There have been few books in recent years that have created as much discussion, in the academic world at least, as Thomas Nagel’s Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False. Critics of the explanatory reach (or what they think is an over-reach) of evolutionary biology were pleased to find an ally—or one who they thought was an ally—in an eminent philosopher who, despite his own atheism, was willing to reject a reigning materialist and reductionist account of nature and human nature.
More than anything else, it was Nagel’s challenge to and rejection of those philosophical principles that underpin so much of modern and contemporary reflection on nature that seemed to many to be especially troublesome. It is one thing to question particular conclusions in the natural sciences; it is quite another to argue against a priori assumptions about their content. Nagel thinks that, in principle—and this phrase is key—the contemporary natural sciences are incapable of providing an adequate description of nature and, especially, of human nature. Mental processes and judgments of value are real features of the universe, and yet they are inexplicable in the categories of the natural sciences, as these sciences exist today.
In mid-August, Nagel published a short summary, titled “‘The Core’ of Mind and Cosmos,” in the Opinionator column of the New York Times. For those who embrace an exclusively materialist view of reality, categories such as mind, value, and subjective experiences are often nothing more than words we give to describe purely physical phenomena. Nagel will have none of this. As he says, “biological evolution must be more than just a physical process, and the theory of evolution, if it is to explain the existence of conscious life, must become more than just a physical theory.”
Nagel thinks that we must discover, or perhaps re-discover, that there is an immanent order to nature, which needs to be part of any expanded science of nature. Mind, he says, “is not an inexplicable accident or a divine and anomalous gift but a basic aspect of nature that we will not understand until we transcend the built-in limits of scientific orthodoxy.” Nagel calls for a teleological naturalism that can describe an inherent directionality in nature.
Now, another contribution to the debate has appeared in the Opinionator, from Philip Kitcher, the John Dewey Professor of Philosophy at Columbia University. In his essay “Things Fall Apart,” Kitcher challenges what he thinks is Nagel’s core misconception: the commitment to “a complete metaphysical view” of reality.
This is no small disagreement, and Kitcher’s analysis, if correct, goes to the heart of scientific and philosophical endeavors. For this reason we should examine what Kitcher calls the “illusion of unity” that Nagel mistakenly embraces.
For Kitcher, Nagel and many others are wrong to think that there must be some master framework into which our accounts of reality must fit. Committed to the search for such a framework, scientists and philosophers debate the adequacy of various candidates. Hence, Nagel finds inadequate a particular framework—Neo-Darwinian materialism—and proposes the outlines for a naturalistic teleology that would include features of reality (mind, value, and so on) omitted in the framework he rejects.
Yet Kitcher thinks Nagel and his colleagues committed to this search are “in the grip of the Newtonian picture of science,” which seeks a generalized view of world. Those who ask questions such as “What is life?” are posing the wrong questions. “Don't ask what life is (in your deepest Newtonian voice),” Kitcher writes. Consider instead “the various activities in which living organisms engage and try to give a piecemeal understanding of these.”
Kitcher thinks that the proper attitude for a scientist or a philosopher is one of “decomposition.” Indeed, Kitcher tells us that this is precisely what the natural sciences do: they decompose the phenomena to be explained “into a number of different clusters.” The molecular biologist, for example, does not tell us what life is, but describes a particular function or set of functions of living organisms. Science will not tell us what life is; rather it will illuminate various features of living things.
Kitcher’s argument reflects the truth of ever-increasing specialization in the natural sciences. Neurophysiologists probe ever deeper into the complex functioning of the brain and the nervous system. Their empirical analyses do not account for mind or consciousness, neither of which is an empirical phenomenon. For Nagel, this failure requires a rethinking of what the natural sciences should accept as first principles. For Kitcher, it suggests that Nagel’s question about science is ill-posed. Any question informed by a metaphysical framework that looks for unified explanations of reality is off the mark.
Mind and value, for example, may not be illusory, but, Kitcher contends, “it might nevertheless be an illusion that they constitute single topics for which unified explanations can be given.” The future of the natural sciences in these areas ought to be one of greater “decomposition,” that is, increased specialized studies and “the provision of an enormous and heterogeneous family of models.”
So far so good, it might seem, until Kitcher invokes a principle of his own metaphysical framework: as specialization flourishes, at some time in the future “it may fall to some neuroscientist to explain the illusion of unity, a last twist on successful accounts of many subspecies of mental processes and functions.” As we examine with ever greater care the constituents of nature, we might have to conclude that the emperor has no clothes, that there is no real underlying unity to reality. Then, says Kitcher, perhaps “it will be clear that the supposed unity of mind and of value were outgrowths of a philosophical mistake, understandable in the context of a particular stage of scientific development, but an error nonetheless.”
Kitcher’s analysis reveals the temptation to think that the more we “decompose” phenomena into parts, the more likely we are to conclude that nature is simply parts within parts. We, however, need to look more closely at what it means for a thing to be one. To be a unity, to be one, depends on what the “thing” in question is. We could speak of a single living organism, a subatomic particle, a chemical compound, or the universe as a whole. We could even speak of the different senses of unity that apply to human products: from a work of art or a piece of music to a sentence or an entire novel. Unity takes many forms, but we cannot just conclude from this that unity is illusory.
A conscious living organism with mental capabilities, although highly complex, is truly a unity. Otherwise we could not speak of its functions, patterns of behavior, and the like. The activities of each entity have their source in the unity of the entity that acts. What sense does it make to speak of “its” behavior if there is not first of all an “it” to behave? To know what any thing is involves grasping in some sense how it is one; how it is the thing that it is.
Human beings are biologically one and psychologically one. The physical and chemical processes that are features of human life also possess characteristic unities. Unity does not mean homogeneity. Each of the various natural sciences studies the unity appropriate to its domain of inquiry. The different empirical sciences do function in the ways that Kitcher suggests. But it does not follow that any sense of a wider unity, for example, of a human being as a whole reality, is only an illusion. It is the function of a more general science of nature, traditionally referred to as the philosophy of nature, to describe this wider unity.
Jacques Maritain, the distinguished French philosopher of the last century, wrote an influential book, Distinguer pour unir [Distinguish in Order to Unite]. He recognized that in our search to understand the world and ourselves we must make distinctions; we must have various types of specialized knowledge. But we must not rest in discrete specialties—specialties which, after all, necessarily abstract from the unity of the entity we seek to know. We need to bring together our specialized knowledge in order to understand our world.
It is by a process of unifying diverse areas of knowledge that we come to understand, for example, what life is. The unifying is not simply the adding together of information from different specialties. Rather, it involves recognizing the unity of the whole through a new level of insight, dependent upon each of the specialized sciences, but involving a new plane of understanding.
It is the role of natural philosophy to perform this unifying function for the natural sciences, whereas metaphysics unifies knowledge from the natural sciences with exclusively non-material features of reality. Whatever one might think of the adequacy of Nagel’s specific proposal to broaden the scope of science, his basic intuition to enlarge our intellectual vision remains sound. Natural philosophy helps us to distinguish between those things that are truly one, in the various senses of one, and those things that are accidental heaps of discrete parts. The unity of a chemical compound, for example, is different in kind from the mere contiguity of its diverse elements. Water is more than the sum of hydrogen and oxygen, even though it has no additional material components.
Understanding unity in nature is not only a theoretical or speculative concern. If a human being is not one thing—that is, if he or she does not possess an intrinsic principle of unity, precisely as a human being—then no one can really be a cause of his or her own activity. Causal action flows from the nature of things. Human beings think and act; it is not the brain that thinks nor the body that acts. Without real human causal agency—agency that would not exist absent a human being’s being one thing—there could be no human responsibility for any action. In such a scenario, ethics becomes the real illusion.
William Carroll is the Thomas Aquinas Fellow in Theology and Science at Blackfriars Hall and a member of the Faculty of Theology and Religion of the University of Oxford.