No Competition for Naturalism:
Naturalism itself challenges the commonsense dualisms that the Christian tradition has helped to reinforce: body vs. soul, mental vs. physical, free will vs. fate, and the natural vs. god and the supernatural. But beyond upsetting commonsense (not a reliable guide to reality in any case), naturalism seems poised to visit a host of horribles upon us, among them reductionism, determinism, mechanism, atheism and nihilism. Not a pretty picture, so in attacking naturalism G&T are primarily concerned to defend the plausibility of dualism, especially mind-body dualism, which in turn will secure the reality of the soul, consciousness, libertarian free will, and, ultimately, god. The truth of theism will protect us from the apparently demoralizing consequences of holding a naturalistic worldview.
They dig into some of the more problematic areas of scientific naturalism, occasionally to good effect, pointing out well-known difficulties in naturalizing such things as consciousness, morality and rationality. In so doing, they hope to increase the plausibility of their anti-naturalist, dualistic alternatives. But whatever the shortcomings of naturalistic explanations (naturalists candidly admit we don’t have it all figured out), their dualist explanations are in much worse shape, perhaps necessarily so. A root divide in one’s ontology, after all, presents formidable barriers in explaining how two categorically different sorts of things (soul and body, the natural and the supernatural) interact, as we’ll see below. The perennial difficulty with dualism, including traditional theism, is that no transparent explanations seem forthcoming about such interaction. Moreover, such explanations, if successful, would inevitably work to unify our understanding of what exists, showing how things are of a single world, whatever their diverse characteristics. But this is the naturalist’s project!  Anti-naturalists, committed to the existence of something beyond nature, are perhaps logically barred from showing us clearly how the world, split in two, works. The very idea of a cogent, transparent supernaturalistic explanation of a phenomenon seems self-contradictory.
G&T begin by drawing a distinction between what they call strict and broad naturalism. Strict naturalism follows the physical sciences in specifying what ultimately exists, and so is aggressively materialist and reductionistic. It is thus eliminativist in denying the existence of what are ordinarily thought to be categorically mental or non-physical things, in particular consciousness and the soul. Broad naturalism, on the other hand, is more liberal, non-reductionist, and pluralistic in accepting the ontologies of the non-physical sciences (e.g., psychology and history), and thus it accepts the prima facie reality of mental phenomena. But both varieties share what G&T say is the primary characteristic of naturalism: the denial of the supernatural as a distinct ontological realm (and therefore the denial of supernatural souls and gods), and more generally a monistic, as opposed to dualistic conception of ourselves and reality overall.
The strict/broad distinction usefully picks out different brands of naturalistic theories about the mind and the world (and of course there’s lots of intermediate ground), but the basic cognitive commitment of naturalism is the same: to achieve a transparent explanation of phenomena and follow it wherever it leads, even if this comes at the cost of denying what seems natural, commonsensical and reassuring. So it isn’t as if G&T have detected a root schism within the naturalist community – nasty reductionists vs. nice anti-reductionists. Even though intuitions about the nature of mind and reality vary greatly, everyone has the same end in view and subscribes to basically the same empirical methods of investigation and standards of proof. Everyone accepts the possibility that they could be wrong, and especially when it comes to the nature of consciousness and mental phenomena generally, no naturalist supposes the question is anywhere near settled. The empirical, open-ended, fallibilistic approach to investigating the world, in service to transparent explanation, is what unites naturalists and most distinguishes them from anti-naturalists, including G&T and other theists, who respect very different, often non-empirical standards when deciding questions about ultimate reality. It’s unfortunate that the methodological and epistemic commitments of naturalism, as contrasted with those of anti-naturalism, don’t get more attention in this book, since it’s these commitments that largely determine where these very different worldviews end up. 
Still, these commitments come into play as G&T examine the “strict” naturalist case for the causal closure of the natural world, the thesis that “a scientific examination of bodily action leaves no explanatory room for anything non-physical” (p. 28). If causal closure is true, this means that there’s no role for the immaterial soul and its freely willed, undetermined choices in explaining behavior – there’s no libertarian free will. It also entails that there is no such thing as mental-to-physical causation, so consciousness must therefore be epiphenomenal, should it turn out to be something other than the neural processes correlated with it. (If it’s the same thing, then it inherits all the causal powers of the neural processes, so isn’t epiphenomenal.)
But, say G&T, it’s implausible to suppose that, for instance, our goal-oriented, conscious intentions don’t play a role in behavior; we simply can’t explain our bodily doings without appealing to teleological – that is, purposeful, reasons-based – choices. This means that “…ultimately in order to explain adequately (teleologically) the movement of our limbs, there must be causal openness in our brains,” an openness which permits mental-to-physical causation (p. 30, original emphasis).
This argument assumes that reasons and purposeful behavior can’t possibly be materially instantiated, that they can’t find a sufficient substrate in neural mechanisms. G&T say “The most serious problem [for the reductionist argument for causal closure] is that the mental and physical appear to be irreducibly distinct” (p. 32). Indeed, the conscious experience of having purposes and reasons, or making choices, or any phenomenal content of consciousness for that matter (feeling pain, seeing red) might appear at first blush to be something quite other than the operation of neural processes. But sticking with commonsensical appearances as guides to reality is a methodological non-starter if we’re trying to get to the bottom of things. Why suppose that the apparent distinctness of the mental and physical necessarily reveals anything fundamental about their true nature?
In a similar vein, G&T say that “a …dualist’s reason for thinking that a soul is located in the space occupied by its physical body is simply the fact that that is where it seems to be located” (p. 65, emphasis added). But again, why take such seemings as dispositive about the facts of the matter? From the scientific naturalist’s perspective, the evidential weight G&T put on unreconstructed folk metaphysics of the mind and soul, based on how things immediately appear to us, is unwarranted. There might be a categorically separate immaterial realm, but to have confidence in this claim we have to look beyond and beneath appearances to establish it as part of a transparent, evidence-based picture of how reality works. 
G&T make much of what’s known in the philosophy of mind as the explanatory gap: there’s no obvious, canonical way (yet) to show how qualitative, phenomenal experience – the feeling of pain, for instance – could be identical to, or in some sense entailed by, neural processes. But the existence of this gap doesn’t mean that neural processes can’t, when viewed as representational processes, instantiate reasons and intentions by encoding information about our internal goal-directed states and the world external to us. There can be both a physical, neural level description of what the brain does and a corresponding informational, higher-level description in terms of physically-realized representational states, neither of which conflicts with the other. This is the case even if there’s a mystery about how neural processes might entail qualitative consciousness. This means that we need not assume the existence of a separate, immaterial mental realm to explain the teleological character of our choices, in which case there’s no problem with causal closure at least on this score: the physical brain can, all by itself, instantiate reasons. And for this very reason reasons themselves can be a category of physically instantiated causes, not exceptions to natural cause and effect. There needn’t be a mysterious, contra-causal, libertarian free will, operated by a non-physical soul for our choice-making capacities to guide goal-directed (hence teleological) behavior. 
But let’s suppose, playing along with dualism, that there is a categorically mental, non-physical realm, one which includes the immaterial soul and its will. How would the required mental-to-physical causation work, such that, for instance “the micro-physical neural impulses that led to…finger movements must ultimately have originated with the mental activity of a soul that was choosing to act for a purpose” (p. 37)? This is where G&T have absolutely nothing to offer those looking for transparent explanations of behavior, human or divine. The closest they come to a positive statement of mental-to-physical causation is this rhetorical question: “Why could not an actualization of a neural capacity…be caused by an exercising of a mental power (a mental event) alone which is made for a purpose?” (p. 41). Well, perhaps it could, but one would like an account of how this mental power works in actualizing a neural capacity. Adverting to the mere possibility of mental causation hardly establishes its plausibility, whether for the soul or for god.
They say ruling out mental causation would beg the question about causal closure, but causal closure is simply what philosopher Owen Flanagan calls a justifiable regulative assumption in the mind sciences.  In the (notable) absence of any explanation of how mental events cause physical events, it’s the default working hypothesis that now drives scientific progress in understanding the mind. By contrast, the dualist assumption that mental events cause physical events hasn’t been productive because no researchable mechanism of their interaction has ever been proposed. It may be “natural” and commonsensical to suppose such interaction occurs, but there is thus far no scientific basis to suppose it does.
Although they try at length to explain how an immaterial soul could interact with a human body in making free, undetermined choices (with the help of what they call a “non-causal pairing relation”), G&T nevertheless cannot enlighten us on the mystery of mental-to-physical causation:
Similarly they write:
What’s striking is that G&T don’t see this lacuna in
their dualistic account of mind as being particularly problematic, whereas for a
naturalist the best (and perhaps only) reason to believe in dualism, mental
causation and libertarian free will would be if we had a clear, evidence-based
picture (or even a plausible preliminary sketch) of the causal relations between
soul and body. Absent that, soul-body dualism, however natural a view of human
nature it might be, has little going for it, either as a specific, testable
explanatory hypothesis or as a regulative assumption in the mind sciences. It’s
true that if one is committed to dualism on other grounds, then the
mysterious nature of mental causation might not present much of an obstacle. But
since naturalists place a high premium on explanatory transparency as grounds
for belief, such a mystery disqualifies dualism as a serious naturalistic
proposal. This is especially the case since non-dualistic accounts of the
self, consciousness, choice, rationality and other higher level human
characteristics and capacities are making substantial headway, even if they are
in their infancy.
Indeed, their main complaint against naturalists is that we put all, or at least most, of our explanatory eggs in the scientific basket, not recognizing the limits of science and the resources of other non-scientific modes of knowing. An effective attack on the plausibility of naturalism would therefore require that they elucidate and defend these other modes as reliable guides to reality. But just as they offer no clear non-naturalistic account of how the soul controls the body, they offer no clear extra-scientific grounds for dualism or, most critically, for theism (a special case of dualism). The gaps in naturalistic explanations that G&T make so much of would seem to give them ample opportunities to propose convincing supernaturalistic explanations, but these are sketchy at best.
For instance, in criticizing Daniel Dennett’s demand for a bottom-up explanation for consciousness, they ask:
Well, why should we? The shortcomings of scientific naturalism don’t count as a good reason to consider a theistic worldview unless it has something positive going for it as a non-scientific, supernatural explanation, something beyond the all too obvious fact that it fulfills our every wish and dream for a beneficent universe. What might this be? At one point G&T offer something akin to a Staples “easy button” explanation of consciousness and values, phenomena that they’ve said all along pose the very toughest explanatory enigmas:
That was easy! By positing the existence of divine nature, we get consciousness and values for free as part and parcel of created reality. With such quick and simple strokes do theists dispose of our knottiest explanatory problems. Of course, inquiring minds will want a bit more in the way of background information: where, exactly, did the deity come from? Does the existence of god – a patently unexplained explainer – reduce mystery, which is what explanations are supposed to do, or rather increase it?
G&T say that naturalists don’t give dualism and theism a fair hearing: “If naturalists were to give credence to libertarian freedom and teleological explanations on the plane of humanity, perhaps they would begin to reassess more constructively intentional, teleological explanations on the plane of the divine” (p. 94). But the naturalist, or anyone for that matter, needs some good, positive reasons beyond the shortcomings of science and appeals to the “natural” view of human nature to give credence to libertarian freedom and supernatural teleological explanations (we’ve seen above that teleological explanations can be naturalistic). That such reasons are largely lacking in a book intended to undermine naturalism suggests they’re not particularly obvious.
In the final chapter, in which they defend theism against what they admit are “powerful arguments” coming from naturalism (p. 98), G&T offer a number of rather underwhelming rejoinders. In justifying theism they write:
The weakness of this conclusion is not just that it’s stated in the negative, but that G&T equate positing divine agency with an evidence-based, theoretically well-motivated posit (of the existence of charge or spin), as if there were the least resemblance. This is simply to ape science without doing its observational and theoretical work, which only points up the emptiness of theistic explanations. Other sallies in defense of theism are equally tepid, essentially just affirmations of its bare possibility:
Well, science doesn’t rule out alternative non-naturalistic metaphysics, it’s just that one would like a positive non-scientific account of such a thing. This would help to disqualify naturalism, or at least give it some competition, but the account isn’t forthcoming. Similarly, and rather shockingly, they say:
If G&T don’t need the plausibility of dualism to ground their worldview, then we’ve arrived at a basic difference between them and most naturalists, namely the epistemic demands to which each side holds itself responsible. Although dualism might be conceptually coherent, the naturalist requires a good deal more before signing on to a worldview, namely its robust confirmation by our best, most reliable way of knowing – science. Mere coherence, without the additional requirements of intersubjective evidence and theoretical justification, makes us the all too easy marks for wishful thinking, subjective bias, and the influence of received wisdom about what’s “natural.”
In offering their critique of naturalism, G&T hope to undo it, but instead they’ve highlighted the explanatory poverty of dualism and theism. Where the naturalist seeks a clear causal story about the mind and the universe, they point to the soul, to libertarian free will and god as unmoved movers, necessarily mysterious in their workings. Where the naturalist wants good evidence and theory to back up claims to knowledge, they are content with the questionable deliverances of commonsense and subjective appearances. Where the naturalist admits that our understanding is at least temporarily at a loss, for instance in grasping the nature of consciousness, they short-circuit the investigation by invoking divine nature as the cause of it all. There is no convincing supernatural story here, indeed no story at all, only gestures in the direction of god.
They will of course not agree with this assessment. Instead, they find naturalism deficient in failing to confirm a “natural” view of mind and self, and in failing to provide any explanation for the totality of existence. For them, the theistic hypothesis neatly solves both problems and has sufficient non-scientific, philosophical warrant in the bare possibility of dualism. Besides, dualism and theism have the great psychological advantage of reassuring us that the world is as we naturally see it, and that it’s basically to our liking: overseen by an all-good god who has the best for us in mind, eventually. Naturalism clearly loses in the don’t rock the boat and wish-fulfillment departments.
But those deciding between naturalism and anti-naturalism, specifically G&T’s brand of theism, can consider the following: which worldview is more open about its shortcomings, which is more rigorous in its epistemic defenses against wishful thinking and therefore more likely to be true, and which provides, as a result, the clearest, most observationally and theoretically plausible account of the world and ourselves? If your primary goal in choosing a worldview is reassurance, theism is the way to go. But if you think a worldview should reflect the way the world objectively is, not your hopes or fears, then science-based naturalism is the obvious choice.
TWC, July 2008
here for a response to this review from Goetz & Taliaferro and a rejoinder
 I undertake a systematic examination of these differences in commentary on a debate between G&T and Andrew Melnyk here, and in reviews of John F. Haught’s books God and the New Atheism and Is Nature Enough?.
 “That the mind is the brain is thus a regulative assumption that guides contemporary mind science…” p. 78, The Problem of the Soul.