Abstract

The reticence of scholars of ethics to enter into fundamental moral reasoning is well known. William Casebeer’s ambitious new book, Natural Ethical Facts: Evolution, Connectionism, and Moral Cognition, which is the publication of his 2001 University of California, San Diego, Ph.D. dissertation, stands in stark contrast. Casebeer, who teaches philosophy at the U.S. Air Force Academy, has undertaken the project of developing a comprehensive moral theory derived from what he terms “methodological naturalism.” Methodological naturalism, he explains, is a system of moral reasoning derived exclusively from the empirically verifiable claims of science. His ethic starts with the materialist premise that all reality is reducible to matter and energy; since matter and energy are sufficiently explainable in terms of facts derived from the scientific method; morality too, as real—he is undeniably a moral realist—must be sufficiently explained in terms of such facts. With particular attention given to the cognitive sciences and evolutionary biology, Casebeer’s naturalism boldly asserts that ethics is reducible to science, moral norms to empirical facts, and practical judgments to theoretical propositions. This of course implicates the author in what critics refer to as the “naturalistic fallacy,” that is, the illicit inference from facts to norms. Aware of this, Casebeer attempts to show that such an inference is not only not illicit but itself the substance of fundamental moral reasoning. Unfortunately his refutation of the naturalistic fallacy is selective. He reduces the entire complex discussion to a distinction between analytic and synthetic statements, then successfully throws into doubt the existence of such a distinction and judges himself done with the whole question. Using David Hume and G. E. Moore as his principal foils, his refutation entirely ignores the most enduring and plausible argument against deriving “ought” from “is,” proposed by the great medieval philosopher Thomas Aquinas and his contemporary expositor, the Oxford philosopher John Finnis.