What do we mean by natural (When applied to the gay-debate)?

It is oftentimes argued that homosexuality is not right because it is "against nature". What does this actually mean?

1. On the other hand we can see homosexuality among animals (is it natural?)
2. On the other hand humanbeings have (biologically speaking) two different sex organs, which (If examined) function correctly only if male and female have coitus (a matter of shape & function).
In a sense this argument is more teleological or functional. Should we even call it "natural"?

1) You need to ask people who use this horrible "argument" what they mean. In my experience, most of the time they are unaware of homosexuality among non-human animals in nature.

2) If we assume that sex organs are exclusively "for" reproduction, then those who use this argument have a point about being "unnatural'. However, we know old people have sex, as do those who can't have babies or protect against having babies, and virtually 99.9% of all human sex is for reasons other than reproduction. What is "natural" is sex as a way to bond emotionally with others (same or different sex).

Let's not forget that this is based on the classic appeal to nature fallacy anyway. Even it were "unnatural," so what? Surgery, medicine, cars, etc... are all "unnatural" and we are grateful for them.

The meaning of the word natural as it appears in various online dictionaries is highly ambiguous. In part, this ambiguity (i.e., equivocation) comes from the ambiguity of the another word from which it's derived, namely: nature. In these dictionaries, nature appears to have over 15 different meanings, some of them overlapping. From the research I did, I picked a few relevant meanings:

a. "the fundamental qualities of a person or thing; identity or essential character and also: the basic character or qualities of humanity "- In this sense(s) nature refers to what is fundamental to a person/humanity and only to that person or thing. If used with this sense, "nature" and "natural" can also refer to homesexuality. So, "homosexuality" could be/is part of the person's nature and therefore cannot be wrong (if this is the meaning intended in an argument) unless the arguer assumes that human nature is somehow corrupted or rotten.

b. "tendencies, desires, or instincts governing behaviour "- When used in this sense, homosexuality, is a propensity when we take into account that there is a biological basis of homosexuality.

Other meanings of nature and natural equivocate morality with "natural" and/or "nature". Is is the task of the one who makes the argument to separate the two meanings.

1. In the senses presented above homosexuality is natural even among animals. It is a biological predisposition, and therefore what is fundamentally a part of some of the animal's "nature". Some would object that majority determines what is natural. It does not mean that if the majority of the animals do not display homosexual behavior the minority is unnatural. On the contrary. It is natural for the minority to behave in a certain way for other reasons that the majority.

2. I think you are right when saying that the second argument appeals to function when trying to support the idea that homosexuality is unnatural. I don't think we should call it "natural". But this is the case only if we assume that the sexual organs are used solely for reproduction. If the function if the sexual organs is only reproduction then it follows that homosexuality is unnatural. But is this the case? Can homosexuality and/or heterosexuality, for that matter, be reduced only to the reproductive function? I don't think so. Moreover, is does follow at all even if we accept the above premise that because it's not natural it's wrong. Morality is applied to behaviours action etc. that break certain laws/principles be the written or unwritten. What is the moral principle and/or law that homosexuality breaks?

Obviously, not everything that is natural is good (e.g., earthquakes) as not everything that is non-natural/artificial is bad (e.g., car engines). Somehow, some people manage to make a logically abhorrent mixture of "natural" and "good" or "bad" and still be comfortable with themselves. :)

I am a new, but passionate, student of 'study of logic' (philosophy?). So I am not so sure about my answer, I shall just state my view on this.

a) People who say homosexuality is against nature, I think they point to 'nature of human'. And, by that they mean that there are specific characteristics of human beings which is constant, and they know those by heart. Now the questions arise - 1) Are characteristics of human unchangeable? 2) Are those found by research, or made up, i.e. 'should be'? 3) Who conducted that research, or respectively, who created those and why?

b) There are murder, rape, dirty politics, and other crimes in other animals too. So we can't actually accept or discard just because it is or isn't in other animal species, or in our surroundings, in 'nature' (consists of forest, grass, sky, river, waterfall etc).

c) The 'mother nature' always finds a way to balance the 'harmony of nature'. So I assume, homosexuality is just 'mother nature's way to reduce the overpopulation of human race; greed and hatred, which gives birth of war, is her way to stop the destruction that human race do to her.

d) Just because our 'biological relatives' show homosexual activities among them, doesn't prove that they are emotionally attached to their homosexual sex partner, like homosexual humans. (Or do they? Any proof of a valid research?) It also doesn't prove they like it; what if they were just super horny, and no member of opposite sex was available that time? I guess other animals don't believe in masturbation. What if they engaged in homosexual activities just because they were high, or some other reasons and then regretted afterwards? What if they were manipulated or mentally forced to have coitus with other members as a display of domination, just like in rape with physical force? Is there any valid research that answers all or any number of these questions?