(c) 2013, Bloomberg News.

(c) 2013, Bloomberg News.

The following editorial appears on Bloomberg View:

How much importance should the world attach to Iranian President Hassan Rouhani's acknowledgment that the Holocaust happened and was "reprehensible"? In two words: a lot. Or four: but not too much.

When former Iranian President Mahmoud Ahmadinejad denied the Holocaust, he was justifiably condemned. That his successor has resiled from such delusional hostility is noteworthy. At the same time and much as it would be nice if it did the acceptance of a well-settled historical fact doesn't qualify as a diplomatic breakthrough.

There are (at least) two contexts in which to view Rouhani's statement. The first is in the context of present-day Iran, whose leaders have repeatedly called for the destruction of Israel and are pursuing a nuclear program that could give them the means to accomplish their goal. When Ahmadinejad dismissed the murder of 6 million Jews, it indicated a chillingly casual attitude toward genocide.

Rouhani's correction is a small but significant step, though diminished by the insistence of the semi-official Iranian news agency Fars that, in his interview with CNN's Christiane Amanpour, he never used the words "reprehensible" or "Holocaust." Nonetheless, his meaning was clear enough: "As to the massacre of Jews by Nazis, we condemn it completely," he said just hours earlier in an interview with reporters from Bloomberg News and elsewhere.

Left unaddressed is Rouhani's position on Israel. Other Iranian leaders, and not just Ahmadinejad, have been clear. In recent decades, Iranian political, military and religious leaders, among them the supreme leader, Ayatollah Ali Khamenei, have said Israel must be "destroyed," "annihilated" and "cut off." Officials have occasionally clarified that they are referring to the state of Israel, not its people. This is hardly comforting.

Which brings us to the other context in which to view Rouhani's remark: through the history of anti-Semitism. More than simply a prejudice, it is a defective world view, one particularly ill-suited to the stresses of openness or the demands of diplomacy. "The anti-Semite fails to grasp how the world works," writes Walter Russell Mead, "and that failure condemns him to endless frustration."

Frustrating is certainly an apt term for the U.S. and the world's negotiations thus far with Iran over its nuclear program. In that sense, two other aspects of Rouhani's CNN interview, overlooked amid the controversy over his views on the Holocaust, were encouraging.

The first is his reiteration that he is authorized to negotiate with the U.S. and its allies over Iran's nuclear program. Khamenei may well just be giving Rouhani enough rope to hang himself, or it could all be a game of shells. But without such a license, little is possible.

So it was a little surprising to hear Rouhani describe his mandate in broad democratic terms. In June, he defeated Khamenei's favored candidate by pledging to negotiate an end to sanctions that are crippling Iran's economy. It is "the will of the people of Iran," he told Amanpour, "to create a new era of relations between the people of Iran and the rest of the world."

Rouhani's nod to the importance of popular legitimacy especially if he sees it only as a way to help him fend off opponents in the Khamenei regime doesn't make him a friend of the U.S., or of Israel, or even a reformer. Along with his acknowledgment of the Holocaust, however, it is another hopeful sign that he is someone with whom the rest of the world can try to do business.