Religion & Law

Of Philosophers And Scientists

By John Pieret

PZ Mxyzptlk has a post on Alvin Plantinga's evolutionary argument against naturalism, as summarized in an article at Christianity Today.

I think PZ underestimates the philosophical sophistication of the argument (which, of course, does not mean it is either correct or true). The Wikipedia article on the argument shows that there is a lot of nuance going on and, indeed, an entire collection of objections to the argument and Plantinga's responses has been published.

I won't pretend to have studied Plantinga's argument or the responses thereto beyond the Wikipedia article and a few expositions of it by Plantinga and other theists, so my thoughts on it are best described, charitably, as preliminary.

PZ states:

In Plantinga's world, if we queried the inhabitants with some simple question, such as, "Is fire hot?", 50% would say no, and 50% would say yes. This world must be populated entirely with philosophers of Plantinga's ilk, because I think that in reality they would have used experience and their senses to winnow out bad ideas, like that fire is cold, and you'd actually find nearly 100% giving the same, correct answer. Plantinga does not seem to believe in empiricism, either.

Of course you are more likely to achieve your goals, and of course you are more likely to survive and reproduce if your beliefs are mostly true. ...

... This means that the neurophysiology that caused or produced that behavior has also been adaptive: it has enabled them to survive and reproduce. But what about their beliefs? These beliefs have been produced or caused by that adaptive neurophysiology; fair enough. But that gives us no reason for supposing those beliefs true. So far as adaptiveness of their behavior goes, it doesn't matter whether those beliefs are true or false.

Plantinga states that he is not attacking the theory of evolution,[16] which only yields the self-contradiction when connected with philosophical naturalism but is not equally inconsistent with theism.

He's reduced to a bogus either/or distinction. Either we are organic machines that evolved and our brains are therefore collections of random beliefs, or ? and this is a leap I find unbelievable ? Jesus gave us reliable minds.

The problem, as several thinkers (C. S. Lewis, for example) have seen, is that naturalism, or evolutionary naturalism, seems to lead to a deep and pervasive skepticism. It leads to the conclusion that our cognitive or belief-producing faculties?memory, perception, logical insight, etc.?are unreliable and cannot be trusted to produce a preponderance of true beliefs over false. ...

Clearly this doubt arises for naturalists or atheists, but not for those who believe in God. That is because if God has created us in his image, then even if he fashioned us by some evolutionary means, he would presumably want us to resemble him in being able to know; but then most of what we believe might be true even if our minds have developed from those of the lower animals.

(First, an amusing aside: footnote [7] is an acknowledgment of the assistance of someone else in doing those calculations. He needed help from an expert to multiply simple probabilities? Does being a philosopher mean you're incapable of tapping buttons on a calculator?)

Caerleon, North Wales, June 19, 1869.

I am much obliged to your Correspondent¹ of June 5 for having pointed out a great error in my 'Origin of Species,' on the possible rate of increase of the elephant. I inquired from the late Dr. Falconer with respect to the age of breeding, &c., and understated the data obtained from him, with the intention, vain as it has proved, of not exaggerating the result. Finding that the calculation was difficult, I applied to a good arithmetician; but he did not know any formula by which a result could easily be obtained; and he now informs me that I then applied to some Cambridge mathematician. Who this was I cannot remember, and therefore cannot find out how the error arose. From the many familiar instances of rapid geometrical increase, I confess that, if the answer had been thirty or sixty million elephants, I should not have felt much surprise; but I ought not to have relied so implicitly on my mathematical friend. I have misled your Correspondent by using language which implies that the elephant produces a pair of young at each birth; but the calculation by this assumption is rendered easier and the result but little different. A friend has extended your Correspondent's calculation to a further period of years. Commencing with a pair of elephants, at the age of thirty, and assuming that they would in each generation survive ten years after the last period of breeding?namely, when ninety years old?there would be, after a period of 750 to 760 years (instead of after 500 years, as I stated in 'The Origin of Species'), considerably more than fifteen million elephants alive, namely, 18,803,080. At the next succeeding period of 780 to 790 years there would be alive no less than 34,584,256 elephants.

CHARLES DARWIN

Full post as published by Thoughts in a Haystack on May 30, 2009 (boomark / email).