(Redated post last published on 3 November 2011)
According to Nancy Pearcey and biologist Jeffrey Schloss (see here), Darwinian evolution implies there is nothing ethically wrong with rape. Why? Pearcey argues that Darwinian evolution and moral realism are logically incompatible:
In the words of sociobiology’s founder, E.O. Wilson, “the basis of ethics does not lie in God’s will”; instead, ethics “is an illusion fobbed off on us by our genes” because of its survival value. Those who accept Darwinian evolution, yet raise moral objections to A Natural History of Rape, are being inconsistent to their own foundational assumptions.
The rise of evolutionary psychology is forcing people to grapple with Darwinism’s profoundly nihilistic moral implications.
“A transcendent fulcrum for morality is possible only if there is a transcendent Designer,” Jeffrey Schloss, biologist at Westmont College, told World. This explains why, when feminist leader Susan Brownmiller objected to Thornhill’s theory, he accused her of sounding like “the extreme religious right.” In short, Darwinism and its unpalatable moral implications are a package deal; protest, and you invite a return to the theistic worldview.
It’s an agonizing dilemma for evolutionists: Either they can be logically consistent to their starting assumptions, but end up with an inhumane worldview–or they can be true to their God-given sense of morality, at the cost of being inconsistent. (italics mine)
Given what Alvin Plantinga has taught us about the difficulty in establishing a a logical contradiction between theism and evil, I think it’s pretty clear that the same difficulty applies to an alleged logical contradiction between Darwinian evolution and moral objectivism. It is one thing thing to claim that phenomena like objective moral values are evidence for theism and against Darwinian evolution. It is quite another to claim that moral phenomena are logically incompatible with Darwinian evolution.To see the problems with this, let’s begin with some definitions. Let us define “Darwinism” as the belief that natural selection operating on random genetic mutation is the principal mechanism driving the evolutionary change that results in increased complexity. And let’s define “moral objectivism” as the belief that some moral claims are true in virtue of corresponding to actually existing objects or properties that function as truthmakers for the claims in question. Here, then, are the premises which Pearcey claims contradict one another.
(1) Darwinism is true.
(2) Moral objectivism is true.
Where is the contradiction? I do not find an argument for the existence of a contradiction in Pearcey’s article. All we find is the bald assertion, repeated over and over and in different ways, that there is such a contradiction. Indeed, we can make a stronger point. As Quentin Smith wrote in a totally unrelated context, “It cannot be shown, by substitution of synonyms for synonyms, that the relevant negations of these sentences are substitution instances of first-order predicate logic with identity.”
Theists don’t (and shouldn’t) accept such sloppy argumentation from atheists who present a logical argument from evil. They should not lower their standards when it comes to moral arguments for God’s existence or metaethical objections to atheism or Darwinism.
 Paul Draper, “Evolution and the Problem of Evil” in Philosophy of Religion: An Anthology(3rd ed., ed. Louis Pojman, Wadsworth, 1997), pp. 219-230.
 Quentin Smith, Ethical and Religious Thought in Analytic Philosophy of Language (New Haven: Yale University Press, 1997), 172.