Dre, if you disagree with Social Contract Theory, why are all of your counter-examples (things like drugs, pedophilia, murder, etc) things that would be considered harmful within Social Contract Theory?
In all of these cases, the end result is that someone was harmed. Drugs are harmful. Pedophilia is harmful. Murder is harmful.
There's no true physical or emotional harm in homosexuality, even pre-Enlightenment except within a religious construct. Male humans have the advantage of being more frequently engaged in sexual activities or thought; this increases the odds of procreation, but this is simply an evolutionary advantage. It exists not for any reason, but humans procreate more often because we have this advantage. There's no causation to prove homosexuality exists outside a "natural" framework. Our drive and psychological need for sexual contact doesn't discriminate, or rather, there's no real proof that it does.
Also, while you are correct in that many of the posters in this thread are assuming Social Contract Theory, you are assuming something else pretty important, which is that in the "natural" world, sex is reserved for procreation, which isn't and can never be proven.
I wonder why you aren't offering any other examples that would be, within modern times, considered "wrong" even though they don't harm our existing construct or another person. Is that because homosexuality is the only one? Is it the only one because you sought justification for your argument after you decided you were against homosexuality?
If you want to assume a neutral position, you could start by assuming that sex is neutral, which as far as we know, it is.
Social Contract Theory is so prevalent
because we cannot create a logical basis for anything without it. Natural law doesn't really exist; we have no one to answer our questions about it, and no authority over it. In nature, the fittest survive, and that is the only "rule." Your "natural" approach to social constructs doesn't really work, because it makes a lot of assumptions about nature and ecology. Social Contract doesn't make any assumptions, it just asks you to keep your hands to yourself. A true "naturist" approach would look like anarchy or chaos.
To challenge the statement "homosexuality is as legitimately acceptable as heterosexuality", you'd have to first remove the social contract.
Even removing the social contract isn't enough, unless you're using a religious contract instead. But that's just another contract, isn't it?
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)