Modern science has been hugely successful in its observation and understanding of the natural world, but this very success has led to what the American philosopher John Searle has called “the heroic age‐of‐science maneuver,” that is, the confident assumption that science can, and will, explain everything. Such positivist faith in the scientific method has served to undermine any idea of theistic intervention within what is believed to be a closed physical system: the idea of God becomes redundant as a causal explanation of what are seen as entirely autonomous processes in the natural world. Indeed, because the “laws of nature” are perceived by many as immutable, the notion that God could, even in principle, somehow break in from the outside and “violate” the very laws he himself has established seems contradictory.

In her monograph Divine Action and the Human Mind, Sarah Lane Ritchie, a Research Fellow in Science and Theology at the University of St Andrews, tackles head‐on the problem of how “divine action” might still be possible in such a closed universe. She is at pains to defend a form of “theistic naturalism,” a notion which will strike many as oxymoronic or even bizarre. After all, in philosophy, the term “naturalism” usually implies the non‐existence of the supernatural in general, and the divine in particular.

Ritchie is especially hostile to any suggestion that God can act through the human mind as a separate spiritual entity from the body. Her avowed aim is to refute mind–body dualism, and to offer instead a robust defense of a physicalism, which reduces mind to brain. For her, it is clear that “the mind just is the brain–body–environment system” (14). Consciousness should not be regarded as in any sense an immaterial phenomenon. Indeed, she confidently asserts that, while it once appeared “obvious” that the mind is inherently spiritual, today the “consensus” among philosophers and neuroscientists is that physicalism is the most convincing explanation for human mentality (214). What she apparently fails to realize, however, is that, even if her claims about such a consensus were true, mere agreement among scholars is no guarantee of truth. Dualism remains very much alive, notwithstanding its considerable philosophical difficulties. But Ritchie appears unable to appreciate that there are even more profound problems with physicalism. The “hard problem” of how consciousness can emerge from non‐conscious physical processes is simply brushed aside. And she never really comes to grips with the central role of intentionality to consciousness, nor with the intrinsic inability of matter to possess it, or of computers to ascend from the execution of algorithms to the grasping of concepts. Moreover, scientific theories are themselves artifacts of human consciousness and rationality. The attempt to use science to show that consciousness and rationality are nothing more than physical processes only serves to vitiate any confidence we might have in science itself, and in our capacity to search for and identify truth through the scientific method. Seemingly “rational” explanations of the physical fons et origo of consciousness are thus in danger of becoming self‐contradictory. Consciousness is not what needs explaining: consciousness is what does the explaining.

Upholding naturalism is crucial to Ritchie's project because of her desire to reject the “standard causal joint model” of divine action. The term “causal joint” was coined by the English philosophical theologian, Austin Farrer, and refers to the point at which divine action impinges on the world. Ritchie rightly observes that the idea of a transcendent God intervening in the world from outside becomes deeply problematic once we view nature as governed by prescriptive natural laws. A less rigid model of laws that perceives them not as prescriptions, but as descriptive of mere general regularities, is unlikely to cause such difficulties. Perhaps the whole notion of physical laws that cannot be violated is itself fundamentally flawed. However, clearly indebted as she is to the work of process theologians, Ritchie seeks to promote the concept of theistic naturalism, which emphasizes God's immanence. The physical universe, she maintains, “participates in the immanent God” (336). Unfortunately, this raises a key difficulty, which she herself acknowledges. Namely, any theistic naturalism that embraces the scientific picture of reality, but which, at the same time, tries to place it into a broader theistic context, is “self‐admittedly unfalsifiable and untestable” and thus becomes “wholly immune to scientific critique” (336). Ritchie attempts to extricate herself from this problem by claiming, in more traditional theological fashion, that as well as being immanent, God is also transcendent. This results in a tension between a deistic model, which perceives the physical universe as entirely autonomous, and a panentheism, which portrays God as within the universe, but also outside it. The temptation of sliding from here into a Spinozan pantheism is, of course, very great indeed.

In an effort to avoid such pantheism, Ritchie accepts the need for divine transcendence: “There must be a clean ontological break between God and nature” (247). However, the problem with this solution is that, by affirming the ontological reality of a transcendent God, this commits her to the reality of the non‐physical, a fact that only serves to undermine the main argumentative thrust of her book. For how can a monism which, by definition, excludes the possibility of an immaterial mind be sustained once the metaphysical reality of the non‐physical has been conceded? Ritchie began by wrestling with the problem of divine action within a closed, autonomous universe, but her philosophical aim of trying to hold together both naturalism and a strong sense of God as ontologically distinct from the world appears contradictory. If we are prepared to acknowledge the non‐physical reality of God, what stops us from accepting the non‐physical reality of mind and consciousness? Sadly, one looks in vain throughout the book for a satisfactory answer to this question. That said, the author has produced an intriguing volume that, one might hope, will stimulate fruitful dialogue between scholars working at the interface between science and religion.