The young, punky Elvis Costello once claimed that his "ultimate vocation in life is to be an irritant."

Judging from some recent Facebook and Twitter comments, many of my liberal readers and friends apparently think something similar about me — at least when I write about what I call moral libertarianism.

Why, these readers wonder, do I continually highlight such trends as the acceptance of homosexuality and same-sex marriage, polyandry, the mainstreaming of porn, consensual brother-sister incest, and bestiality, while also insinuating that they're all somehow connected? In doing so, aren't I invoking the same kind of alarmist and fallacious slippery-slope arguments favored by social conservatives — and in particular by the wannabe savior and champion of the religious right Rick Santorum, who seemed to imply back in 2003 that legalizing same-sex marriage might lead to the acceptance of "man on dog" relationships?

So what's the truth? Am I really the Rick Santorum of punditry?

The answer is no, though I can see how some liberals might be led to that conclusion.

As social psychologist Jonathan Haidt has shown (and as I've written about before), liberals tend to focus on two aspects of moral experience: care for and avoidance of harm toward others, and a concern for egalitarian fairness and hostility to cheating. As for more hierarchical or aspirational moral ideals — loyalty/betrayal, authority/subversion, and sanctity/degradation — those matter much less to liberals. Conservatives, by contrast, express concern about all five moral categories, with religiously oriented conservatives placing special emphasis on striving for moral sanctity or purity.

When I write about our moral qualms (or rather, our increasing lack of moral qualms) about homosexuality, polyandry, porn, consensual brother-sister incest, and bestiality, I'm focusing on a dimension of morality that liberals are both relatively uninterested in and often positively uncomfortable with. That means that just by raising these subjects for discussion, I sound an awful lot like a conservative. The sanctity/degradation dimension, especially, reeks of traditionalist religion — and nothing makes a liberal more uneasy than a traditionalist religious believer driven by a longing for purity and lamenting the culture's collapse into sexual degradation.

But the suspicion that I'm covertly on the religious right's payroll goes beyond my mere discussion of such topics — and beyond references to my biography (which includes a multi-year stint as an editor at a magazine affiliated with the religious right). I may strive for a dispassionate tone in my writing about moral trends, but it's possible to detect a degree of discomfort as well. When I ask what my readers would do if their daughters began to work in porn, or raise the question of whether there are any legal grounds for outlawing consensual brother-sister incest, or wonder if it's okay for a human being to engage in sexual relations with a horse, I sometimes sound troubled, disturbed, agitated.

Am I?

Yes. And you know what else? I suspect that many liberals are, too, though they're loathe to admit it in public, and perhaps, in many cases, even to themselves. So some of what I write along these lines is intended to shake up my liberal readers — to get them to face their own latent, residual moral conservatism.

Is that because I want to lead a moral counter-revolution like my former colleagues on the religious right? Not at all. I want my liberal readers to face their own half-buried moral convictions because I want them to become more self-aware, more self-conscious about the profound moral shift that's going on around us at this very moment — and to see that certain of their less concealed, more explicitly and passionately held moral ideals are helping to drive the change.

Every society in human history outside of the contemporary West has upheld, inculcated, and passed on to later generations some comprehensive vision of the human good that has included a hierarchical dimension of moral judgment — very much including Haidt's final category of sanctity/degradation. Such societies have also been concerned to varying degrees about care/harm, but not to the exclusion of other moral considerations.

Only in the modern West and only within the past few decades has the concern for care/harm — with both care and harm defined exclusively in terms of individual preferences and desires — begun to drive out other moral principles. That's what I mean when I write about moral libertarianism and the elevation of individual consent into the sole justifiable measure of right and wrong. Outside of the relatively narrow sphere of the law, this shift isn't taking the form of a slide down a slippery slope, as if the acceptance of homosexuality were causing or leading to the acceptance of other sexual behaviors that were once considered deviant. Rather, the public condemnation of all such behaviors is slowly fading away because of an underlying ethical shift that has transformed care/harm into the ultimate moral trump card.

That's why the recent 6,200-word New York magazine interview with a committed "zoophile" is so important — because it's such a perfect example of this transformation and its practical implications. The piece expressed no concern about the subject's moral degradation and in fact contained no moral judgments at all — except to denounce those who would make such judgments. And why is it wrong to judge a man harshly for having sex with a horse? Simply because, the interview clearly implied, it would be mean (and so harmful) to those who have such desires.

Don't get me wrong: being nice is definitely a good thing. But is it the best thing? The highest thing? The thing that should override every other possible moral judgment? I'm not so sure — and if I'm right in my suspicions, many liberals harbor similar doubts, while also preferring not to be made to confront the inevitable moral trade-offs. My columns on these topics are designed to force them to do exactly that — to bring them around to recognizing the questionableness and possible social and cultural costs of treating niceness as the ultimate — and perhaps the only — moral good.

No wonder so many liberals find me irritating.

None of us knows the social and cultural consequences of expunging all notions of sanctity/degradation from our public life — because it's never been tried before. I think that very fact makes it worthy of serious reflection, wonder, and even worry.

Does my modest effort to inspire a modicum of ambivalence and a measure of concern about a series of sweeping social and cultural changes make me next of kin to Rick Santorum?

I suppose that's one way to look at it.

As for me, I prefer to think of it as the musings of a liberal who's troubled by certain aspects of his liberalism.