I personally find teleological arguments about sex compelling – the sort of arguments that identify the purposes of the sexual powers (procreation and the union of the procreative partners), and then draw the inference that we should behave in ways that cooperate with these purposes instead of, as you say, undermining them. On the other hand, so many people seem to be able to wave such arguments away. So do you think the arguments are really strong?
I do think consider teleological arguments strong – both valid and compelling. The significance of the fact that many people refuse to take them seriously is psychological, not logical. If they refused to take them seriously because there were actually something wrong with them, I would worry. But there seems to be nothing wrong with them. The problem lies in not wanting to be persuaded.
I am reminded of a student some years ago who had just heard an explanation of what counts as a valid argument. He asked, “But what if the premises are true and the reasoning is sound, but I just know the conclusion is wrong?” I answered, “Then you change your mind.”
Well, other arguments about sexuality are available. Then should you give up on this one and only use them? That would be silly; after all, people irrationally reject the other arguments too! Besides, even when the barrier to accepting a teleological argument does lie in the will rather than in the intellect, often something can be done to get past a person’s defenses and render the argument accessible to his mind.