Most of the greatest theologians have not only been conversant with the philosophical movements current in their time (e.g. Neoplatonism, Aristotelianism), but have been highly articulate expositors and critics of them. However, most theologians today appear singularly uninterested in, if not wholly oblivious to, the reigning philosophical paradigm of naturalism. That is not to say naturalism is not affecting theology, for indeed it is. The work of naturalists like W.V. Quine, Wilfred Sellars and Richard Rorty has had a deep impact on contemporary theology. Every time a theologian argues that the correspondence theory of truth, a priori knowledge, or metaphysical realism is to be rejected, and every time it is argued that the only way to provide an epistemic justification of theologian enquiry is to model it on scientific enquiry, one can expect that arguments originating in a naturalist worldview are nearby. But should it not cause us concern that naturalism, as Sellars summarizes it, is the view that “science is the measure of all things, of what is that it is, and of what is not that it is not”? I would suggest that we need an in-depth reflection both on the impact of naturalism on theology, and more basically on naturalism itself as a philosophy. Fortunately this latter task has already been taken up in Naturalism: A Critical Analysis, a rigorous and challenging collection of essays by a number of leading philosophers.
In the preface, the editors William Lane Craig and J.P. Moreland define naturalism as including the following beliefs: the spatiotemporal universe of scientific study is all there is, first philosophy is to be rejected, and the universe is a causal continuum that is explained by the atomic theory of matter and evolutionary biology. Craig and Moreland summarize the price that must be paid for this view with the following dilemma which re-emerges in a number of the essays:
[E]ither naturalism involves an epistemic attitude and etiology that express strong versions of scientism, in which case naturalism suffers from some obvious defects (no account of proper functioning, denial of consciousness) or else it must weaken its ontology to adopt certain entities (abstract objects, mental properties), in which case it loses the unity of science and its right to claim a strong naturalist epistemic attitude, explanatory hegemony, and an adequate etiological account of the coming-to-be of everything. (p. xiv)
Put another way, the cost of consistent naturalism is implausibility, whereas a more plausible naturalism (one able to accommodate consciousness, intentionality, moral obligation, proper function, etc.) must surrender consistency by admitting non-material ontological realities.
The book is divided into four parts: epistemology, ontology, value theory, and natural theology. The first three essays effectively demonstrate the epistemological impoverishment of naturalism.
In “Farewell to Philosophical Naturalism,” Paul Moser and David Yandell point out that ontological naturalism entails that only material objects exist; the problem is that this is a global claim which cannot be warranted on scientific grounds, which, on this view, are the only grounds on which one may make knowledge claims. This places the naturalist in the dilemma of espousing a criterion for knowledge which he does not himself meet. This renders the naturalist thesis unjustified and perhaps self-refuting.
In “The Incompatibility of Naturalism and Scientific Realism,” Robert Koons takes up the epistemological inadequacy of naturalism in grounding realism. Koons points that the while scientists depend on simplicity as a guide for theory choice, naturalism can offer no grounds to think simplicity is reliable for producing true beliefs, and so no ground to view science as providing knowledge. The ironic conclusion is that the more successful science is, the more evidence it provides against naturalism.
Dallas Willard’s essay “Knowledge and Naturalism” turns away from the narrower issue of how naturalism relates to science to focus on the broader epistemic implications of this austere worldview. Willard argues that having knowledge is an objective state in which a subject matter is appropriately represented as it is; that is, knowledge requires a representation which matches up to the world under the correct conditions (e.g. not by chance). Since naturalism only allows for the existence of physical properties and relations, it can account neither for matching representations nor for truth or knowledge. Since we clearly have knowledge, it follows that naturalism is false.
The section on ontology begins with J.P. Moreland’s essay “Naturalism and the Ontological Status of Properties.” Properties represent a prime case of an ontological reality which must be eliminated or conformed to a naturalist worldview, a fact which has been recognized by naturalists since the time of Plato (Sophist, 246 A-C). Moreland critiques two attempts to reconcile naturalism with properties: Keith Campbell’s reductive nominalism and David Armstrong’s revised realism. Moreland points out a host of difficulties with each proposal while observing that in an attempt to respond to criticism, Campbell and Armstrong come close to a traditional realist reading of properties which would undermine naturalism.
While naturalism offers no plausible account of properties, in “Naturalism and Material Objects” Michael Rea argues that it cannot even provide a ground to accept the existence of material objects. This claim is rooted in the thesis that the identification of material objects requires us to identify “persistence conditions” for those objects. To take one of Rea’s examples, if Socrates is a material object, there must be some fact about whether Socrates could survive a trip through a meat grinder. While the non-naturalist can provide an a priori account of the knowledge of persistence conditions, the naturalist can only appeal to natural laws or proper function, both of which fail. And so naturalism provides no warrant to accept the existence of material objects.
Charles Taliaferro’s essay, “Naturalism and the Mind,” attacks eliminative and reductive treatments of the mind/body problem. Eliminativism dismisses the mind as a “user illusion,” but this begs the question of what the “user” is. Identity theory, which claims that the mind is a set of brain states, is undermined by the fact that the mind bears properties not possessed by the brain. More recently, a number of philosophers of mind have retreated to the claim that mental properties are distinct entities which “supervene” on the physical, but this places the naturalist in the dilemma of introducing immaterial objects into a naturalist ontology. While naturalists will continue to protest that body/soul dualism is too extravagant, Taliaferro counters that such judgments are made relative to one’s worldview. Immaterial minds are much more plausible if we accept theism which sees all material reality as arising from God, the ultimate “immaterial mind”. At the close of the essay Taliaferro provides a brief but helpful discussion of body/soul integration for those theologians and philosophers who fear that dualism irrevocably sunders the person.
Stuart Goetz’s essay “Naturalism and Libertarian Agency” is a fitting complement to Taliaferro’s. Goetz points out that naturalists cannot accept intentionality — the irreducible aboutness of one’s thoughts — and thus can only explain actions in terms of prior efficient causes. Goetz contends rather that actions are uncaused, and as such are explained not causally but teleologically, that is in terms of the intended end of the agent. (I move my arm because I want to pick up the chocolate bar, not simply because of prior neuronal synapses.) A number of other naturalists have objected that libertarianism requires a “self” (the soul by another name) which is the seat of the deep intentional features of the world and is able to act in the causal order. This raises the main objection naturalists invoke against dualism, the problem of mind/body interaction. Given the inadequacies with eliminativism and identity theory, a number of naturalists have recently defended the supervenience thesis that mental properties arise out of, and are determined by, physical properties. However, as Goetz points out, supervenience theories face basically the same objection as dualists since they fail to explain the deterministic relation between microphysical properties and supervenient mental properties. What is more, this view is grossly implausible, as it treats consciousness as epiphenomenal, arising out of but incapable of effecting the material realm. Since we clearly do act on the basis of intentions rather than simply as a result of physical causes, we should accept libertarian freedom and the body/soul dualism it implies.
The section on value theory is comprised of John Hare’s essay “Naturalism and Morality”. Hare argues along Kantian lines that there is a gap which arises when we recognize that there is a moral demand placed upon our lives, and that we are naturally incapable of meeting it. The gap depends on the famous principle of “ought implies can” which has received short shrift from some theologians who stress the human incapacity to do good; but as Hare points out, for the Christian theist the “can” only arises because of divine grace. Hence, if we are required to meet a moral gap, it follows that with God’s grace we are able to do so. Hare critiques naturalist attempts to eliminate the gap by claiming the demand can be met, or by invoking another principle (usually evolutionary biology) to traverse it. Since each naturalist attempt to traverse the gap fails, naturalism leads to the moral incoherence of positing moral obligations we cannot meet. The only way to meet the gap and restore coherence is by recognizing the divine source of morality and God’s granting us the power to meet it.
The final section on natural theology begins with William Lane Craig’s essay “Naturalism and Cosmology,” which provides a comprehensive survey of the challenges Big Bang cosmology presents to naturalism. Naturalists have always tended to answer the vexing question, “Why is there something rather than nothing?” by appealing to the universe as an eternally existent brute fact. However, with the rise of Big Bang theory which points to the entire space-time universe arising out of nothing a finite time ago, that escape route is no longer open. To avoid what smacks of special creation, naturalists have appealed to a growing list of ever more incredible and empirically unfounded theories of cosmic origin, including steady state theory, oscillating universes, and quantum fluctuations. Recently, some philosophers and cosmologists have even claimed the universe creates itself, while others have suggested that it arose uncaused from nothing at all. Craig takes apart each of these would-be theories while defending the axiom that whatever begins to exist has a cause. Since the universe began to exist, this would require (so Craig then argues) an uncaused personal creator who, apart from the universe, is without beginning or change and is immaterial, timeless, spaceless, and of great power. Craig concludes, “And this, as Thomas Aquinas laconically remarked, is what everyone means by ‘God’.” (p. 244)
In the final essay, “Naturalism and Design,” William Dembski argues that the current scientific explanatory criteria of chance and necessity are inadequate; we must also invoke the concept of intelligent design. And this provides the basis for an impressive new teleological argument. Many philosophers still dismiss teleological arguments with a nod to Hume. But Dembski argues that we may now appeal to the rigorous criteria of complexity and specification, culled from their pervasive pretheoretical use in numerous disciplines, to guide intelligent design theory. A design inference is warranted if an intelligible pattern is of sufficient complexity to preclude chance, and if it bears a precise specification or pattern. An excellent example is provided by Michael Behe’s “irreducibly complex” systems in biochemistry. These are biological objects and operations which depend for their function on a number of parts being in working order. Since the complexity of these systems precludes the possibility of their arising by chance, and they bear a precise specification, a design inference is warranted. Dembski adds that intelligent design will not quash scientific enquiry, but rather may guide the development of new research paradigms by eliminating false premises and focusing the goals of enquiry.
It is often the case that collections of essays by different writers lack an overall cohesion, but not so for Naturalism: A Critical Analysis. These essays are mutually reinforcing as the authors build a cumulative case against naturalism. While this is a mark of good editing, I must take issue with Craig and Moreland’s editorial decision not to present a set of definitions on naturalism and its various cognates at the outset. As it stands, there are a bewildering number of naturalisms thrown at the reader through the course of the essays (e.g. metaphysical, epistemological, methodological); as such, a standardized set of terms observed through all the essays would have been very helpful. It must also be noted that while one cannot cover every pertinent issue in a book such as this, certain omissions are more noticeable (and regrettable) than others. Given the growing number of naturalist philosophers presently reconsidering a priori knowledge, an essay dedicated to the centrality and anti-naturalist nature of aprioricity would have been timely. Further, an essay on the fine-tuning for the universe would have been a valuable complement to Craig’s essay. But perhaps most unfortunate is the sparse treatment of value theory, particularly the lack of any sustained discussion of metaethics.
Granted Naturalism: A Critical Analysis is an important work, but is it important enough to command the attention of a busy theologian already spread too thin over systematic theology and related disciplines? While many may dismiss this book as too recondite, with a little reflection one can see room to raise important theological questions at almost every turn. For instance, if properties exist apart from their exemplification in concrete objects then what are they? Divine thoughts? Should Calvinists find concord with the compatibilist arguments of naturalist philosophers, or is libertarianism, as Goetz defines it, the only proper Christian view of the person? Is t=0 (the point of the Big Bang) of theological significance, as Craig assumes, and if so, how?
The book also provides a significant challenge to the influence that naturalism has already had on theology. Take the example of body/soul dualism. It is well known that the soul has receded in discussions of theological anthropology in recent decades. Indeed, it has often been rejected on what are alleged to be strong biblical and theological grounds. But ever since Gilbert Ryle derided “the ghost in the machine”, many of those reasons have also been philosophical and “scientific”, and these are commonly rooted in naturalist presuppositions. There is a good deal of confusion here as theologians juxtapose “dualism” with “holism” as if they were contraries, when in fact the two may be fully complementary. In rejecting the soul, these theologians are embracing physicalism, not holism. (And this is certainly no less a contentious thesis on biblical grounds than is dualism.) Now most anti-dualist theologians would be unhappy with the physicalist description of human beings as computers made of meat. But if they reject eliminativism and identity theory (and given the reasons put forth by Taliaferro and Goetz, they should) then they are left with a form of supervenience. But supervenience is best understood as a form of property dualism. This places the theologian in the dilemma of committing to epiphenomenalism and so denying that human beings act to achieve purposes. It seems then that free will appears to require substance dualism which brings us back to the basic anthropological position most theologians have espoused for two thousand years.
There are many other points at which naturalism has adversely impacted theology, and many more at which it continues to undermine our contemporary culture. It is now time for theologians to confront naturalism straight on, and Naturalism: A Critical Analysis provides an excellent point from which to begin.
This review originally appeared in International Journal of Systematic Theology.