Because I write to a skeptical and pro-science audience, I can be reasonably sure that most of my readers consider themselves sex-positive. That is, most of you believe that sex is a good thing, as long as all parties give informed consent, and no one is harmed. You probably think that abstinence-only education is ineffective, that porn can be positive, that premarital sex is a good thing. You also probably believe that abortion should be legal, same-sex marriage should be legal, and perhaps even prostitution should be legal.
I consider myself sex-positive too. I think that the best basis for a sexual ethic is informed consent and harm reduction. Tradition is frequently wrong. Purity is meaningless. Gross-out reactions are not a moral compass. God's intentions don't exist.
But "sex-positive" isn't consistently defined in any particular way, so many people use it to mean different things. Many people also interpret sex-positive attitude as, "Sex! Rah rah rah! Everyone should have more of it because clearly that's what everyone wants."
"Everyone wants sex" isn't necessarily meant as a universal rule. For example, no one thinks that rape victims wanted to be raped. Indeed, the idea that "she was asking for it" is a repugnant myth fought by many who consider themselves sex-positive. And yet, some people universalize the rule more than they should.
That people take "sex-positive" too far becomes clear the moment you step in the asexual community. When you're asexual, coming out to people is a crapshoot. Even liberal-minded people can have negative reactions. Those liberal-minded people are usually sex-positive, and some sex-positive people just can't process asexuality. What do you mean you don't want sex? You must be attracted to someone, we just need to find who. Were you abused as a child? Do you have hormonal problems? Did you just have a bad relationship? It's okay if you're gay, so why don't you just come out already? You're repressing yourself. You've bought into a puritanical culture.
Why do people bring up all these objections? It's not because they've seriously considered each one (as asexuals have). It's because the idea that everyone wants sex is embedded too deeply in their heads, and anything that might dredge it up just bounces off.
Oh, there's more. Sex-positive people are always fighting norms against sex. They fight the idea that women are "sluts" while men are "pimps". They fight the idea that premarital sex is dirty, that virgins are pure, that fetishes are freakish, that same-sex sex is unnatural. But they sometimes replace it with the opposite norm, that everyone should have sex. It's not a frequent thing, but frequent enough to be a problem. When asexuals first enter the forums all insecure because they've felt broken and abnormal all they're lives, then we have a problem. When some depressed asexuals declare that they must lose their virginity so that they will no longer face shame for being a virgin, then we clearly have a problem.
And you know what? This isn't even about asexuality, or sexual orientation at all. It doesn't matter that I only consider myself borderline asexual. If there were no such thing as asexuality, this would still be a problem, it's just that we would have a harder time recognizing it as such. The bottom line is that people have different levels of interest in sex, different kinds of interest in sex. We need not deny it or treat it normatively.
Some people will react by saying, "those people aren't really sex-positive." But I don't care about that. I care about the people and norms that piss me off, I don't care what you call them.
Let's consider a specific issue: celibacy. In the standard asexual presentation, celibacy is contrasted with asexuality, because asexuality is an orientation while celibacy is a choice. I have made this contrast too, though I prefer to frame it as a difference between desire and behavior, rather than orientation vs choice. In general, a behavior can be non-chosen, as is the case for involuntary celibates.
There is a pretty good reason that asexual rhetoric tends to distance itself from celibacy. It's because the main audience of this rhetoric is sex-positive. Sex-positive people tend to associate celibacy with bad things like clerical celibacy and abstinence-only education. But they have it wrong. Celibacy is not intrinsically good or bad. Celibates are not unnatural, and not necessarily repressed. It can be an entirely respectable decision, one that's available to people of all orientations I might add.
To accept asexuality and reject celibacy is a little like accepting gay people but rejecting gay sex (as the Catholic Church does). It can hardly be considered proper acceptance at all.
That's not to say that we can't criticize clerical celibacy, which is a more specific kind of celibacy. If celibacy is part of a religious vow, then the vow becomes the primary consideration, and the specifics of the individual are secondary. It should be the other way around. Furthermore, requiring all leaders to be celibate implicitly places undue value on celibacy. Also, if these leaders want to talk about sexual moral values, they're going to have a very narrow perspective. Finally, I am skeptical about the idea of sublimating sexual energy into other kinds of energy. That just has pseudoscience written all over it.
But I cannot criticize clerical celibacy by declaring that celibacy in general is bad. In general, celibacy passes the test of informed consent and harm reduction. That's all we need ask for.
(Some influence for this post comes from Asexual Explorations)