Letter to the Editor


Donald MacKay and Semi-materialism

Oliver R. Barclay Publications 
Secretary Christians in Science 
8a Southland Rd. Leicester LE2 3RJ

From: PSCF 43 (June 1991): 141-142 

William Dembski, in his article "Converting Matter into Mind" in the December 1990 issue of the journal, I think fundamentally misunderstands the position of the late Donald MacKay when he charges him with being a semi-materialist. He quotes him as saying, "No change can take place in the conscious experience reported in a higher-level story without some corresponding change in the stories to be told at the lower level (though again not conversely)." He then goes on to say, "The phrase `not conversely' is decisive: it demonstrates that he takes the lower level as fixing the upper level. This is supervenience."

He has earlier described supervenience in terms of "there is no difference without a physical difference." This Dr. Dembski says means that man's soul and spirit "are not only inseparable from the body, but actually derived from the body." Now it seems to me that his logic is at fault. If, as MacKay says, you cannot make the changes at a higher level without some corresponding change at the lower level (though not conversely), then his point surely is precisely the opposite of what Dembski concludes. It is that you can have changes at the lower level which do not affect changes at the higher level. You can lose part of your brain without it having any detectable effect on your mind and psychological and spiritual powers. On the other hand, every change in your mind has some effect in the brain corresponding to it. This is the opposite of supervenience and I do not understand how Dr. Dembski charges MacKay and those who think like him, with semi-materialism.

Surely the position is that the higher level realities are in this life "embodied" in the physical framework. That does not mean that they are fixed by the physical framework. MacKay certainly held that even if the physical framework were perfectly describable in scientific and mechanistic terms, there would still be freedom of choice (see several articles on "The Logical Indeterminacy of a Free Choice.") Dr. Dembski seems to me to try to give us two alternatives. Having demolished the one he says we must accept a sophisticated version of the God-of-the-gaps. It is good to have someone defending that position, and he is not alone, but MacKay was constantly arguing for a third alternative that is neither semi-materialism nor God-of-the-gaps, but thought in terms of complimentary aspects of reality, each in principle complete on their own level and integrated in ways which he discussed, but in which the lower level descriptions neither determine nor explain in full the higher level realities.

Dr. Dembski seems to think that all who work in cognitive science are trying to debunk the existence of other realities. MacKay, who worked in this field, and was an international expert in it, did not hold that view, but rather that we should make every effort to explain what we can in terms of scientific categories while recognizing the limitations of science if it should try to describe the spiritual realities which inter-penetrate the lower level realities in a way somewhat analogous to that in which a computer programme relates to the hardware. It was MacKay who coined the phrase "nothing buttery" to attack the very position of which he is here accused. The higher level realities are not merely the sum of their parts and cannot be adquately described in those terms, but that does not allow a sort of detached "supernatural" realm in which the human spirit can function without any relation to physical reality...at least not in this life.