bookmark_borderAdolf Grünbaum on Determinism and Reason

” The causal generation of a belief does not, of itself, detract in the least from its truth. My belief that I address a class at certain times derives from the fact that the presence of students in their seats is causally inducing certain images on the retinas of my eyes at those times, and that these images, in turn, then cause me to infer that corresponding people are actually present before me. The reason why I do not suppose that I am witnessing a performance of Aida at those times is that the images which Aida, Radames, and Amneris would produce are not then in my visual field. The causal generation of a belief in no way detracts from its veridicality. In fact, if a given belief were not produced in us by definite causes, we should have no reason to accept that belief as a correct description of the world, rather than some other belief arbitrarily selected. Far from making knowledge either adventitious or impossible, the deterministic theory about the origin of our beliefs alone provides the basis for thinking that our judgments of the world are or may be true. Knowing and judging are indeed causal processes in which the facts we judge are determining elements along with the cerebral mechanism employed in their interpretation. It follows that although the determinist’s assent to his own doctrine is caused or determined, the truth of determinism is not jeopardized by this fact ; if anything, it is made credible.”
Adolf Grünbaum, “Free Will and Laws of Human Behaviour”, American Philosophical Quarterly, 1971
 
HT: Justin Schieber

bookmark_borderThe VICTIMs of Christian Apologetics

My latest video, “The VICTIMs of Christian Apologetics: The Things Apologists Falsely Say Depend on God, But, if God Exists, God Depends on Them,” is now available on YouTube. It is a narration of some of the many hundreds of PowerPoint slides I created in preparation for my recent debate with Frank Turek on naturalism vs. theism.
[youtube]https://youtu.be/xXWTc6-toDo[/youtube]
This video presentation is a (roughly) 2 hour 30 minute critique of Frank Turek’s latest book, Stealing from God: Why Atheists Need God to Make Their Case. Turek accuses atheists of stealing from God in order to argue against God. How do atheists steal from God when arguing against God’s existence? According to Turek, this is summed up by the acrostic CRIMES (Causality, Reason, Information and Intentionality, Morality, Evil, and Science). So his argument is that atheists must assume each of those things, but each of those things in turn presuppose God’s existence.
For each letter in CRIMES, atheism can steal these concepts from God if and only if: (a) atheism is logically incompatible with the concept represented by that letter; and (b) positing an all-powerful God explains that concept, not just assumes it. But as I will explain, each letter in CRIMES fails one or both conditions.
Now, since repeatedly accusing an innocent person of a crime harms the accused, I’m going to frame my response as an acrostic of my own: VICTIM (Value, Induction, Causality, Time, Information and Intentionality, and Morality). Instead of talking about crimes, what we instead need to talk about are the VICTIMs of Christian apologetics. The VICTIMs of Christian apologetics are things which Christian apologists falsely claim depend on God, but the truth is that God depends on them.
Since the video is quite long and detailed, the following serves as a handy index:
Counter Apologist went through the effort to list the topics covered and give time-stamps/links for each topic which you can find below:

HT: Counter-Apologist for creating the index

bookmark_borderWeighing Theistic Evidence Against Naturalistic Evidence

In the next-to-last paragraph of his book, C.S. Lewis’ Dangerous Idea: In Defense of the Argument from Reason, Victor Reppert makes a very interesting statement:

However, I contend that the arguments from reason do provide some substantial reasons for preferring theism to naturalism. The “problem of reason” is a huge problem for reason, as serious or, I would say, more serious, than the problem of evil is for theists. (emphasis mine)

I think this is a very interesting statement for two reasons. First, Reppert acknowledges that the so-called “problem of evil” — which is probably misnamed (see here) — is an evidential problem for theism. All by itself, that is a significant concession that is all too rare among theistic philosophers. But second (and more important), Reppert claims that naturalism’s ‘problem of reason’ is as big of a problem, if not a bigger problem, for naturalism as the ‘problem of evil’ is for theism. I want to focus on this second feature of interest about Reppert’s statement.
I recently asked, “Why Do So Many People Have a “Winner Takes All” Approach to Evidence about Gods?” Suppose you agree with my conclusion that there can be evidence for false propositions, so there can be evidence for atheism if God exists, and so there can be evidence for theism if God does not exist.
As soon as you admit that possibility, you have to be prepared to confront another possibility. How do you weigh competing items of evidence, especially when we don’t have numerical probability values (or likelihoods or Bayes’ factors) to work with? Here are two versions of this problem.
(1) Weighing Two Individual Items of Evidence
Suppose you have two items of evidence, E1 and E2, and two rival hypotheses, H1 and H2. E1 is evidence favoring H1 over H2, i.e., Pr(E1 | H1)  > Pr(E1 | H2). Let B1 the “Bayes’ factor” for E1 , i.e., the ratio of Pr(E1 | H1)  to Pr(E1 | H2). E2 is evidence favoring H2 over H1, i.e. Pr(E2 | H2) > Pr(E2 | H1). Let B2 be the Bayes’ factor for E2, i.e., the ratio of Pr(E2 | H1) to Pr(E2 | H2). If E1 is stronger evidence for H1 than E2 is evidence for H2, then B1 > 1/B2. Likewise, if E2 is stronger evidence for H2 than E1 is evidence for H1, then 1/B2 > B1. But how do you show that?
In some cases, it may be possible to show this is true by definition. For example, in my F-inductive argument from consciousness, I argue that Pr(consciousness | theism) =1 because theism entails the existence of consciousness. Now compare that result to a very weak argument against theism, the argument from scale. I have argued before that, as an argument against mere theism, the evidence of scale provides very weak evidence favoring naturalism over theism. So it seems obvious that if Pr(consciousness | theism) = 1, then consciousness is much stronger evidence for theism than scale is against it.
Or consider Paul Draper’s evidential argument from biological evolution. The key insight to understanding that argument is this. It is really an argument against special creationism, combined with a rigorous argument that special creationism is a viable auxiliary hypothesis to theism. In other words, theism provides a significant antecedent reason to expect that special creationism is true conditional upon the assumption that theism is true, where “antecedent” emphasizes the idea that we are abstracting away all of our evidence from biology. Draper’s evidential argument from biological evolution argues that Pr(special creationism | naturalism) = 0, whereas Pr(special creationism | theism) >= 1/2. Now suppose you have some extremely weak argument for theism, such as the argument from beauty. I don’t think beauty provides any evidence for theism, but for the sake of argument let’s pretend that it does. In that case, it would be obvious that the falsity of creationism is much stronger evidence against theism than beauty is evidence for it.
Not all comparisons of evidence will involve cases where at least one hypothesis entails neither the evidence to be explained nor the denial of the evidence to be explained. In those cases, it seems to me it will be more difficult, possibly impossible, to justify an objective comparison of evidential strength. (Whether it is impossible or merely difficult will have to be determined on a case-by-case basis.)
(2) Weighing Cumulative Cases Against One Another
Suppose now you have two “real” cumulative cases done the right way. In favor of H1, you have items of evidence E1 through E5. In favor of H2, you have items of evidence E6-E10. For example, let H1 be theism and H2 be naturalism. Then let our items of evidence be:
E1: the contingency of the universe
E2: the beginning of the universe
E3: the life-permitting conditions of the universe
E4: consciousness
E5: intentionality
E6: the hostility of the universe to life
E7: biological role of pain and pleasure
E8: falsity of special creationism
E9: mind-brain dependence
E10: psychopathy
You believe that E1-E5 are individually and collectively evidence favoring theism over naturalism. Likewise, you believe that E6-E10 are individually and collectively evidence favoring naturalism over theism.
As before, we’ll use “B” to represent the Bayes’ factor. Let B1-5 represent the ratio of Pr(E1 & E2 & E3 & E4 & E5 |T) to Pr(E1 & E2 & E3 & E4 & E5 |N). Let B6-10 represent the ratio of Pr(E6 & E7 & E8 & E9 & E10 | T) to Pr(E6 & E7 & E8 & E9 & E10 | N).
How in the world are you supposed to show that B1-5 > 1/B6-10?
(3) Is Naturalism’s ‘Problem of Reason’ as Big or Bigger than Theism’s ‘Problem of Evil’?
Let us now return to Reppert’s statement I quoted at the beginning of this post:

However, I contend that the arguments from reason do provide some substantial reasons for preferring theism to naturalism. The “problem of reason” is a huge problem for reason, as serious or, I would say, more serious, than the problem of evil is for theists. (emphasis mine)

Reppert does not attempt to defend this claim in his book, but in fairness we should note the argument from reason is a neglected topic in the philosophy of religion. It seems reasonable to devote an entire book just to (re-?)introducing the argument and defending it. But it would be a major accomplishment in the philosophy of religion, I think, if Reppert were able to successfully defend this claim. Perhaps he can devote his considerable philosophical talents to this task in a future book.

bookmark_border“The Argument from Reason” (2)

(redating post originally published on 14 December 2011)
At 349, Reppert says: “We ought to draw the conclusion if we accept the premises of a valid argument”.
This is obviously wrong. Suppose, to take the worst case, that my beliefs contradict one another. If we are supposing classical logic — as Reppert clearly is — then, from my contradictory beliefs, using Reppert’s principle, I ought to infer that every claim is true. But, even though there IS a valid argument from premises I accept to an absurd conclusion, I ought NOT to “draw” the absurd conclusion. Rather, what I ought to do is to go back and examine my premises (my set of beliefs). Of course, this point is perfectly general: it is not just a point about the special case in which my beliefs are contradictory. Whenever I notice that my beliefs entail some further belief, it is an open question whether I ought to accept the further belief (“draw” the conclusion), or whether I should re-examine my premises (my set of already held beliefs).
This is not a minor quibble. Reppert throughout writes in a way that conflates logic and inference. It is one question what is entailed by beliefs that I already hold (this is a question of logic); it is quite another what I ought to infer — how I ought to change the beliefs that I hold — given the beliefs that I already hold. (In *Change in View*, Gil Harman notes other good reasons for not conflating logic and inference. For insistence, there is clearly a principle of “clutter avoidance” that applies to inference: you should only make the effort to draw inferences from given beliefs that you hold if there is some point to your so doing. “p” entails “p or q”; but, typically, there is no point in trying to enlarge your stock of beliefs by drawing inferences that conform to this logical principle. On the other hand, there is no principle of “clutter avoidance” that applies to logic: that one proposition entails another is utterly independent of our interests, cognitive economy, and so forth.)
In his discussion of “the argument from the psychological relevance of logical laws”, Reppert writes (380): “… laws of logic pick out ways of thinking that are correct regardless of place, time, or even possible world”. Not so. Laws of logic do NOT pick out “ways of thinking”. Laws of logic concern logical relations between propositions (entailment, inconsistency, etc.) Ways of thinking concern the revision of belief (possibly under the impact of new information). Connections between these topics are indirect. True enough, a collection of beliefs can be criticised because of the logical relations that hold between the contents of the beliefs: for instance, a collection of beliefs can be logically inconsistent. But this observation has nothing to say about the revision of belief: it cannot tell us, for example, which beliefs ought to be given up in order to return the system of beliefs to consistency. (Perhaps it tells us that we ought to revise our beliefs. But even this advice is not unconditional. If the inconsistency can be quarantined, and if it doesn’t have significant behavioural consequences, then it may fall so low on the list of cognitive imperatives as never to receive attention.)
Some of these difficulties can be avoided if, instead of talking about beliefs, we talk about theories. Since theories are identified by their non-logical axioms, they are not dynamic–and so we don’t get into the kinds of difficulties that emerge if we talk about beliefs.

bookmark_border“The Argument from Reason”

(Redating post originally published on 8 December 2011)
A couple of comments on Reppert “The Argument from Reason” in Craig and Moreland (ed.) Blackwell Companion to Natural Theology, 344-90. (I have a long list; I may post further comments later.)
1. At 368, Reppert argues: If the reference of our terms is indeterminate, then this has the disastrous consequence that we cannot reason to conclusions.
This is surely wrong. Reasoning can be purely formal. (If all flombs are bloops, and all bloops are shimbs, then all flombs are shimbs. The reasoning is impeccable. We can reason even if our terms have no meanings!) Moreover — and perhaps partly in consequence — so long as we restrict ourselves to a single context, and use the same word throughout, we can reason perfectly well even if our meanings are indeterminate. (If this is a rabbit, and that is a distinct rabbit, then there are at least two rabbits. Fine, regardless of Quinean indeterminacy in the meaning of “rabbit”!)
2. At 374, Reppert endorses an argument by Menuge, for the conclusion that our intentionality is the product of prior intentionality. This argument begins as follows:
1. If something has a purpose, then it is designed.
2. Intentionality has the purpose of guiding behaviour.
3. (So) Intentionality is designed.
This argument cannot be good … and, in particular, Reppert cannot think that it is good. After all, he does NOT think that God’s intentionality is designed.

bookmark_borderArguments from Reason

I’ve finally gotten around to starting Victor Reppert’s book, C.S. Lewis’s Dangerous Idea: In Defense of the Argument from Reason. As Reppert points out in one of his chapters, we can really think of the “argument from reason” as the name for an entire family of theistic arguments. Indeed, Reppert formulates six different versions of the argument from reason which, he says, can be combined to form a cumulative case.
Here are his six arguments.

  1. Argument from Intentionality
  2. Argument from Truth
  3. Argument from Mental Causation
  4. Argument from the Psychological Relevance of Logical Laws
  5. Argument from the Unity of Consciousness in Rational Inference
  6. Argument from the Reliability of Our Rational Faculties

What follows is Reppert’s formulation of each argument.
Argument from Intentionality

  1. If naturalism is true, then there is no fact of the  matter as to what someone’s thought or statement is about.
  2. But there are facts about what someone’s thought is about. (Implied by existence of rational inference.)
  3. Therefore, naturalism is false.

Argument from Truth

  1. If naturalism is true, then no states of the person can be either true or false.
  2. Some states of the person can be true or false. (Implied by existence of rational inference.)
  3. Therefore, naturalism is false.

Argument from Mental Causation

  1. If naturalism is true, then no event can cause another event in virtue of its propositional content.
  2. But some events do cause other events in virtue of their propositional content. (Implied by existence of rational inference.)
  3. Therefore, naturalism is false.

Argument from the Psychological Relevance of Logical Laws

  1. If naturalism is true, then logical laws either do not exist or are irrelevant to the formation of beliefs.
  2. But logical laws are relevant to the formation of beliefs. (Implied by existence of rational inference.)
  3. Therefore, naturalism is false.

Argument from the Unity of Consciousness in Rational Inference

  1. If naturalism is true, then there is no single metaphysically unified entity that accepts the premises, perceives the logical connection between them and draws the conclusion.
  2. But there is a single metaphysically unified entity that accepts the premises, perceives the logical connection between them and draws the conclusion. (Implied by existence of rational inference.)
  3. Therefore, naturalism is false.

Argument from the Reliability of Our Rational Faculties

  1. If naturalism is true, then we should expect our faculties not to be reliable indicators of the nonapparent character of the world.
  1. But our faculties do reliably reveal the nonapparent character of the world. (Implied by existence of rational inference.)
  1. Therefore, naturalism is false.

Since I’ve just started to read his book, I don’t have much to say other than this. Like many people, Reppert suggests that different arguments have more strength when considered as a cumulative case, as opposed to when each argument is considered individually. Also like many people, however, it appears that Reppert doesn’t (1) actually spell out the cumulative case argument or (2) defend the claim that the cumulative case is stronger. In his defense, perhaps he thought it was too obvious. But, if so, I disagree with him. It may be that his six arguments do combine to form a cumulative case, but that needs to be shown and not just asserted. (I trust Victor will correct me if I’m in error and he does do this in his book or elsewhere.)
As I’ve explained before, cumulative case arguments have a very natural and straightforward Bayesian interpretation (scroll down to “Cumulative Case Arguments” in the linked PDF file). The simplest way to explain it is this. Suppose you have two facts, F1 and F2, and you want to show that F1 and F2 combine to form a cumulative case favoring hypothesis H1 over hypothesis H2. How do you do this?
Let’s start with what not to do. You don’t do this by showing:
1. F1 favors H1 over H2.
2. F2 favors H1 over H2.
Instead, you need to show two things:
1. F1 favors H1 over H2.
2. F2 favors (H1 combined with F1) over (H2 combined with F1).
I think it’s an interesting question whether Reppert’s six arguments can be combined to form a cumulative case in this way.
For example, start with intentionality — let’s treat intentionality as F1. (As an aside, I wonder if the fact of intentionality is conditionally independent of the fact of consciousness. In other words, does it even make sense to suppose there is a state of affairs where consciousness exists, but intentionality does not? I don’t know. But let that pass.) Let’s just assume, for the sake of argument, that intentionality favors theism over naturalism. So we have:
1′. F1 favors T over N. [assumption]
Going out of order, let F2 be mental causation. If F1 and F2 are a cumulative case, then we need reason to believe the following is true.
2′. F2 favors (T combined with F1) over (N combined with F1).
The problem is that the truth of 2′ is far from obvious. If we’re including the fact of intentionality in our background knowledge — i.e., if we are already assuming that intentionality exists — then it’s far from obvious that mental causation adds much, if anything, to the case for theism and against naturalism. I’m inclined to believe this: the existence of consciousness is certain on the fact of intentionality. Furthermore, the existence of mental causation is very highly probable, if not certain, on the fact of consciousness. Ultimate metaphysical hypotheses like theism and naturalism don’t seem to change this at all, once we include intentionality (or consciousness) in our background knowledge. Therefore, 2′ is doubtful.
With that said, I must write that I am initially VERY skeptical of the argument from intentionality. I haven’t thought about it deeply, so take my comments with a grain of salt. But because I consider consciousness and intentionality linked, I don’t see how the argument from intentionality adds to the argument from consciousness. In Reppert’s defense, he might say, “It doesn’t. So go deal with the argument from consciousness!” Which would be a fair reply.
Okay, I said these would be some very preliminary thoughts.

bookmark_borderInput Requested: Facts about Mental Properties Which Might be Relevant to Theism and Naturalism

I’m interested in collecting a list of mental properties which might be relevant to theism and naturalism. Examples:

  • Consciousness
  • Intentionality
  • Reliability of Cognitive Mechanisms
  • Mind-brain dependence

What else have I missed?

bookmark_borderMelnyk, Goetz, and Taliafero on the AFR

Lately I have been doing a book revision and in the process reflecting on the “Great Debate” between Andrew Melnyk and the Christian philosophers Stewart Goetz and Charles Taliafero. Melnyk defends the thesis of the physical realization of the mental (PRM) and Goetz and Taliafero offer criticisms. Here are my thoughts so far. Comments would be welcome. Sorry for the length and apologies also that I am too lazy to put in references in this draft. The MTB thesis is the claim, broader than Melnyk’s specific one, that minds are in some sense reducible to, caused by, identical with supervenient upon, realized by…etc. the brain.
It appears that if PRM is true, it cannot be rationally believed!
“What this [PRM] seems to imply is that everything that occurs in our mental lives, including our beliefs, is ultimately explicable in terms of physical causation alone without any explanation of that which is irreducibly mental by something else which is irreducibly mental. If physicalism is true, it seems that the ultimate explanation of M’s belief that physicalism is true will mention only neural phenomena and/or more fundamental physical constituents. There will be no mention in that explanation of anything that is ultimately and irreducibly mental. So, even if there are irreducible contents of apprehensions and beliefs which are physically realized…physicalism entails that M believes that physicalism is true, not because his apprehensions of irreducible contents ultimately cause his belief with it irreducible contents but because physical (neural) realizers of those apprehensions causally produce physical realizers of that belief. In short, physicalism seems to entail that apprehensions of contents are explanatorily impotent. Given the truth of epiphenomenalism and the explanatory impotence of apprehensions of contents, why should any of us try to reason with other about anything with the hope of changing their beliefs by having them apprehend contents of conceptual entities (Goetz and Taliafero, 4)?”
This important and subtle “argument from reason” (AFR) must be explained carefully: A common view of rationality holds that what makes our beliefs rational is that we base them on reasons. That is, you rationally believe that P when, and only when, your belief that P results from having fairly considered the reasons for (and against) P and it seems to you that the reasons, on balance, are sufficient for the truth of P. For instance, if I want to know the capital of Mongolia, I pull down my atlas and see that the capital of Mongolia is Ulan Bator. My recognition that a standard reference book, which would be very unlikely to be wrong about such a fact, tells me that the capital of Mongolia is Ulan Bator seems to me sufficient reason to accept that claim. Hence, my belief is rational. The essence of this account of rational belief is that one irreducibly mental event, belief that P is explained by another irreducibly mental event, the apprehension of the reasons for P and their sufficiency for the truth of P.
If you ask Melnyk why he accepts PRM, then, like anyone else, he will give reasons that he holds are sufficient for the truth of his claim. Let’s call those reasons R1, R2, R3…Rn. Goetz and Taliafero argue that if PRM is true, Melnyk cannot hold PRM because of reasons R1, R2, R3…Rn. Suppose that Melnyk apprehends reasons R1, R2, R3…Rn (where we will assume that those reasons include the recognition that the other reasons are jointly sufficient for the truth of PRM). It follows that, since PRM is assumed true, the cause of Melnyk’s belief is not his mental apprehension of those reasons, but the physical realization of those mental apprehensions in his neural states. This is because, if PRM is true, the mental state “belief that PRM is true” is fully realized in a physical (neural) state. Further, that neural state is caused by other neural states, namely, the physical realizations of the apprehension of reasons R1, R2, R3…Rn.
The upshot is apparently that, on PRM, the mental act of understanding a reason is an epiphenomenon of the physical cause. To say that A is an epiphenomenon of B means that B causally determines A, but A does no causal work, either back on B or on anything else. So, on PRM it cannot be the mental act of understanding per se that explains the belief; rather, it is the physical realization of that act that does all the causal work. The mental act therefore just seems a useless appendage, an epiphenomenon. Hence, if PRM is true, then Melnyk cannot believe the truth of PRM because of the reasons he cites. Melnyk does not believe because of those reasons. Instead, his belief was caused by a sequence of neural, i.e. purely physical, events in his brain. But how can a belief be rational if it is not based on reasons? Melnyk’s belief that PRM is true seems to be like the breaking of a glass bowl when it is dropped onto a hard floor. Both belief and breakage seem to be caused by brute, blind force (to indulge in a bit of rhetoric), so neither the belief nor the broken bowl can be explained in terms of reasons.
It seems to follow from this argument that the truth of PRM precludes any rational basis for believing that PRM is true. This is because the truth of PRM precludes the possibility of having any reasons for believing it because it relegates all causes of belief to a sequence of physical causes. Surely, it seems, there must be something profoundly and irremediably wrong with a theory that, if true, insures that it cannot be rationally believed to be true!
I think that the AFR articulated in the above few paragraphs is Goetz and Taliafero’s strongest argument. However, I do not think that Melnyk replies to it adequately so I will now say what I think is wrong with it.
First, note that Goetz and Taliafero’s arguments, and practically all arguments against the MTB thesis, are a priori in nature, whereas the arguments for MTB are mostly empirical. Historically, a priori arguments have fared very poorly when opposed to empirical arguments. Philosophers will draw an a priori line in the sand and scientists will gleefully jump over it. The dismal track record of a priori claims against empirical ones provides some reason to doubt the cogency of arguments like those of Goetz and Taliafero.
Further, human beings would be most unfortunate if in fact a theory as important as PRM were true and could not be rationally believed. Goetz and Taliafero appear to concede that PRM could be true, but they hold that the truth of PRM would preclude rationally believing it by our standards of rational belief. However, if our standards of rational belief are such that they can preclude us from rationally believing an important theory that (we are assuming) is in fact true, then perhaps our standards of rational belief are deficient. Standards of rational belief are supposed to permit, not preclude, rational belief in true theories. If PRM is true—and, again, Goetz and Taliafero apparently concede that it could be—then this is a very important truth and there needs to be some way that we can rationally believe that it is true.
A reliability account of warrant would seem to fill the bill. According to reliabilism, all that matters is whether a belief-forming process reliably generates true beliefs. A belief that is formed by a reliable process is warranted and therefore a rational belief. The nature of the process is irrelevant. If I can reliably form true beliefs by rolling a pair of magic dice, then rolling the dice confers warrant on my beliefs. If we accept reliabilism, then it does not matter if Melnyk is caused to believe that PRM is true by a physical process. It only matters that the process was reliable in generating true beliefs, and the reliability of physical belief-forming processes can certainly be accommodated by PRM and would seem to generate no self-referential problem. That is, there could be reliable processes causing the belief that PRM is true.
Some might object that precisely the problem with a reliability theory is that its account of warrant runs plainly against some of our deepest intuitions about rationality, such as that beliefs are rational only if they held because of the reasons for them. But what is the worth of such intuitions when they are opposed by successful theory? But other intuitions seem to go the other way. If we hold that a belief is rational only if it is held because of reasons that we apprehend and duly consider, then this entails that most of our beliefs are irrational. Certainly all of our perceptual beliefs would be. I see a cup on my desk and immediately believe that there is a cup on my desk. Apprehending reasons has nothing to do with it. It would be highly counterintuitive to say that all of our perceptual beliefs are irrational. The same thing holds for many beliefs based on testimony. As soon as my wife tells me that it is raining again I immediately believe that it is raining again. I don’t weigh her credibility against my background beliefs or anything like that. I immediately, and rationally, accept it.
Perhaps Goetz and Taliafero mean only that theoretical knowledge is rational only if we get it by apprehending and a set of reasons and recognizing the sufficiency of their support for that theory. So, let’s cut to the chase and ask whether reasons would be epiphenomena on PRM, useless danglers that have no explanatory role in accounting for our beliefs? Not at all. In fact, it seems to me that to think that reasons would be epiphenomenal given PRM is to fail to take PRM seriously and to continue to think in dualistic terms.
Let’s begin by reviewing what it means to say that the mental is physically realized. PRM first defines the mind in functional terms; a mind is anything that does mental stuff. It then identifies the human brain (or, technically, certain physical subsystems of the brain) as the object that, for human beings, performs the function of doing mental stuff (including rational thought). At bottom, then, PRM is a theory about how we think; we do it with our brains. We have a mental system fully realized in our mental organ, the brain, just as we have a digestive system fully realized in the organs of digestion. The functioning of our mental system—those orderly, causally-linked patterns of neuronal firings—is how we think, just as the functioning of our digestive system—peristalsis, the secretion of digestive juices, etc.—is how we digest. Those neural processes in our brains are not a more fundamental reality to which thought can be reduced. They are thought itself—the genuine article. Further, the fact that we think with our brains does not make thought any less real, significant, or explanatory than it is on dualism.
Let’s imagine a case of simple inference by modus ponens: Upon arising in the morning I look out the window and see that the streets are wet. I infer that it rained overnight. Generally, that inference would be immediate, but I have not had my coffee yet, so my thinking process is slow. Let’s imagine that I think it out step by step: “I see that the streets are wet. I know that if the streets are wet, then it rained last night. Therefore, it rained last night.” According to PRM, what just happened here? What caused my belief that it rained last night? That belief, “it rained last night,” is neurally realized and, of course, its proximate cause was other neural events. However, those other neural events were events of a very special sort; they were also the thoughts “the streets are wet” and “if the streets are wet, then it rained last night.” So those physical events were also mental events—because the physical events are the doing of the mental events—and so an equally good explanation is that my belief was based on my reasoning validly in accordance with modus ponens.
Given PRM there are two ways of individuating a thought (speaking precisely we should say “a thought token,” but for simplicity I will just say “thought”). We could individuate it by indicating that a particular thought-content was entertained by a particular brain at a given time, e.g. “At time T1 Parsons thought ‘the streets are wet.’” Or we could individuate it by a specifying a particular set of neural events in a particular brain, e.g. “At time T1 this particular pattern of neuronal firing occurred in Parsons’ brain.” But just because we can individuate something in two different ways does not mean that we are individuating two different things. According to PRM, it is one and the same thought that is individuated in both ways. The neural event is the mental event. Thinking “If the streets are wet, then it rained last night; the streets are wet; therefore it rained last night” just is a causally connected series of neural events.
The upshot is that physical realization does not render the mental an epiphenomenon. On the contrary, it is the physical realization of the mental that “empowers” one mental event to cause another mental event. It is in virtue of their physical realization that mental events can cause other, physically realized, mental events. But doesn’t this mean that, as Goetz and Taliafero insist, it is the physical that does all the causing and the reasons are impotent? No, because, again, the physical causing of my belief and the being convinced by reasons are one and the same thing. The physical causing is the mental causing; that is what PRM means. In short, PRM holds that being convinced by reasons is something we accomplish with our brains.
I think that Goetz and Taliafero read PRM as a thesis of the one-way causation of the mental by the physical, rendering the mental into an epiphenomenon. But this is wrong. Melnyk is not saying that the physical produces the epiphenomenal mental like a car engine produces useless noise. It seems that Goetz and Taliafero misconstrue PRM because they continue to think in dualist terms. Dualism must regard the mental and the physical as two opposite and irreconcilable properties, whereas PRM erases that distinction and asserts that the mental is something that special physical things can do. If the thought that mental and physical as mutually exclusive categories is deeply entrenched for you, the claim of PRM will be hard to understand, much less accept.

bookmark_borderPlantinga’s Evolutionary Argument Against Naturalism refuted

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Here’s my central criticism of Plantinga’s Evolutionary Argument Against Naturalism (EAAN). It’s novel and was published in Analysis last year.
Here’s the gist. Plantinga argues that if naturalism and evolution are true, then semantic epiphenomenalism is very probably true – that’s to say, the content of our beliefs does not causally impinge on our behaviour. And if semantic properties such as having such-and-such content or being true cannot causally impinge on behaviour, then they cannot be selected for by unguided evolution. But this argument requires, crucially, that there be no conceptual links between belief content and behaviour of a sort that it’s actually very plausible to suppose exist (note that to suppose there are such conceptual links is not necessarily to suppose that content can be exhaustively captured in terms of behaviour or functional role, etc. in the way logical behaviourists or functionalists suppose). It turns out that if such conceptual links exist, then (rather surprisingly!) natural selection will favour true belief even if belief content is epiphenomenal. So, contrary to Plantinga, even if belief content has no causal impact on behaviour, natural selection can still select for true belief. The EAAN is therefore refuted. To resurrect the EAAN, Plantinga would need to show that there no conceptual links of the sort I envisage between content and behaviour, links of a sort that, as I say, do seem to exist.
NATURALISM, EVOLUTION AND TRUE BELIEF
Stephen Law
Plantinga’s evolutionary argument against naturalism (EAAN) is currently one of the most widely discussed arguments targeting philosophical naturalism (see, for example, Beilby 2002).  Plantinga aims to show that naturalism, in combination with evolutionary theory, is, as he puts it, ‘incoherent or self-defeating’. His argument turns crucially on the claim that, in the absence of any God-like being to guide the process, natural selection is unlikely to favour true belief. This, Plantinga supposes, is because natural selection selects only for adaptive behaviour. It is irrelevant, from the point of view of unguided evolution, whether the beliefs that happen to cause that adaptive behaviour are true.

I argue that, even in its most recent incarnation, the EAAN fails. In particular, Plantinga overlooks the fact that adherents of naturalism may hold, seemingly quite plausibly, that there exist certain conceptual links between belief content and behaviour. Given conceptual links of the sort I envisage, natural selection will indeed favour true belief.
I then point out a further interesting, and perhaps somewhat surprising, consequence of the existence of such conceptual links: that even if semantic properties such as being a true belief are epiphenomenal – even if such properties have no causal impact on behaviour – unguided evolution will still favour true belief.
The EAAN
For those unfamiliar with the EAAN, here is a brief outline.[1]Let Naturalism (N) be the view that there’s no such person as God or anything at all like God, and Evolution (E) be the view that our cognitive faculties have come to be by way of the processes postulated by contemporary evolutionary theory. Then, argues Plantinga, the combination N&E; is incoherent or self-defeating. This, he maintains, is because if N&E; is true, then the probability that R – that we have reliable cognitive faculties (that is to say, faculties that produce a preponderance of true over false beliefs in nearby possible worlds) – is low. But, concludes Plantinga, anyone who sees that P(R/N&E;) is low then has an undefeatable defeater both for R and for any belief produced by their cognitive faculties, including their belief that N&E;.
But why suppose P(R/N&E;) is low? Plantinga supports this premise by means of a further argument. He begins by asserting that
materialism or physicalism is de rigeur for naturalism… A belief, presuming there are such things, will be a physical structure of some sort, presumably a neurological structure. (Forthcoming: 2)
According to a proponent of naturalism, then, this structure will have both neurophysiological (NP) properties and semantic properties. However, it is, claims Plantinga, unlikely that the semantic properties of the neurological structure will have any causal effect on behaviour:
It is easy to see how beliefs thus considered can enter the causal chain leading to behavior; current science gives us a reasonably plausible account of the process whereby volleys of impulses propagated along the efferent nerves cause muscle contraction, motor output, and thus behavior. It is exceedingly difficult to see, however, how they can enter that chain by virtue of their content. A given belief, it seems, would have had the same causal impact on behavior if it had had the same NP properties, but different content. (Forthcoming: 2-3)
Plantinga concludes that N&E; makes semantic epiphenomenalism (SE) likely. But, says Plantinga, if semantic properties such as having such-and-such content or being true cannot causally impinge on behaviour, then they cannot be selected for by unguided evolution. Given SE, truth and falsehood will be, as Plantinga puts it, invisibleto natural selection. In which case, (on the modest assumptions that (i) 75% of beliefs produced must be true in order for a cognitive mechanism to be reliable and, (ii) that we have at least 100 such beliefs) P(R/N&E;&SE;) will be low.
So runs the EAAN. Recently, Plantinga has refined the argument by trying to tackle a certain sort of objection. The objection is that by also embracing, for example, reductive materialism (RM), adherents of naturalism may, after all, quite reasonably suppose that they have evolved reliable cognitive faculties. Why so? Well, on Plantinga’s understanding of RM, content properties just are NP properties. But then, because NP properties cause behaviour, and semantic properties just are NP properties, so semantic properties can cause behaviour. And if semantic properties can cause behaviour, then they can, after all, be selected for by unguided evolution.
Plantinga’s argument that P(R/N&E;&RM;) is low
In his most recent presentation of the EAAN, Plantinga attempts to deal with the above objection. He focuses his attention on one semantic property in particular – truth. Even supposing that semantic properties such as being true can causally affect behaviour, why, he asks, should we suppose, that unguided evolution favour beliefs that are true?
According to Plantinga, the combination N&E;&RM; gives us no reason to suppose that the content of belief/neural structures resulting in adaptive behaviour is likely to be true. Suppose the belief/neural structure resulting in a piece of adaptive behaviour has the content q. While the property of having q as content does now enter into the causal chain leading to that behaviour, it doesn’t matter whether q is true:
What matters is only that the NP property in question cause adaptive behaviour; whether the content it constitutes is also true is simply irrelevant. It can do its job of causing adaptive behaviour just as well if it is false as if it is true. It might be true, and it might be false; it doesn’t matter. (Forthcoming:10).
But if the NP property can do its job of causing adaptive behaviour just as well whether the content is true or false, true belief cannot be favoured by natural selection. In which case, concludes Plantinga, (PR/N&E;&RM;) remains low.
Conceptual constraints on likely semantic content
There is, it seems to me, a fatal flaw in even this latest incarnation of the EAAN.
Plantinga supposes that what unguided evolution favours, in the first instance, is adaptive behaviour. As to what causes that behaviour, evolution doesn’t care. True beliefs, false beliefs, something else – it’s all the same to evolution. It is only the result – adaptive behaviour – that is preferred.
But even if unguided evolution doesn’t care what causes adaptive behaviour, just so long as it is caused, it may not follow, given certain further facts about be
lief
that natural selection won’t also favour true belief.
Consider the suggestion that there exist certain conceptual constraints on what content a given belief can, or is likely to, have given its causal relationships to, among other things, behaviour. My claim is that, given the existence of certain conceptual constraints, unguided evolution will then tend to favour true belief.
To begin, let me sketch out a simple illustration of how such constraints might operate.  Suppose we just stipulatively introduce certain terms/concepts. Let’s say that a subject’s belief state has content MC1 iff that state has properties achieving a threshold of at least 30 points, with points allocated thus:
Property A     +20 points
Property B      +15 points.
Property C      +20 points
Property D     -12 points
Notice there’s no one property possession of which is essential if a state is to qualify as having the content MC1. Suppose we similarly stipulate that a subject’s belief state has content MC2iff that state possesses properties achieving a threshold of at least 30 points, with points allocated thus:
Property D     +20 points
Property E      +15 points
Property F      +20 points
Property A     -12 points
Note that if a subject has a belief state with properties A and B, then, ceteris paribus, that state is rather more likely to have the content MC1 than it is the content MC2 (though it might yet turn out to lack content MC1 and possess content MC2 instead if it also possesses properties D, E and F while lacking C). Now suppose that while not all these properties involve causal links to behaviour, some do, namely A, C, D and F. Property A is that of causing behaviour B1 in situation S1, C that of causing behaviour B2 in situation S2, D that of causing behaviour B3 in situation S3, and F that of causing behaviour B4 in situation S4.
Having introduced these conceptual constraints on what it is to have beliefs with the contents MC1 and MC2, we can now see how natural selection might select not only for or against certain behaviours in certain situations, but also for or against these two belief contents. Suppose that exhibiting B1 in S1 and B2 in S2 is in each case adaptive, while exhibiting B3 in S3 or B4 in S4 is maladaptive. Then, other things being equal, natural selection will tend to favour subjects holding beliefs with content BC1 over those holding beliefs with content BC2. So, given conceptual constraints on belief content of the sort outlined above, natural selection need not be blind to belief content. It will select for some contents over others, depending on the kinds of behavioural output with which they are conceptually associated.
So now suppose that constraints of this sort exist on the content of beliefs of the sort with which we are already familiar – contents such as that there is water five miles south, that Paris is the capital of France, and so on. Suppose these constraints conceptually link content with behavioural output. No doubt these constraints will be more complex than in my illustration. But, supposing they exist, with what sort of behaviour is a given content likely to be conceptually linked?
Suppose that, solely in combination with a very strong desire for water, a certain belief/neural structure typically results in a subject walking five miles to the south. Surely, if there are such conceptual links between behaviour and content, then the property of causing that behaviour in that situation will be among those properties lending, as it were, a considerable number of points towards that belief/neural structure achieving the threshold for having the content that there’s water five miles south. Other things being equal, that belief/neural structure is much more likely to have the content that there’s water five miles south than it is, say, the content that there’s isn’t water five miles south, or that there’s water five miles north, or that there’s a mountain of dung five miles south, or that Paris is the capital of Bolivia. Perhaps the belief/neural structure in question might yet turn out to have one of these other contents. We can know a priori, solely on the basis of conceptual reflection, that, ceteris paribus, the fact that a belief/neural structure causes that behaviour in that situation significantly raises the probability that it has the content there’s water five miles south. Among the various candidates for being the semantic content of the belief/neural structure in question, the content that there’s water five miles south will rank fairly high on the list.
But now notice that, given such conceptual constraints exist, unguided evolution will indeed favour true belief. Consider our thirsty human. He has a strong desire for water. He’ll survive only if he walks five miles south to where the only reachable water is located. He does so and survives. Suppose this adaptive behaviour is caused by a certain belief/neural structure. If there are conceptual constraints on belief content of the sort I envisage, and if a belief/neural structure in that situation typically causes subjects to walk five miles south, then it is quite likely to have the content that there’s water five miles south – a true belief. Were our thirsty human to head off north, on the other hand, as a result of his having a belief/neural structure that, in that situation, typically causes subjects to walk five miles north, then it’s rather more likely that the belief in question is that there’s water five miles north. That’s a false belief. Because it is false, our human will die.
So if beliefs/neural structures cause behaviour,
and if there are conceptual constraints linking content with behavioural output of the sort I am suggesting, then natural selection won’t just favour adaptive behaviour. It will also favour true belief.
True, there are other candidates for being the content of the belief that causes our human to head off in the right direction. Perhaps some are more likely candidates. Suppose our human has no conception of miles or south. Then, instead of the belief that causes his behaviour having the content that there’s water five miles south being, perhaps it has instead the content that there’s reachable water thataway. However, notice that, either way, the content of the belief in question is still true.
To sum up: what Plantinga overlooks, it seems to me, is the possibility that there exist conceptual constraints on content of the sort outlined here. The suggestion is that if beliefs are neural structures, then it is at least partly by virtue of its having certain sorts of behavioural consequence that a given neural structure will have the content it does. If such constraints exist, then one cannot, as it were, plug any old belief content into any old neural structure, irrespective of that structure’s behavioural output. We run up against certain conceptual obstacles. If such conceptual constraints exist, it appears natural selection will favour not only adaptive behaviour, but also true belief.
Neither materialism nor functionalism not presupposed
Note that to suggest that such conceptual constraints on belief content exist is not, of course, to presuppose that beliefs are neural structures or that materialism is true. Let’s suppose, for the sake of argument, that substance dualism is true and that beliefs are not neural structures, but soul-stuff structures. Then my suggestion is that we may be able to know on the basis of a little conceptual reflection that if beliefs are soul-stuff structures, and if a given soul-stuff structure in combination with a strong desire for water typically results in subjects walking five miles south, then ceteris paribus that soul-stuff structure is quite likely to have the content that there’s water five miles south, and is rather unlikely to have the content that there’s water five miles north.
Also note that to suggest that there exist conceptual constraints on content given behavioural output is not to presuppose the truth of some reductionist, materialist-friendly theory of content of the sort that Plantinga has gone on to attack[2], such as Dretskian indicator semantics or functionalism. Perhaps belief contents cannot be exhaustively characterized in terms of their causal connections to input and output, as some functionalists claim. That’s not to say that there are no conceptual constraints at all on what the content of a given belief is likely to be, given the causal links that belief has to behaviour. Perhaps there are. Consider my illustration involving contents MC1 and MC2. I stipulated that not all of the weighted properties involved causal connections with behavioural output. Properties B and E involved no such connections. Indeed, B and E might even be properties presenting an insurmountable obstacle to any attempt to characterize the content of MC1 and MC2 in wholly functionalist terms. It wouldn’t follow that there are no conceptual constraints at all on beliefs having content MC1 and MC2 given their behavioural output. Clearly there are.
So, while the combination N&E;&RM; might be self-defeating, it seems that the addition of CC – the thought that there are conceptual constraints on content of the sort I envisage – produces a combination of beliefs that is not, after all, self-defeating. It appears there are ways of embracing naturalism that sidestep Plantinga’s charge of incoherence.
How natural selection can still favour true belief even if SE is true
In fact, it turns out that in order to sidestep Plantinga’s charge of incoherence our naturalist doesn’t even have to sign up to RM. The addition of CC to R&E; aloneis sufficient to rescue naturalism from self-defeat, as I’ll now explain.
As we saw above, Plantinga’s initial worry about naturalism is that it makes semantic epiphenomenalism (SE) likely. He supposes the naturalist will hold that beliefs will be neural structures possessing both neurophysiological (NP) properties and semantic properties. However, Plantinga thinks that only the NP properties of those structures will then have any causal effect behaviour. A given belief would have the same causal impact on behaviour if it had the same NP properties but different semantic properties (or indeed no semantic properties at all).
So now let’s suppose our naturalist actually bites the bullet and accepts SE – they actually accept that the semantic properties of a given neurological structure have no causal impact on behaviour. Plantinga supposes such a naturalist is then compelled to accept that, because natural selection can only select for adaptive behaviour and the properties that cause it, so natural selection cannot select for the semantic property of being true. However, it turns out that Plantinga’s assumption that natural selection favours only adaptive behaviour and the properties that cause it is unwarranted. It turns out, somewhat surprisingly, that, given CC, natural selection will still favour true belief even if the property of being a true belief has no causal impact on behaviour.
To see why, let’s return again to our thirsty human. He has a certain belief/neural structure that, in conjunction his strong desire for water, causes him to walk five miles south. Given the kind of conceptual constraints outlined above, a belief/neural structure that causes a subject to walk five miles south given a strong desire for water will quite probably have the content there’s water five miles south. Notice it really doesn’t matter whether or not that belief/neural structure causes that behaviour by virtue of its having that semantic property. It remains the case that, if that sort of neural structure for whatever reason has that behavioural consequence, then, given CC, it quite probably has the conten
t there’s water five miles south and probably doesn’t have the conceptual content there’s water five miles north. It matters not whether SE is true: the behavioural output of a belief/neural structure still places constraints on its likely content.
But then, given such conceptual constraints, natural selection is likely to favour true belief even if SE is true. Odd though it might seem, given CC, natural selection will favour true belief even if the property of being a true belief has no causal impact on behaviour. This is a rather significant discovery, even setting aside its relevance to Plantinga’s EAAN.
Conclusion
Of course, I am merely making a suggestion. Perhaps there exist no such conceptual constraints on belief content of the sort I envisage. Still, the view that there are such constraints on content is widespread (it is by no means restricted to those wedded to some form of logical behaviourism or functionalism, for example). It seems intuitively obvious to many of us that belief content is not entirely conceptually independent of behavioural output: that one cannot plug any old belief content into any old neural structure (or soul-stuff structure, or whatever) entirely independently of its behavioural output. That intuition would appear to be, philosophically speaking, largely pre-theoretical. It cannot easily be dismissed by Plantinga as a product of some prior theoretical bias towards naturalism and/or materialism.
My central conclusion, then, is this. Plantinga has not shown that naturalism in combination with the theory of evolution is unavoidably self-defeating. It appears that an adherent of N&E; who also supposes CC is true can, after all, quite reasonably suppose they have evolved reliable cognitive faculties.
In response, Plantinga might now try to show that if naturalism is true, there are unlikely to be conceptual constraints on semantic content of the sort I describe. Perhaps he can do this. If so, then the EAAN might be resurrected. But as things stand, it is not naturalism that is defeated, but the EAAN.[3]
Heythrop College, University of London
London W8 5HN
References
Beilby, J. (ed) 2002. Naturalism Defeated? Essays on Plantinga’s Evolutionary Argument Against Naturalism. Ithaca: Cornell University Press.
Plantinga, A. Forthcoming. Content and Natural Selection. Philosophy and Phenomenological Research. Currently available on-line at Plantinga’s departmental webpage: http://philosophy.nd.edu/people/all/profiles/plantinga-alvin/documents/CONTENTANDNATURALSELECTION.pdf
Page numbers refer to the on-line version.


[1] I here follow the most recent version of the EAAN as presented in Plantinga (Forthcoming).
[2] See the latter part of Plantinga (Forthcoming).
[3] My thanks to Alvin Plantinga for his generous comments on earlier drafts.