In The Descent of Man (Penguin Classics, 2004), Darwin did seem to be a reductionist when he declared that the differences between human beings and the other animals was only a difference in degree and not in kind:
"Some naturalists, from being deeply impressed with the mental and spiritual powers of man, have divided the whole organic world into three kingdoms, the Human, the Animal, and the Vegetable, thus giving to man a separate kingdom. Spiritual powers cannot be compared or classed by the naturalist: but he may endeavor to shew, as I have done, that the mental faculties of man and the lower animals do not differ in kind, although immensely in degree. A difference in degree, however great, does not justify us in placing man in a distinct kingdom" (173).Against this apparent reductionism, Scruton argues that human beings are irreducibly different in kind from other animals: "We are animals certainly; but we are also incarnate persons, with cognitive capacities that are not shared by other animals and which endow us with an entirely distinctive emotional life--one dependent on the self-conscious thought processes that are unique to our kind" (29-30).
Other animals are conscious, Scruton contends, but only human beings are self-conscious in being able to say "I," who thus become persons rather than mere objects.
Other animals can communicate, but only human beings have language, which allows them to tell stories about themselves and their world; and thus they can live in imagined symbolic worlds that they have created for themselves, which includes the religious symbolism of stories about the divine.
Other animals are social beings who can enforce rules of social cooperation, but only human beings have a moral sense by which they judge the conduct of themselves and others as right or wrong, good or evil, just or unjust.
Scruton concedes that all of these distinctively human traits depend upon biological capacities in the brain that are objectively observable and thus open to scientific explanation. And yet, he argues, the uniquely human experiences of self-conscious awareness, understanding language, and moral judgment are inward subjective experiences of the mind that cannot be outwardly seen through objective observation, and therefore they cannot be studied by the natural science of biology.
In all of this, Scruton assumes a fundamental dualism that originated in nineteenth-century Romanticism, which is conveyed in Wilhelm Dilthey's separation of Geisteswissenschaften (human sciences or sciences of the mind or the humanities) and Naturwissenschaften (natural sciences) (12, 22-23, 46). The natural sciences seek causal explanations of the objectively observable realm of Nature. The humanities seek interpretive understanding of the subjectively experienced realm of Spirit or Mind, which is the uniquely human realm. This kind of distinction is assumed in the way academic disciplines are organized in Western culture: the natural sciences and social sciences are separated from the humanities.
Scruton illuminates this distinction through an analogy (30-32). When painters paint on a canvas, they create physical objects by physical means. When we look at the painting, we are looking at the physical blobs of paint on the physical canvas. But if we see a face in the painting, the face is in some manner something more than the physical blobs of paint. Seeing the face is a subjective experience in our inward mental experience. Natural science can explain the physical and chemical properties of the painting as objectively observable phenomena. But our subjective awareness of the face is an inward mental experience that cannot be reduced to the physical and chemical properties of the painting. Similarly, we might say that persons are to their bodies as seeing the face in the painting is to the physical blobs of paint on the canvas.
Personhood is an emergent feature of the human organism that depends on the biological capacities of the organism but without being fully reducible to those biological capacities. The brain scientist can explain the natural physical and chemical properties of the brain that make personal subjectivity possible, but this cannot fully explain the subjective experience to which a person has direct access, but which is invisible to the scientific observer. We can design machines that paint pictures, but we cannot assume that those machines see faces in their pictures. Thus, the human person is an emergent entity rooted in the human animal body but belonging to a higher realm of reality beyond biology.
Emergence occurs when quantitative differences pass over a critical threshold of complexity to become qualitative differences: differences of degree become differences in kind. So, for example, with rising temperature, ice becomes water, and then water becomes steam. Scruton concludes: "What we are trying to describe in describing personal relations is revealed only on the surface of personal interaction. The personal eludes biology in just the way that the face in the picture eludes the theory of pigments. The personal is not an addition to the biological: it emerges from it, in something like the way the face emerges from the colored patches on a canvas" (41).
The straw man fallacy in Scruton's argument is in his false assumption that biologists must be reductionists who fail to see the need for the idea of emergence as part of their scientific explanation of subjective mental experience. In fact, as I have argued in various posts (here, here, here, and here), many biologists, beginning with Darwin, have recognized biological emergence.
Despite Darwin's explicit statement that humans differ only in degree, not in kind, from other animals, he implicitly recognized all the differences in kind that are stressed by Scruton. That is to say, that Darwin recognized that human beings have some traits that other animals do not have at all.
Darwin noted that self-consciousness is uniquely human: "It may be freely admitted that no animal is self-conscious, if by this term it is implied, that he reflects on such points, as whence he comes or whither he will go, or what is life and death, and so forth" (105). Morality is also uniquely human: "A moral being is one who is capable of comparing his past and future actions or motives, and of approving or disapproving of them. We have no reason to suppose that any of the lower animals have this capacity. . . . man . . . alone can with certainty be ranked as a moral being" (135). And language is uniquely human: "The habitual use of articulate language is . . . peculiar to man" (107).
Darwin could implicitly affirm such emergent differences in kind without affirming any radical differences in kind. Emergent differences in kind can be explained by natural science as differences in kind that naturally evolve from differences in degree that pass over a critical threshold of complexity. So, for example, we can see the uniquely human capacities for self-consciousness, morality, and language as emerging from the evolutionary expansion of the primate brain, so that at some critical point in the evolution of our ancestors, the size and complexity of the brain (perhaps particularly in the frontal cortex) reached a point where distinctively human cognitive capacities emerged at higher levels of brain evolution that are not found in other primates. With such emergent differences in kind, there is an underlying unbroken continuity between human beings and their hominid ancestors, so there is no need to posit some supernatural intervention in nature that would create a radical difference in kind in which there is a gap with no underlying continuity.
Scruton agrees with this in that human uniqueness emerges from small steps in evolution without any need for positing some separate miraculous origin for human beings: there is "no impassible gap" (66).
Scruton and Darwin also agree about what Scruton calls "the mystery of the subjective viewpoint" (135). We can see the body through outward observation. But the mind is invisible, and we can know it directly only by our own inward experience of mental awareness; and therefore we can only infer mental experience in other human beings or other animals by interpreting their outward movements as evidence of inward subjectivity similar to our own. So, as Aquinas said, "the internal passions of animals can be gathered from their outward movements."
Darwin recognizes "the impossibility of judging what passes through the mind of an animal" (105). But he believes that scientists can make reasonable inferences about the invisible subjectivity of animal minds from careful observation of their bodily movements and bodily expression of emotions. And, of course, this is what ethologists do when they infer animal psychology from observational and experimental studies of animal behavior. Ethologists thus engage in scientific "mind reading." And, as we have seen in some posts (here), some ethologists see experimental evidence for other animals having a "theory of mind," so they read the minds of other animals. Oddly, Scruton ignores this when he asserts that interpreting animal minds is not part of science, but belongs only to the humanities and to ordinary folk psychology.
Scruton also ignores the scientific study of what Darwin called the "mental individuality" of animals (Darwin, 106), which includes the study of "animal personality" (a topic for various posts here and here). Scruton does admit that other animals show "shallow individuality," although he insists that only human beings show "deep individuality" (80-82).
And while Scruton denies that other animals have morality, he does admit that apes show "near equivalents of punishment, appeasement, and reconciliation" (84).
If it is possible for biological scientists to study the mind--the Geist--then they can study those uniquely human traits that arise through mental subjectivity--self-consciousness, morality, and language--and thus biology can account for the fullness of human nature as including both body and mind. If this is true, then biology includes the Geisteswissenschaften as well as the Naturwissenschaften.
And this biological study of human psychology includes the biological study of religious psychology as rooted in the evolved human propensity for detecting intelligent agency: just as we read the invisible minds of other human beings and other animals, we read the invisible mind of God. Our natural desire for religious understanding is rooted in our natural desire for understanding invisible minds. Evolutionary psychologists can agree on this without agreeing on whether this religious psychology points to the real existence of a divine mind, which has come up in posts (here).
In his affirmation of atheistic religiosity, Scruton affirms religious longing as part of human nature grounded in evolved human psychology, but without affirming the doctrinal truth of that natural religion.
Scruton's atheistic but religious conservatism resembles the position of other conservatives such as Peter Augustine Lawler, who have tried to argue that evolutionary science provides a true, but only partially true, account of human nature.