The Self and Its Brain: An Argument for Interactionism
by Karl R. Popper, by John C. Eccles
Springer International, 597 pp., $17.90
“What is mind?”—no matter
“What is matter?”—never mind
(from Punch magazine, 1885)
That thinking is something which goes on in the brain is a proposition to which we all assent unless we are being deliberately “difficult” about so commonplace a belief. Yet the evidence that it does so is very circumstantial and indirect, and some philosophers have expressed doubts about the matter. Mind, they have argued, is not a “thing” for which a place can be allocated. But from a commonsensical point of view the evidence that makes us think of the brain as the seat of thinking and as the fountain of voluntary action is too persuasive to be dismissed.
The book that prompts these reflections gives us an opportunity to eavesdrop upon an extended dialogue between Karl Popper, whom many regard as the world’s foremost living philosopher, and John Eccles, the Nobel Prize-winning neurophysiologist. Between them they try to clarify a problem that neither thinks is likely to be wholly solved: the problem of the relationship between mind and the various physical performances of the nervous system.
It is a problem upon which two extreme views have been held: at one extreme, that Mind is a thing apart which cannot be said to be in any way embodied—for mind belongs to a quite different “semantic category” from nerve impulses and the like. At the other extreme is the uncompromising materialism that is embodied in Charles Darwin’s question: “Why is thought being a secretion of brain more wonderful than gravity a property of matter?” Without going to the other extreme, as Darwin did, I feel confident that the dismissive “category” argument is principally a defense by orthodox philosophers against what they have interpreted as another attempted usurpation of their subject matter by those pesky scientists. It is a poor argument anyway: heredity and high molecular weight polymers also belong to different semantic categories; nevertheless genetic memory is physically embodied in the order of the nucleotides which, strung together, form the giant polymer deoxyribonucleic acid (DNA): I shall try now to explain the notion of a semantic category.
Consider a sentence such as “the cat sat on the mat” and imagine a blank, to be filled in arbitrarily, in place of the word “cat.” Clearly we could substitute the word “dog,” “mouse,” or—meaningfully, though implausibly and perhaps mistakenly—”elephant.” On the other hand we could not substitute “foreign exchange deficit,” which would not be just erroneous or unlikely, but downright meaningless because it belongs to a different semantic category. Some philosophers, led by Gilbert Ryle, take the view that thinking, willing, and other such acts of mind belong to a different semantic category from nerve impulses and other traffic of the brain. To attribute an act of mind to something that goes on in the brain—or to say that a state of mind has no physical effects on the brain—is thus a category blunder as elementary as to say that “the …