  To understand human beings and human society in terms of matter and motion, then, is simply to understand them in terms of causes and effects. Holbach’s naturalism in ethics and political theory extends to a commitment to ground those disciplines in an account of human nature understood in terms of lawlike regularities, most importantly, psychological laws. But Holbach is not a naturalist in the stricter sense of attempting to understand human beings in terms of the same laws that explain the rest of nature. Determinism is universal, in Holbach’s view, but different sorts of bodies may have peculiar properties that require peculiar explanations. Despite his avowed materialism, Holbach does not demand the sorts of reductive explanations of mental events that materialism might ordinarily seem to require. 