The appeal to nature as a criterion (or the criterion) of value is an ancient habit of our culture whose continuing popularity has irritated me for most of my life. It is in Aristotle and the canon law and the Declaration of Independence and the advertisements for shampoo. Some years ago I looked up "nature" in a philosophical dictionary & was steered to a wonderful book (Primitivism and Related Ideas in Antiquity, by Arthur O. Lovejoy & George Boas), whose appendix listed 66 overlapping & conflicting definitions of "nature", most of them commendatory and almost all of them, it seemed to me, silly. The one that makes the most sense to me is No. 17: Nature is the exterior of artifice. To say that metallic aluminum is not found in nature, but metallic gold is, is to say that if I find a piece of aluminum in a stream bed, someone put it there; if I find a piece of gold, perhaps not. That is a useful notion, but it has no more moral content than "outdoors".
Here I mean to say, in the plainest possible language, why the rest is all shampoo to me.