutionary lottery’’. Relative to N&E conjoined with these other beliefs, the probabil-ity of R is very high, and thus the naturalist need not have a defeater in virtue of accept-ing the Probability Thesis.’

Plantinga has argued that this objection is very implausible, for one cannot escape hav-ing a defeater for a belief just in virtue of the fact that one already has that belief(‘Reply’, 222). Otherwise, it would be impossible for anyone to acquire a defeater forany belief at all. Plantinga also notes that appealing to L is dubious on the face of it: hesuggests that it would be like the response of a theist who hears an argument against theexistence of God on the basis of the problem of evil, and then says that although he cansee that the existence of God is unlikely given the vast quantity of evil in the world, heis nevertheless prepared to continue believing in God because he thinks we have wonthe ‘Divinity lottery’, and there really is such a person as God after all (‘Reply’, 223).

The objection above does not seem very compelling, but it does suggest a strategy forresponding to EAAN. That strategy is to come up with a proposition, X, which the nat-uralist believes, and which is such that P(R ⁄N&E&X) is high. This is not enough, how-ever: we also want X to be such that, if P(R ⁄ N&E&X) is high, the naturalist whosees this does not have a defeater for R in virtue of seeing that P(R ⁄N&E) is low orinscrutable. Following Plantinga, we will say that a proposition X is a defeater-deflector of



EAAN just in case it satisfies both of the above conditions (‘Reply’, 224). An importantquestion can now be expressed as follows: are there any defeater-deflectors of EAAN? Ifso, which ones? This is known as the Conditionalization Problem for EAAN (Plantinga,‘Reply’, 220–25).

A defeater-deflector of EAAN is a proposition that is naturally thought of as providingevidence for R. However, Plantinga and others hold that, in addition to propositionalevidence, beliefs can also be warranted in virtue of nonpropositional evidence (Bergmann,‘Commonsense Naturalism’,65). Such beliefs are typically held in the basic way, in thatthey are not based on any other beliefs. On this sort of view, for example, the experienceI have when it appears to me that there is a computer in front of me is nonpropositionalevidence, for me, that there is a computer in front of me.

That may be so, you think: but what does this have to do with EAAN? Well, onebelief that appears to be held in the basic way is R itself. It is an example of what Tho-mas Reid called first principles (Bergmann, ‘Commonsense’, 66). Now, denying such prin-ciples, thought Reid, elicits in us the emotion of ridicule, which serves the function ofhelping us to avoid doubt in these principles. Perhaps, then, the emotion of ridicule can,at least in some circumstances in which it is experienced, be seen as nonpropositional evi-dence for belief in R (Bergmann, ‘Commonsense’, 68).16 This leads to the followingobjection:

The Nonpropositional Evidence Objection. ‘Even if R has low probability on all the avail-able propositional evidence, the naturalist could still have nonpropositional evidence forR which makes it rational to continue to hold onto R. Hence, the naturalist need nothave a defeater for R merely in virtue of accepting the Probability Thesis.’

One challenge to this objection comes from considering the XX case (Plantinga,‘Reply’, 232). Recall that this is a widely cited analogy used to support the DefeaterThesis, and EAAN proponents typically assume that it is indeed analogous, in all relevantepistemic respects, to the case of the naturalist who accepts the Probability Thesis. Inwhat follows, let us grant this assumption for the sake of argument.17 Now, suppose Ithink I have taken XX, and I have nonpropositional evidence for R. Am I rational incontinuing to hold onto belief in R on the basis of this evidence? My own intuition says‘No’. For I believe that, if the drug were to render R false in my case, I would still quitelikely have exactly the same nonpropositional evidence for R (except that this evidencewould then be misleading); if I reflect on this, I will surely have serious doubts aboutwhether this nonpropositional evidence is trustworthy, and so I will not be able to escapedefeat. By analogy, the EAAN proponent will argue, the naturalist does not escape defeatby virtue of nonpropositional evidence for R.

6. Tu Quoque Objections

EAAN was put forward to show that theism has a certain advantage over naturalism.Some have challenged this claim, by arguing that, if EAAN is sound, then theism facesthe same kind of self-defeat as that with which naturalism is charged in EAAN. Objec-tions of this type generally go by the label ‘Tu Quoque Objection’. An early version ofthis is the following (Ginet, 407):

The Austere Theism Objection. ‘The theist believes that there is a God: an omniscient,omnipotent and supremely benevolent being. This means that, unless his powers of infer-ence are severely limited, the theist also believes what is entailed by theism, namely thatthere is a very powerful being. Call this latter belief austere theism, (henceforth, A). Now,the conditional probability P(R ⁄ A) is very hard to determine, and so the most plausible



opinion about its value is that it is inscrutable, and hence low or inscrutable. Since everytheist is an austere theist, it follows that any theist who sees that this probability is low orinscrutable has a defeater for R.’18

An obvious rebuttal to the Austere Theism Objection is that the theist surely believesmuch more than just austere theism (Ginet, 407). If we let T stand for traditional Christiantheism, then T will include a range of beliefs besides A. Perhaps, then the theist is savedfrom self-defeat in virtue of the fact that P(R ⁄T) is high, even if P(R ⁄ A) is inscrutable.

This response sounds promising, but there are two problems with it. To begin with,the naturalist can appeal to similar considerations, by claiming that he too believes morethan N&E, that relative to his expanded set of beliefs the probability of R is very high,and that this saves him from the defeat with which he is threatened (Ginet, 407). Unlessthere is a reason to think that this kind of move is acceptable for the theist but not thenaturalist, EAAN will fail to secure a distinctive advantage for theism over naturalism.

The second problem is that of coming up with a good reason for thinking thatP(R ⁄T) is high. One strategy is that of appealing to the perfection and goodness of God:it might be inferred, from the premise that God exists and has these attributes, thathe has, most likely, given us faculties which yield mostly true beliefs. This is certainlya natural thought; it is reminiscent of Descartes’ claim that a perfect God is not adeceiver (Roeber).19

One problem with this inference is that it relies on the presupposition that God doesnot have a morally sufficient reason for creating us with unreliable faculties. This presup-position is initially plausible, because it is hard to think of such a reason. However, it cancome to seem doubtful in the light of responses to the problem of evil that are widelyendorsed by theists, and which are initially plausible in their own right. Let’s examine thisin some more detail.

Theists have rejected some forms of the evidential argument from evil on the groundsthat, for all we know, God has morally sufficient reasons for permitting horrible evils,even if we can’t tell what these are. This approach to the argument from evil goes by thelabel ‘skeptical theism’ (Bergmann, ‘Skeptical Theism and Rowe’s New Evidential Argu-ment from Evil’, 278). We can characterize this as the conjunction of theism with theclaim that we have no good reason to suppose that the goods, evils, and connectionsbetween goods and evils of which we are aware, are representative of the goods, evils,and connections between goods and evils that there actually are (Bergmann, ‘SkepticalTheism’, 279). As Bergmann points out, this second conjunct has considerable initialplausibility, even independently of theism, since ‘it wouldn’t be the least bit surprising if[axiological] reality far outstripped our understanding of it’ (‘Skeptical Theism’, 284).20

Return to the claim that there is no morally sufficient reason for God to create us withunreliable faculties. How could we be justified in accepting this claim? If skeptical theismis correct, then there could, for all we know, be some great good, of which we are una-ware, but which is inextricably connected with our being massively unreliable, and whichgives God a morally sufficient reason to make us that way (Roeber, 317–19). To theextent that skeptical theism seems reasonable, the plausibility of this claim is undermined,and hence so is the inference from God’s goodness to our reliability.

Plantinga’s strategy for arguing that P(R ⁄T) is high is different from the one we havejust been considering, in that he appeals to the religious tenet that ‘God is the premierknower, and has created us human beings in his image, an important part of whichinvolves his endowing them with a reflection of his powers as a knower’ (Warrantand Proper Function, 236); thus, the Christian has reasons to think that humans haveknowledge. But a belief can only count as knowledge if it is produced by a reliable



belief-forming faculty.21 And thus the theist has no reason to doubt R that correspondsto the EAAN defeater (Warrant and Proper Function, 236).

One challenge to this argument stems from the fact that it is a part of theism thathuman nature can be corrupted; even if humans were originally made in the image ofGod, all kinds of things could happen to them which lead to their cognitive malfunc-tioning. For example, such malfunctioning could be caused by the free actions of cre-ated agents, whether these are humans or supernatural agents like Satan (Lehrer, 29);and God might permit this malfunctioning to occur either because of the intrinsic valueof creaturely free will or, if skeptical theism is plausible, because of morally sufficientreasons that are beyond our ken (Roeber, 318). At any rate, this second strategy forarguing that P(R ⁄T) is high will be convincing only if such possibilities can be ruledout.

The reflections above suggest something like the following argument.The Satanic Deception Objection.22 ‘What is P(R ⁄T)? To evaluate this, let us consider a

hypothetical population on a planet a lot like earth: this will help us to avoid any unduebias arising from our prior conviction that our own cognitive faculties are reliable. Assum-ing that these creatures have and change beliefs, that God exists, and that somethingroughly similar to the Christian story is true of them, what is P(R ⁄T) specified to them?

‘Let S be the following statement(S) On the basis of morally sufficient reasons which are beyond our ken, God allows

Satan to create incredible amounts of deception among these creatures, for a significantperiod of time, leading to the massive malfunctioning of their cognitive faculties duringthat time.Then the probability calculus yields the following formula:

PðR/TÞ ¼ PðR/SÞPðS/TÞ þ PðR=�SÞPð� S/TÞ:

Now, P(R ⁄S) is surely very low. And, since theists agree that God has allowed Satan andhumans to create all kinds of evil on the earth, it is hard to see how S can be ruled out,given theism. In the light of our cognitive limitations, and the infinite gap between ourknowledge and that of God, we do not know how likely it is that God has morally suffi-cient reasons to allow Satan to deceive these creatures. Thus, P(S ⁄ T) is inscrutable, andso P(R ⁄T) is inscrutable as well. Since this is true with respect to the hypothetical popu-lation, it must be true with respect to us as well.

‘Note that if the theist sees this, she will have a defeater for R, on the basis of exactlythe same reasons that lead the EAAN proponent to conclude that the naturalist has adefeater for R.’

This argument, if successful, shows that theism can lead to the same kind of universalskepticism as that with which the naturalist is threatened in EAAN, assuming the latterargument is sound. Does the EAAN proponent have a good reply? One response mightbe to develop a version of EAAN in which P(R ⁄N&E) is shown to be low, rather thanjust low or inscrutable.23 If there is no corresponding reason to think that P(R ⁄T) is low,then theism appears to escape facing a problem of self-defeat in exactly the same way thatnaturalism does. Some sort of Tu Quoque response might still be made, but it would notbe as natural or straightforward as the one we have considered above.

Can there be an argument to the effect that P(R ⁄N&E) is low, rather than low orinscrutable? In more recent work, Plantinga has already developed such an argument(Plantinga, ‘Self-Profile’).24 Is there a natural Tu Quoque Objection to this newargument? That seems to me an important question.



Another response would be to appeal to further beliefs endorsed by Christian theologyto show that the Christian theist need not have a defeater for R. For example, Plantingaargues that the Christian will believe that, by virtue of her accepting Christian faith, theaction of the Holy Spirit within her is progressively ameliorating the effects of sin on herhuman nature, and is restoring her to the image of God in which she was created, a partof which involves her reflecting God’s powers as a knower and having reliable cognitivefaculties (‘Respondeo’,337). This kind of response concedes that God could allow vastamounts of deception to occur among humans, while nevertheless emphasizing that thosewho accept Christianity are saved from this fate.

7. Further Directions for Research

Much discussion of EAAN is polemical, and focused on proposing rebuttals to the argu-ment, or proposing counter-rebuttals to those rebuttals. Little consensus seems to beemerging in this discussion, and so, I think, the challenge of EAAN is still with us (Mirza,126). Where do we go from here?

I suggest that, rather than merely attacking or defending EAAN, philosophers spendmore time trying to carefully and systematically understand the intuitions that make theargument so compelling to its proponents. This approach is familiar from other topics inphilosophy. For example, most epistemologists want to refute skepticism, but they are alsointerested in explaining why it seems compelling to so many. In fact, very often a refuta-tion of skepticism will be seen as unsatisfactory if it seems too easy, that is, if the refutationmakes it seem a mystery that anyone would be worried about skepticism in the first place(Reed, ‘A New Argument for Skepticism’). Ideally, a refutation of EAAN will meet asimilar standard: such a refutation should also yield some insight into why the argument,when properly understood, is intuitively compelling to at least some philosophers.

The Defeater Thesis is at the heart of EAAN, and the most widely cited defense of thisthesis involves an analogy with the XX case. But few philosophers have tried to challengeor investigate the intuition that is meant to be elicited by the XX case, namely the judg-ment that the subject in that case has a defeater for R. It is generally just granted, even ifonly for the sake of argument, that this intuition is sound. I conjecture that a deeperunderstanding of this case will lead to one of two results: either the intuition will berejected, in which case the Defeater Thesis will be undermined; or else we will be ableto determine which epistemic features of the XX case best explain the intuition. In thelatter case we can investigate whether or not the EAAN case has the very same features,and hence whether or not it is genuinely analogous to the XX case.

Acknowledgement

Thanks to Kevin Sharpe and an anonymous reviewer for helpful comments.

Short Biography

Omar Mirza is Associate Professor of Philosophy at St Cloud State University in StCloud, Minnesota. He has been a Visiting Fellow at the Center for the Philosophy ofReligion at the University of Notre Dame, and has previously held posts at GeorgeWashington University, Washington D.C. and Luther College in Decorah, Iowa.

Omar holds a doctorate in Logic and the Methodology of Science from U.C. Berke-ley, and his interests lie in epistemology, logic, and the philosophy of religion; his work



on the evolutionary argument against naturalism has recently been published in Philosophi-cal Studies, and in the latest edition of A Companion to Epistemology (ed. Dancy, Sosa,Steup).

Notes

* Correspondence: Department of Philosophy, St Cloud State University, Centennial Hall 365, 720 4th AvenueSouth, St Cloud, MN, 56301, USA. Emails: [email protected] and [email protected].

1 This is not to say that Plantinga wishes to criticize the theory of evolution itself. That theory, he says, is perfectlycompatible with theism. Rather, it is the conjunction of naturalism and evolutionary theory that Plantinga finds to beself-defeating, under certain conditions (‘Introduction’, 1).2 This means that there is no self-defeat problem that arises for theism in the same sort of way as it does for natu-ralism in EAAN; Plantinga’s arguments on this point leave open the possibility that there is some other, very differ-ent, way in which theism is self-defeating.3 Note that it is not a part of the notion of defeater that a defeater itself has to be rationally held. A defeater canbe as irrational a belief as one pleases. For example, suppose that I acquire the belief that there exists a Cartesian evildemon, and I acquire it by way of misunderstanding Descartes: then my belief ‘There exists a Cartesian evil demon’is a defeater, for me, of my belief that I am typing this at my computer right now, even though it is wholly irratio-nal; the reason is that given that I believe in a Cartesian evil demon, it is irrational for me also to believe that I amtyping.Alston offers criticisms of Plantingas suggestion that an irrational belief can function as a defeater (‘Plantinga, Natur-alism, and Defeat’, 186–95), and Plantinga replies in the same volume (‘Reply’, 274).4 As will become clear, these ‘easily realized conditions’ are that the naturalist should accept evolutionary theory,and the Probability Thesis (to be described below).5 Strictly speaking, this should read ‘The beliefs produced by human cognitive faculties are for the most part trueover some significant range of their operation’. This qualification is necessary, because there will be various domains rela-tive to which human cognitive faculties are unreliable (Plantinga, Warrant and Proper Function, 216–17).6 What exactly is this defeater? It is not N&E, but rather the conjunction of N&E with the Probability Thesis(Plantinga, ‘Reply’, 206).7 This is not intended to be a prescription for how the naturalist who accepts the Probability Thesis ought tochange his or her beliefs. It merely indicates the belief changes to which the naturalist is rationally committed byvirtue of belief in naturalism; if these belief changes seem absurd, note that EAAN is akin to a reduction ad absurdumof naturalism. If there is a prescription involved in EAAN, it is that one should not be a naturalist.8 Objective probability is analyzed by Plantinga in terms of logical probability (Warrant and Proper Function, 162).9 This is one way to understand Quine’s statement that ‘creatures inveterately wrong in their inductions have apathetic but praiseworthy tendency to die before reproducing their kind.’ (126)10 Stephen Stich, for example, has challenged the view that our reliability is in any way guaranteed by our havingsurvived and evolved (56).11 Clearly, Plantinga thinks that materialists should hold that beliefs are neural states or processes. In private com-munication, he has mentioned that some version of EAAN will still be cogent even on other materialist accounts ofwhat beliefs are.12 This last possibility is normally discussed by philosophers of mind under the heading ‘semantic epiphenomenalism’.13 The appropriateness of this estimate can be illustrated by putting some actual numbers into the formula andcomputing the result for P(R ⁄ N&E). Of course, trying to come up with accurate numerical values for these proba-bilities is absurd, but the fiction that we have such values can help in understanding why the Probability Thesis isdefensible.So let us say that P(�C ⁄ N&E) = 0.7, and therefore that P(C ⁄ N&E) is 0.3; let P(R ⁄ N&E&�C) = 0.2. Then, evenif we set P(R ⁄ N&E&C) to the value of 1 (a concession, since Plantinga has argued this is at best moderately high),P(R ⁄ N&E) comes to 0.44, which is less than ½, and is hence low.14 In more recent work, Plantinga has given a new argument for the Probability Thesis which supports the stron-ger conclusion that P(R ⁄ N&E) is low, rather than the conclusion that it is low or inscrutable; he writes that ‘I’dlike to give an argument for [the Probability Thesis], and argument somewhat different from (and, I hope, superiorto) the arguments I’ve given for it elsewhere.’ (‘Self-Profile’, 175). However, most presentations of EAAN defendthe Probability Thesis along the lines described in this paper, and hence that has been our focus.15 One way to see this is to note that the defeater for R that the naturalist is said to acquire in EAAN is plausiblysupposed to be an undercutting defeater (which works by casting doubt on the trustworthiness on the source of thebelief R), while there is no plausible way to construe the naturalist as having an undercutting defeater for F in vir-tue of seeing that P(F ⁄ N&E) is low or inscrutable. This response to the Perspiration Objection is developed indetail by Omar Mirza (‘A User’s Guide to the Evolutionary Argument Against Naturalism’).



16 This idea will initially seem counterintuitive to most people. Baron Reed objects to it (‘Epistemic CircularitySquared? Skepticism About Common Sense’), and Michael Bergmann replies to the objection in the same journal(‘Epistemic Circularity and Common Sense: A Reply to Reed’).17 This assumption is typically ignored or conceded in discussions of EAAN, but it might be viewed as controver-sial, as a reviewer for Philosophy Compass has rightly pointed out. In the conclusion of this paper, I note theimportance of investigating the intuitions elicited by the XX case, as a preliminary to determining whether or notthis case is genuinely analogous to the case of the naturalist in EAAN.18 The Tu Quoque Objector is, of course, not committed to this claim. He is trying to show that, if EAAN issound, the EAAN proponent is committed to this conclusion, and hence is not in a position to claim that theismhas a serious advantage over naturalism.19 To the best of my knowledge, Plantinga does not appeal to this inference anywhere. However, not only is thisa natural first thought about how the theist could argue that P(R ⁄ T) is high, but it is also a good way to introducethemes that will be used in stating the next version of the Tu Quoque Objection, and hence I begin with it.20 The viability of this kind of approach is challenged by Richard Gale (208).21 This follows from Plantinga’s own analysis of knowledge, and also from other externalist accounts of knowledge(Warrant and Proper Function, 17).22 I am not aware of anyone presenting the Tu Quoque Objection in exactly this form before, but I have put ittogether by combining ideas from a number of commentators, especially Fales, Lehrer, and Roeber.23 All versions of the Tu Quoque Objection so far have argued that the probability of R on the relevant beliefs ofthe theist is inscrutable, rather than low. Roeber, for example, calls his argument the ‘Inscrutability ArgumentAgainst Theism’.24 This is beyond the scope of this paper.

Works Cited

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——. ‘Commonsense Naturalism.’ Naturalism Defeated? Essays on Plantinga’s Evolutionary Argument Against Naturalism.Ed. James Beilby. Ithaca, London: Cornell University Press, 2002. 61–90.

——. ‘Epistemic Circularity and Common Sense: A Reply to Reed.’ Philosophy and Phenomenological Research 73.1(2006): 198–207.

Dancy, Jonathan, Ernest Sosa, and Matthias Steup, eds. A Companion to Epistemology. Malden, MA: Wiley-Black-well, 2010.

Fales, Evan. ‘Darwin’s Doubt, Calvin’s Calvary.’ Naturalism Defeated? Essays on Plantinga’s Evolutionary ArgumentAgainst Naturalism. Ed. James Beilby. Ithaca, London: Cornell University Press, 2002. 43–58.

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——. ‘A New Argument for Skepticism.’ Philosophical Studies 142 (2009): 91–104.Roeber, D. Blake. ‘Does the Theist Have an Epistemic Advantage over the Atheist? Plantinga and Descartes on

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The Evolutionary Argument Against Naturalism