This is a book about the metaphysics of the mind/body problem. Metaphysics (or “ontology”) is the study of what exists (Aristotle called it the study of “being”). To many people today metaphysics seems anachronistic. Haven’t we settled the issue of what exists, they might ask, in favor of the physical universe? And isn’t natural science the way we produce knowledge about this universe? How could more work in metaphysics possibly generate any persuasive arguments, if “metaphysics” is not simply “physics”? Arguments about the relationship between the mind and the body that aren’t grounded in empirical research of some sort can’t hope to be legitimate in a world awash in data from experimental psychology, neuroscience, computer science, evolutionary biology, linguistics and the myriad of interdisciplinary areas of research that today we call “cognitive studies.” Isn’t a metaphysician a mere poet of speculation? Diverting at best, but such a person has no hope of producing useful knowledge. That, anyway, is often the initial reaction one meets with the topic of the metaphysics of the mind/body problem. I will respond to this initial “meta”-challenge in two ways.
First, I completely embrace the spirit, and much of the letter, of this initial objection. I too take it as axiomatic that what exists is the physical universe (by “physical” I mean the universe of matter and energy, or maybe matter/energy; I don’t pretend to be sophisticated about theoretical physics). I don’t think that humans are composed of physical bodies and non-physical souls, like a traditional mind/body dualist. I think that humans are physical through and through, animals that evolved here on earth through a long process of evolution the contingencies of which were, and continue to be, bounded by the constants of biology, chemistry, and physics. I don’t expect to discover that humans are angels, or that the physical universe is an illusion and humans are non-physical spirits, or anything like that.
The universe is as magical, mysterious and mystical as it may be; I don’t know anything about the ultimate composition or nature of the universe. I have no interest in making a brief for reduction, as if natural science can address every one of our wonders, or even potentially could. I don’t even know what we’re talking about when we use that kind of language. My claim is much humbler: whatever nature in general is like, humans are like that. Humans are not miracles, if a “miracle” is defined as an exception to the laws of nature. Call me an “anti-humanist.” I hold the anti-humanist view simply because I know of no reason to think that humans are miracles; I stress it because a deeply internalized assumption of human exceptionalism continues to be a barrier to progress across the whole range of the behavioral and cognitive sciences.
Which brings me to the second response to the objection that metaphysics is anachronistic: it is certainly not true that the contemporary society of educated people embraces anti-humanism as I just defined it. A great many college students, most people walking down the street and the overwhelming majority of the world’s population today continue to think that the mind is something distinct from the body or, at least, that mental phenomena cannot be adequately described and explained in wholly physical terms. This conviction has various sources that range from traditional, usually religion-based beliefs about souls, afterlives and so forth to more modern notions, such as the view that a naturalistic view of human nature is perniciously reductive and to be resisted by the liberal-minded, or perhaps that science itself is nothing more than a socially-constructed “conceptual scheme” with no particular claim to legitimacy, and so on. For another thing, very sophisticated versions of human exceptionalism exist in the academy today (for example among some linguists), such that it is by no means established conventional wisdom that physical science subsumes psychology by metaphysical axiom.
Metaphysics is not something that is replaced by physics. Physicalism is a particular metaphysical position. Everyone has metaphysical assumptions, articulated or not, whether they want to or not, and they always will. The person who chafes at the idea that there is still a need for explicitly metaphysical discussion is claiming that our shared metaphysical assumptions are currently stable, not that “there is no such thing as metaphysics,” although they may unreflectively put it that way. It’s true that physicalism is currently the ruling metaphysical paradigm among cognitive scientists, psychologists, philosophers and so on, and I too labor within this paradigm, albeit with some important qualifications that are discussed in the second part of Chapter Two.