Pleasure and same-sex sexual activity

1. Each kind of deeply humanly significant pleasure is a way of affectively relating to an independent deeply humanly significant kind of good in which the pleasure is taken. (Premise)
2. There is no deeply humanly significant good in same-sex sexual activity when the couple takes no pleasure in the activity. (Premise)
3. Climactic sexual pleasure is deeply humanly significant. (Premise)
4. Climactic sexual pleasure is a pleasure taken in sexual activity. (Premise)
5. If a kind P of pleasure is a way of affectively relating to an independent kind G of good, and an instance of P fails in this way to relate to an existent instance of G, then that instance is empty. (Definition)
6. It is wrong to deliberately induce an instance of a deeply humanly significant kind of pleasure when that instance is empty. (Premise)
7. If there would be no deeply humanly significant good in an activity were the activity done pleasurelessly, then the activity fails to realize an instance of an independently deeply humanly significant kind of good. (Premise)
8. Therefore, same-sex sexual activity fails to realize an instance of an independently deeply humanly significant kind of good. (By 2 and 7)
9. Therefore, taking climactic sexual pleasure in sexual activity is empty when the partners are of the same sex. (By 1, 5 and 8)
10. Therefore, climactic sexual pleasure between partners of the same sex is empty. (By 4 and 9)
11. It is wrong to deliberately induce climactic sexual pleasure between partners of the same sex. (By 3, 6 and 10)

If this argument is sound, then heterosexual sexual relations intended to induce climactic sexual pleasure are wrong when they fail to realize a deeply humanly significant independent good. What could be that independent good? Well, if it's a deliberate attempt at reproduction, then sex is wrong whenever a couple isn't trying to reproduce. But I think the the pleasure in sex is not affectively associated with a voluntary and deliberate attempt to reproduce—there is too much of the animal in the pleasure. Likewise, the couple is not simply taking pleasure in their loving relationship—they are taking pleasure in sex. (If they were taking pleasure in their loving relationship, the sexual nature of the pleasure would be unexplained, since one can have just as deeply loving non-sexual relationships, or at best explained circularly.) Rather, it is that, I think, there is a completing of a biological whole in uncontracepted heterosexual intercourse, and that is deeply humanly significant. If this completing of a biological whole is what is deeply humanly significant about heterosexual sex, then oral sex, masturbation, and the like are ruled out. Contraception may not be immediately ruled out, but is still wrong since it is contrary to integrity: the couple is acting against the biological union which constitutes the deeply humanly significant good in which the climactic pleasure is being taken.