The fight over same-sex marriage raises many polarizing issues and provokes passionate denunciations on all sides. Among the most common is the claim by those who support gay marriage that all those who oppose it, no matter their reasons, are motivated by anti-gay bigotry.

I've rejected that argument on numerous occasions. One may hold for religious or other reasons, and without denigrating men and women who experience and act on homosexual desires, that marriage is an institution properly oriented toward procreation and therefore permanently closed to homosexual couples. This isn't my view; I strongly support gay marriage. But those who take a different position aren't moral monsters worthy of condemnation. They are fellow citizens attempting to uphold a traditional view of the family and its social purposes that is no longer universally affirmed, but is still perfectly legitimate.

And then there are those who really are anti-gay bigots. You'll still hear them in bars and frat houses, on playgrounds and ballfields around the country, spewing hateful venom at "f--gots" and "d-kes." In most cases, their views are a product of ignorance and unexamined prejudice.

But what about those who should know better?

Ladies and gentlemen, I give you Harry Jaffa — esteemed student of political philosopher Leo Strauss, leading conservative scholar and intellectual, author of a justly admired study of the Lincoln-Douglas debates, object of veneration on the right since his death on Jan. 10 at the age of 96, and (as Nathan Robinson at Salon has helpfully brought to our attention) an unreconstructed anti-gay bigot.

Much of it is laid out, clear as day, in Robinson's essay: How Jaffa consistently referred to homosexuals as “sodomites.” (The most recent published example appears to be this 2004 interview.) How he composed a preposterous faux-Platonic dialogue between serial killer Ted Bundy and a would-be female victim in which Bundy explained how rape and murder had become acceptable because “sodomy is no longer regarded as a crime, or even as immoral.” How in a 1988 review of Allan Bloom's Closing of the American Mind Jaffa proclaimed AIDS a form of “retribution” for the “public movement to adopt sodomy and lesbianism as a recommended lifestyle.” (What Robinson doesn't note is that Bloom himself was gay and died four years later of AIDS — and that the main focus of Jaffa's critical review was the “surprising omission” of a denunciation of homosexuality from Bloom's bestselling jeremiad.)

It's nasty stuff. But is it bigotry?

Without question.

To see why, we need to delve into Jaffa's arguments against homosexuality — how he went about trying to substantiate the uncommonly extreme view that the public acceptance of homosexuality constituted “the most radical and sinister challenge, not merely to sexual morality, but to all morality.”

Although Jaffa sometimes made passing reference to God, his arguments about morality were almost invariably based on an appeal to “nature.”

Those who attempt to base morality on nature typically understand the concept in one of two ways. The first option is simply to describe what human beings do — how they behave — “by nature.” The obvious problem, though, is that human beings behave in an astonishingly wide range of ways. The deer walking through my backyard in suburban Philadelphia in 2015 behaves pretty much the same as any other deer in North America, South America, Asia, or Africa — today or a thousand years ago. But human beings? We differ radically from time to time and place to place. Our nature appears to be radically fluid. That's because it is always deeply intertwined with and covered over by a complex web of conventions, habits, and customs.

And yet, homosexuals have existed within every known human culture (even when the culture has singled them out for opprobrium), just as homosexual behavior has been observed in a large number of animal species. It seems that “by nature,” in this sense at least, homosexuality is a perfectly normal human behavior and not at all the abomination Jaffa thought it was.

But Jaffa seems to have meant “nature” in a second sense — one that amounts to a judgment about what constitutes human flourishing. This is a teleological notion that invokes species-specific ends or purposes. Nature in this sense is a standard one can achieve or fall short of. One can act in accordance with this nature or contrary to this nature. Behavior that accords with our nature is good for us in a comprehensive sense, and leads to happiness (in the sense of fulfillment), while behavior that is contrary to our nature is just as comprehensively bad for us.

It is this second sense of nature that we invoke when we condemn certain behavior — incest, say, or cannibalism — as “unnatural.” We obviously don't mean that such behavior is unnatural in the first, merely descriptive sense of the term, since some human beings obviously do practice incest and cannibalism. Indeed, it is this very fact that inspires us to articulate a vision of natural human flourishing that precludes such behavior.

The trouble with all moral systems based on a natural standard, however, is that it's notoriously difficult to determine what is truly good for us in this comprehensive sense. Traditions, customs, habits, and divine revelations provide numerous answers. But they also contradict each other, requiring thoughtful human beings to do the hard work of figuring out which of them, or some other option, is truly natural — the most truly fulfilling of our truest natural desires.

According to Jaffa's teacher Leo Strauss, philosophy is what enables us to settle the matter, though it does so in a paradoxical way — by helping us to see that the best way of life by nature is one devoted to the open-ended pursuit of an answer to that very question. In other words, philosophy — the never-fully-completed pursuit of comprehensive wisdom about nature (including human nature) — is itself the best way of life.

Harry Jaffa ended up embracing a very different vision. At least when it came to matters of sexuality, he proved himself to be impatient with questions, irritated with philosophy. He wanted answers, now — the kind of comprehensive knowledge that traditions, customs, habits, and divine revelations claim to provide. But he wanted to be able to call this knowledge “nature,” and he wanted nature to support his all too typical (for a 20th-century conservative American male) attachment to monogamous heterosexual marriage and procreative copulation. Everything else would be comfortingly (and cruelly) condemned as “sodomy.”

There are too many problems with Jaffa's vision — according to which “the very idea of a moral obligation” depends on “the framework of human experience where two human individuals are responsible for the conception of a third” — to list them all here. I'll stick with one that grows out of what we've seen so far about normative standards of nature: What about people who do not sense themselves to be flourishing in a life of procreative copulation? May they ever engage in non-procreative sex acts? Or is contraception allowed? And if it is allowed, then why not other forms of non-procreative sex, like oral sex or anal sex? And how about masturbation — either a couple masturbating together in a state of mutual sexual arousal and intimacy, or each partner masturbating separately, or a non-married individual masturbating alone as a harmless form of sexual release? Are any of these non-procreative sexual acts morally permissible? Are any of them compatible with human flourishing?

I ask these questions because all of these forms of sexual activity — and not just anal sex between homosexual partners — were once condemned as sodomy. Andrew Sullivan pointed this out in an indispensable 2003 article for The New Republic that originally, and aptly, ran under the headline, “We're All Sodomites Now.” By “all,” Sullivan meant everyone who engages in any form of sexual activity besides non-contraceptive heterosexual vaginal intercourse. That, I would maintain, is just about everyone in America in 2015.

Was it Harry Jaffa's view that virtually all post-pubescent Americans are thereby living lives contrary to human nature? Defying our own good? And in the process rendering it impossible to make even the most elementary moral judgments, about rape and murder?

Not to put too fine a point on it, but that is a ridiculous thing to believe.

The Supreme Court has suggested that bigotry be defined as “irrational animus.” That strikes me as a definition as good as any. And by that definition, Harry Jaffa, whatever his worthwhile contributions in other areas of thinking, was an anti-gay bigot. His undeniable animus against homosexuals was not based (at least consciously) on traditional, customary, habitual, or revelatory strictures, which can have their own dignity. He claimed it was based, instead, on “nature.” But that was a self-justificatory fiction. It was an attempt on Jaffa's part to transform a reaction of disgust — “ew, the things those men do together is so gross” — into something nobler and more respectable.

The effort failed.