Ludwig Wittgenstein once remarked that it is not how the world is that is astonishing, but that it is. Equally extraordinary is the fact that the world is intelligible to the human mind, when it might easily not have been so. This raises several fundamental metaphysical questions: if the universe is simply the product of random, irrational causes, why is it so consistent, predictable, and law‐like? What explains the human mind's unique capacity to make sense of reality? Why is there such a close correspondence between the knower and the known?

The renowned medic and philosopher Raymond Tallis tackles these questions with élan in his new monograph, Logos: The Mystery of How We Make Sense of the World. A self‐confessed atheist, Tallis admits to formerly having been inclined toward scientism. However, painfully aware as he now is of the epistemic limits of human understanding, he does not pretend to be able to explain how consciousness and matter can relate to one another—or to “solve” the mystery of Logos (the comprehensibility of the world). Instead, by exploring the work of philosophers, scientists, and theologians who do purport to provide answers to these questions, he offers a scintillating tour through the conceptual landscape of the contemporary debate.

The structure of the book is impeccably logical. After an introductory chapter laying out the main themes, Tallis provides a critical examination of two reductionist theories that have attempted to explain Logos: idealism and materialism/physicalism. Idealism holds that “the comprehended natural world is internal to the mind that comprehends it” (53). In its most extreme form, it claims that reality consists solely of minds and their ideas. Space and time are merely forms of our human experience rather than properties of things in themselves. Tallis concedes that the measurement of space and time are activities of the human mind, but he argues that it is surely a matter of objective fact that, for instance, the universe has a certain diameter, or that E = mc ². A further problem with idealism, he argues, is that it leads ineluctably to solipsism and the “problem of other minds,” and removes rather than addresses the mystery of the intelligibility of the world, because “the comprehended world is dissolved without remainder into the comprehending mind” (54). Idealism thus fails to explain the origin of a world distinct from human minds, and it does not even begin to address the problem of how it is that the mind can come to acquire knowledge of that world.

Materialism/physicalism, in contrast, claims that our minds are nothing more than the product of evolutionary processes and are therefore internal to nature. Seemingly nonphysical properties—such as minds, consciousness, and experience—are merely epiphenomena that arise out of the physical activity of the brain. Materialists are committed to the view that all will eventually be explained in terms of neural mapping or other matter‐based techniques. Tallis is suspicious of the assumption that mind is an “emergent property” from matter, arguing that it does not make evolutionary sense for creatures to be conscious: in terms of survival, for instance, consciousness offers no clear selective advantage.

My problem with this part of the argument was in identifying what Tallis might understand by the term “consciousness.” He is presumably not saying that “it is better to be a tree than a dog,” because trees (not conscious) “survive longer than dogs” (conscious). He appears, rather, to be asserting that self‐awareness offers no clear evolutionary advantage. Yet the mind that is self‐aware (i.e., human) is more highly “developed” than the one that is not (e.g., that of a dog) and so does have an evolutionary advantage. Humans have the ability to survive precisely by using a mind that has much greater capacity, demonstrated in that mind's self‐awareness—a self‐awareness that is integral to its problem‐solving ability. As Tallis points out, human cognition differs radically—not only in degree, but also in kind—from that of all other species. There is therefore some substance to his claim that the human capacity to acquire knowledge cannot be “causally eliminated” by assuming that there is a seamless continuity between it and animal sentience. He is brave to challenge such a materialist orthodoxy, and his critique echoes similar attempts by philosophers such as Thomas Nagel.

As Tallis rightly indicates, the difficulty with both the idealist and the materialist attempts to “solve” the mystery of human consciousness and knowledge is that one crucial aspect of existence is ignored or denied. In his view, neither account offers a satisfying answer to the problem of the comprehensibility of the universe. Little wonder that this “divorce between how the world looks and feels, and our scientific understanding of it comes to feel like a deep cognitive wound” (172). In the remaining chapters, he attempts to heal this “cognitive wound” by affirming the reality of a world “out there” as well as a genuine knower “in here.” Our knowledge, he says, arises out of a complex relational interplay between knower and known.

So far, so good. But it is at this point that his analysis runs into more serious difficulties. He argues, for example, that an insuperable gap exists between objects and our cognition, and that this “opacity” between knower and known means that we may never fathom the reason for our ability to “make sense of things.” We must remain “ontologically agnostic” about why the world is rational. The mystery of the Logos of the world is so impenetrable that it is impossible to answer.

Tallis insists, however, that a “supernatural” explanation must be avoided at all costs, on the grounds that it is empirically unknowable. Nevertheless, he must see that, if mind and world truly are open to one another, then, while being careful to uphold the objective reality of both mind and matter, it makes perfect rational sense to accord a certain causal priority to mind over matter. He concedes that, if the materialist/physicalist conception of nature were, in essence, sound, we would be hard put to account for the existence of consciousness. But it would be even harder to explain how consciousness could fathom the truth of physical reality.

Tallis would do well to engage with the work of the Christian philosopher and theologian David Bentley Hart. In his profoundly impressive book The Experience of God: Being, Consciousness, Bliss (New Haven and London: Yale University Press, 2013), Hart takes it as given that the mind really does acquire knowledge from what would otherwise be a succession of physical states devoid of meaning. In fact, he argues, the world becomes more intelligible to us the more we are able to abstract it into concepts. For instance, something becomes fully intelligible to us when we are able to say that we have an idea of it that can be grasped according to the simplest abstract laws. This, for Hart, is the highest degree of intelligibility, and means that, while “we may or may not be Platonists in our metaphysics … we certainly must be practical idealists in our epistemology” (233). It therefore makes perfect sense that a sizeable proportion of Greek philosophers and medieval scholastics took it for granted that “the ideal dimension of things, their intrinsic intelligibility, was not only a real property of their existence but in some sense was identical with existence itself” (233). Hart's conclusion is that, if that is so, it raises the following questions, all of which lead to a necessary theological supposition:

What… is an idea other than the product of a mind? What is a concept other than the expression of a rational intentionality? And how, therefore, could being be pure intelligibility if it were not also pure intelligence—the mind of God, so to speak? (233)

It is disappointing that Tallis, in what is an otherwise excellent book, rejects tout court the possibility of there being a divine underpinning to the intelligibility of the universe. This seems more like atheist prejudice than well‐reasoned argument. It also suggests that he retains some sympathy with the scientism of his youth, despite his protestations to the contrary. These faults do not, however, detract overall from the fascinating story he has to tell, and his book is a thoroughly enjoyable read.