It would be scandalous if there were university departments in which Ptolemaic cosmology still predominated, if there were journals devoted to publishing clever papers by Ptolemaic scholars, and if Ptolemaic scholars were oblivious to the challenge posed by Copernican cosmology.
An even more scandalous situation exists with respect to ethical theory. It has been more than 150 years since Darwin published On the Origin of Species but ethicists are still grinding out papers about the theories advanced by Bentham and Kant, and their intellectual descendants. And many ethicists who lost hope that either of those approaches would ever succeed have responded by returning to Aristotle. They are all oblivious to the challenge posed by the theory of evolution by heritable variation and natural selection, as are proponents of the divine command theory and Thomistic natural law.
In the long run, natural selection would destroy the lineages of people who tried to live according to any of those theories. First, people can violate the obligations the theories hypothesize. Consequently, evolution can create dispositions to act discordantly with the theories. Second, the theories require their adherents to do something other than try to maximize their genetic legacies. Thus, trying to live according to the theories would reduce fitness to a significant extent. And, third, ‘strongly inadaptive features hold little prospect for an evolutionary legacy because natural selection must soon eliminate them.’ [Stephen Jay Gould, The Structure of Evolutionary Theory (Cambridge, MA: Belknap Press, 2002), p. 1247.] The upshot is that if any non-evolutionary theory were true, humanity would have ended up being amoral. Since humanity still cares about morality, the non-evolutionary theories must all be false.
The question that arises in these circumstances is why people continue to promote these theories. One factor, I suspect, is the availability error. The theories are regular fodder in courses on ethics, which results in people taking them more seriously than they should, which results in their being taught in ethics courses. Another is probably that you can make a good living contributing to these intellectual traditions. You can be hired by other devotees of the tradition and you can be published in the journals they edit. As Upton Sinclair pointed out, “It is difficult to get a man to understand something, when his salary depends upon his not understanding it.” [Upton Sinclair, I, Candidate for Governor: And How I Got Licked (Berkeley, CA: University of California Press, 1994), p. 109.] Finally, these traditions have massive defenses in the form of the literature. Critics can be dismissed when they have not read and rebutted a great deal of theoretical bumf.
But the fact remains that a great deal of philosophical ethics is no better than theology.