A cow, as depicted in the classic agricultural documentary The Simpsons.
***
Bestiality—i.e. the practice of human beings engaging in sexual activity with non-human animals—is morally wrong. I won’t bother to defend this claim here; I take it to be so obvious as to make argument unnecessary, and those who doubt the claim are probably too far gone to listen to reason anyway. If somebody seriously thinks that sex with animals might be permissible, “I do not want to argue with him; he shows a corrupt mind” (Anscombe 1958, 17). What I do want to do is explore the consequences that the wrongness of bestiality might have for our normative theorizing.
Most of us think that the consumption of animal products (including meat) is permissible under at least some circumstances. This is true even of many (such as myself) who oppose factory-farming. But this raises a puzzle: if we think that it is permissible to obtain such products, then how can we account for the wrongness of bestiality? It can’t be that the practice involves non-consensual contact with the animal’s body, for this would plausibly make it impermissible to milk cows, and would certainly make it impermissible to artificially inseminate them for the purpose of breeding (which is widely done even on smaller farms).1 It might even rule out pet ownership and the use of animals for labor; after all, they didn’t consent to those things either. The wrongness of bestiality also can’t be accounted for in terms of harm, at least if we think it is sometimes permissible to kill animals for meat. After all, even humane forms of slaughter plausibly inflict more harm on the animal than would bestiality.
So why is bestiality so obviously immoral? Here is a plausible answer: the human sexual faculty has certain natural ends—i.e. reproduction and unity with another human being—and bestiality is intrinsically incompatible with these ends. In other words, bestiality is wrong because it is perverse, in the most technical sense of that word. This seems like the most obvious answer to our dilemma; after all, if bestiality isn’t a violation of the animal’s (plausibly non-existent) rights, and if it is less harmful than activities we deem permissible, then the only way to explain its immorality is to appeal to some intrinsic characteristic of the action itself. I close by noting that if bestiality is wrong because it is a perversion of the sexual faculty, then natural law theory is almost certainly true.
Of course, one might think that the artificial insemination of farm animals is intrinsically impermissible. I myself am not sure what to think of this; still, it does not seem obviously wrong, so long as the animal is not made to suffer.