David Hume was a well-known Scottish historian and diplomat in his own time, but is better remembered today for his philosophical works. In his An Enquiry Concerning Human Understanding, Hume writes, “There is no method of reasoning more common, and yet none more blameable, than, in philosophical disputes, to endeavour the refutation of any hypothesis, by a pretence of its dangerous consequences to religion and morality.” In other words, the truth or falsity of an idea cannot be determined by whether one likes the idea or its implications. This seems quite obvious, but Hume wrote that it was a common problem in his time, and not much has changed since then.
The theory of evolution has often been the target of such critiques. The beginning of the Christian fundamentalist movement in the early 20th century was in part a reaction to the seemingly atheistic implications of explaining life without reference to a creator. William Jennings Bryan, famously known for his role in the Scopes “Monkey Trial,” opposed evolution largely because he saw it as undermining the existence of the soul as well as any objective basis for morality. Without a Creator-God who was also a Law-giver, morality becomes a personal or cultural choice and “good” and “evil” become euphemisms for whatever we like or don’t like.
Contemporary critics of evolution continue in this same vein, linking Darwinism to the Nazi Party and decrying naturalism for its apparent destruction of the possibility of an objective morality. The problem is that none of this actually has any bearing on whether or not evolution is true. To be fair, I do not usually see critics like Dembski or Behe actually using this as an argument against evolution, but it does seem to come up frequently in their blogs or other venues (e.g. the film Expelled).
Defenders of evolutionary theory are often guilty of the same tactic. From Darwin himself to contemporary philosophers and many evolutionary theorists in between, the argument has been made that if God did create nature he either did a terrible job of it or is an evil being (e.g. for making parasitoid wasps). Leaving aside the oddity of arguing for evolution by engaging in divine psychology, the arguments themselves are of course irrelevant to whether or not nature is a product of a creator. If indeed things like the parasitoid wasp were created on purpose, then it would be a genuine theological problem. But we must first accept that it was created, and then deal with the implications. Evolutionary theorists cannot reject the idea of creation because they do not like the implications. To be fair, no evolutionary biologist has argued for evolution based entirely on such theological objections, but these types of objections are indeed a common part of defenses of evolution.
Judging an idea by its consequences seems to be a natural reaction for most of us. While it may be worthwhile to examine the consequences of ideas one judges to be false, Hume is certainly correct that distasteful consequences should play no role in determining the truth of the idea in the first place.