Because school has been keeping my very busy of late, I haven't been able to write as much as I had been before, but over the course of this semester I've (slowly) been attempting to address the question of whether asexuality is a sexual orientation. First, I observed that "sexual orientation" is polysemous (one word has a number of distinct, but closely related meanings), and have so far discussed asexuality in terms of scientific definitions and in terms of legal definitions. The third type of "definition" I wanted to address is that of social definition.
Here, I use quotation marks because I don't think that definitions are really appropriate for most human concepts--the categories we use work well enough for daily life but typically lack precision and defy definition. Areas such a science (where operational definitions are essential), law (where definitions are crucial), and mathematics (where precise definitions are actually possible) seem to be the exceptions, not the rule. Definitions are, at best, useful rubrics, signposts helping beginners to understand, roughly, what something means; and they may be helpful in thinking clearly about some issue and they can be ideological battlegrounds.
For "sexual orientation" as a social concept, I will avoid definitions for another reason: lots of people have very different ideas about what sexual orientation is and few use precise definitions. And most who use definitions only do so to try to explain some idea they already had.
So, with our vague and undefined notion of "sexual orientation" as it exists in various people's understanding, is asexuality a sexual orientation? Well, it depends on who you ask. Some people say it is. Some people say it isn't. Most people have no idea what asexuality is and have probably never considered the matter. Most who have considered the matter have probably not considered it at length.
Nevertheless, current ideas about sexual orientation are generally that most people are straight and some people are gay (and, if pressed, I imagine that most people acknowledge that some people are bi. Taking this as a general starting place (because it is a general starting place for most people), there seem to be basically three options for conceptualizing asexuality:
1) Asexuality is a sexual orientation.
2) Asexuality is a lack of sexual orientation.
3) "Asexuality" is a sexual dysfunction.
I think that it is very difficult to figure out what empirical differences there are between these. It is, in my view, principally a value judgment, and the main basis on which decisions will be made regards what people feel makes most sense, and what people feel will be most helpful for such individuals. Thus, it seems that perhaps we should rephrase the question: Rather than asking the question in the title of this post, perhaps we should ask, "Socially, should asexuality be considered a sexual orientation?"
Now, in media presentations of asexuality (and in academic ones) there is a rather interesting phenomenon that I've never seen explicitly discussed, though I imagine many engaging in it are well aware of what they're doing. The question of whether it would be most beneficial to asexuals if, socially, asexuality were considered a sexual orientation is a matter separate from the scientific issues involved in deciding whether it makes sense scientifically to regard asexuality as a sexual orientation. There is no a priori reason why the two questions must have the same answer.
In media presentations, there are often academics--taking various positions--using their perceived status as experts to advance their own positions on whether asexuality is a sexual orientation. Of course, many of these people may well be experts in some areas of human sexuality, but some of them have never actually studied asexuality but don't feel that this disqualifies them from using their expert position to advance their own ideology. (And those who have studied asexuality, tend to be supportive of the position that asexuality is a sexual orientation, but also tend to make very guarded claims, noting that very little is known at this point.)
Still, because of the respect granted to science in society at large (though, this is often not nearly as much respect as scientists would like), it is recognized that if scientific evidence can be given which is used to justify the claim that asexuality is a sexual orientation, this is felt to add legitimacy to accepting asexuality as a sexual orientation in terms of vaguely defined understood social categories. To a large extent, regarding asexuality as a sexual orientation (scientifically) adds legitimacy to regarding asexuality as a sexual orientation (social "definition") precisely because people rarely stop to think about how these are different matters.
To a large degree, it is because people think of the question in terms of "Is asexuality a sexual orientation?" rather than "Should asexuality be regarded as a sexual orientation?"