Modern brain research has reignited debate over a central question of philosophy: What is the relationship of body and mind? Specifically, how do the workings of the brain relate to our subjective thoughts, feelings and sense of personal identity? As Nobel Prize-winner Eric Kandel and his colleagues put it in their textbook, "Principles of Neural Science," "We are dealing here with biology's deepest riddle: the neural representation of consciousness and self-awareness."
Two kinds of answers have been offered to this riddle. The first claims that the mind is nothing but the brain. Every aspect of mental life can be entirely and completely explained as a product of the physical properties of neural functioning.
The second regards the mind and brain as mutually interdependent in ways that are not adequately explained by a strictly physicalist theory. The complexities of mind-brain interactions require a more dynamic approach to their further investigation.
The first kind of answer might appear to be more scientifically respectable -- more rational, more factual, more grounded in empirical research. But is it?
Consider the following passage from Adam Zeman's highly regarded "survey of neuroscience "A Portrait of the Brain." This is an otherwise excellent book about the evolution and functioning of the brain. In the final chapter, however, Zeman, a professor of cognitive and behavioral neurology at the Peninsula Medical School in the U.K., admits that his physicalist answer to the mind-body riddle is ultimately rooted in a bias against religion:
Sometimes, when we're perplexed, in a dilemma, we have to trust to the stronger of two conflicting intuitions, particularly if we have a hunch that one of the two is flawed. For me, though clearly not for everyone, the intuition that mind is continuous with life, just as life is continuous with matter, is very strong. I suspect that the opposing, 'dualistic,' intuition, that mind-stuff or mind-properties are of a different order from material ones, originates at least partly in the tenacious supernatural conception of the soul. Even people who long ago abandoned any formal faith continue to be influenced by an intellectual history in which religion has been immensely formative. Abandoning the soul will not come easily.
In the preceding paragraphs, Zeman acknowledges that philosophers like Thomas Nagel, Colin McGinn and David Chalmers have raised devastating critical questions about physicalism that he cannot refute. Yet he decides to accept physicalism anyway, based on what he calls a "hunch," a strong "intuition," and something he "suspect(s)" about the crypto-religious beliefs of those who do not accept physicalism.
These personal sentiments may be enough for Zeman to persuade himself, but they certainly do not qualify as a rational, evidence-based argument in favor of physicalism.
I don't know why, after 190 pages of well-referenced scientific discussion, Zeman decides at this point to bring up religion and make broad, data-free assertions about its historical and psychological influence. Doing so does not help his case. Quite the contrary. It suggests that at least some of the appeal of physicalism has nothing to do with scientific evidence but rather with a general sense of antipathy toward religion.
As neuroscientific research speeds forward into the future, propelled by large-scale initiatives like President Obama's Brain Activity Map, we should be on the lookout for unwarranted and ill-informed assumptions about the role of religious beliefs, practices and experiences in people's lives. Let's focus on the evidence, avoid prematurely conclusive theorizing and keep an open mind about the big-picture implications of new discoveries as they emerge.