Second Thoughts on Natural Law Ethics
Maybe third thoughts would be more accurate, as I used to be an enthusiastic defender of natural law ethics. In any case, several readers pushed back in response to the posts a few months ago (here and here) in which I broadly rejection the idea, and I’ve been considering their comments off and on since.
What I’ve concluded is that the appeal to natural law which I reject as invalid could be dubbed the derivationist variation–the idea that we can derive from a metaphysical-teleological study of human nature absolute moral norms governing human action. You cannot, for example, derive an absolute conclusion about the rightness or wrongness of contraception from factually-based conclusions you’ve reached about the natural (biological, etc.) purpose of human sexuality.
However, not all appeals to natural law argue this way. You could, for example, compose an argument that one ought or ought not use contraception based on the consequences their use has for human fulfillment, well-being, and happiness. This sort of argument would presuppose that human fulfillment, well-being, and happiness are appropriate standards by which to morally and ethically judge human conduct, but it wouldn’t fall prey to the “is-ought” problem. You’re not saying that the “natural” purpose of Y is X, therefore Y always ought be done in accordance with X. Rather, you’re saying that using Y in accordance with X brings H, and because one ought to act in ways that bring H, one ought to use Y in accordance with X.