WASHINGTON -- There are two ways to defend gay marriage. Argument A is empathy: One is influenced by gay friends in committed relationships yearning for the fulfillment and acceptance that marriage conveys upon heterosexuals. That’s essentially the case President Obama made when he first announced his change of views.

No talk about rights, just human fellow feeling. Such an argument is attractive because it can be compelling without being compulsory. Many people, feeling the weight of this longing among their gay friends, are willing to redefine marriage for the sake of simple human sympathy.

At the same time, however, one can sympathize with others who feel great trepidation at the radical transformation of the most fundamental of social institutions, one that, until yesterday, was heterosexual in all societies in all places at all times.

The empathy argument both encourages mutual respect in the debate and lends itself to a political program of gradualism. State by state, let community norms and moral sensibilities prevail. Indeed, that is Obama’s stated position.

Such pluralism allows for the kind of “stable settlement of the issue” that Ruth Bader Ginsburg once lamented had been “halted” by Roe v. Wade regarding abortion, an issue as morally charged and politically unbridgeable as gay marriage.

Argument B is more uncompromising: You have the right to marry anyone, regardless of gender. The right to “marriage equality” is today’s civil rights, voting rights and women’s rights — and just as inviolable.

Argument B has extremely powerful implications. First, if same-sex marriage is a right, then there is no possible justification for letting states decide for themselves. How can you countenance even one state outlawing a fundamental right? Indeed, half a century ago, states’ rights was the cry of those committed to continued segregation and discrimination.

Second, if marriage equality is a civil right, then denying it on the basis of (innately felt) sexual orientation is, like discrimination on the basis of skin color, simple bigotry. California’s Proposition 8 was overturned by a 9th Circuit panel on the grounds that the referendum, reaffirming marriage as between a man and woman, was nothing but an expression of bias — “serves no purpose — other than to lessen the status and human dignity of gays and lesbians.”

Pretty strong stuff. Which is why it was so surprising that Obama, after first advancing Argument A, went on five days later to adopt Argument B, calling gay marriage a great example of “expand(ing) rights” and today’s successor to civil rights, voting rights, women’s rights and workers’ rights.

Problem is: It’s a howling contradiction to leave up to the states an issue Obama now says is a right. And beyond being intellectually untenable, Obama’s embrace of the more hard-line “rights” argument compels him logically to see believers in traditional marriage as purveyors of bigotry. Not a good place for a president to be in an evenly divided national debate that requires both sides to offer each other a modicum of respect.

No wonder that Obama has been trying to get away from the issue as quickly as possible. It’s not just the New York Times poll showing his new position to be a net loser. It’s that he is too intelligent not to realize he’s embraced a logical contradiction.

Moreover, there is the problem of the obvious cynicism of his conversion. Two-thirds of Americans see his “evolution” as a matter not of principle but of politics. In fact, the change is not at all an evolution — a teleological term cleverly chosen to suggest movement toward a higher state of being — given that Obama came out for gay marriage 16 years ago. And then flip-flopped.

He was pro when running for the Illinois Legislature from ultra-liberal Hyde Park. He became anti when running eight years later for U.S. senator and had to appeal to a decidedly more conservative statewide constituency. And now he’s pro again.

When a Republican engages in such finger-to-the-wind political calculation (on abortion, for example), he’s condemned as a flip-flopper. When a liberal goes through a similar gyration, he’s said to have “evolved” into some more highly realized creature, deserving of a halo on the cover of a national newsmagazine.

Notwithstanding a comically fawning press, Obama knows he has boxed himself in. His “rights” argument compels him to nationalize same-sex marriage and sharpen hostility to proponents of traditional marriage — a place he is loath to go.

True, he was rushed into it by his loquacious vice president. But surely he could have thought this through.

Charles Krauthammer is a colum-nist with the Washington Post Writers Group.