There’s a reason why the Nobel Peace Prize so often sets off heated political arguments: It’s conferred by politicians.

All the other Nobel prizes are awarded by scholars: The Royal Swedish Academy of Sciences, for example, chooses the laureates in physics, chemistry, and economics. The Karolinska Institute, a medical university, names the recipients of the prize for medicine. But for reasons that have never been clear, Alfred Nobel specified in his will that the peace prize should go to someone selected by a committee of Norwegian parliamentarians. And politicians in Norway, like politicians in most places, are apt to care much more about their short-term impact than their long-term credibility.

President Obama is obviously not being awarded the Nobel Peace Prize for anything he has done. After all, the deadline for nominations was February 1 – just 10 days after Obama took office. But the point of the peace prize isn’t concrete achievements in the past, it’s the effect the award can have in the present. The chairman of the Norwegian Nobel Committee, explaining the decision to honor Obama, told skeptical journalists this morning: “We hope this can contribute a little bit to enhance what he is trying to do.” When former President Jimmy Carter was given the prize in 2002, the Nobel judges readily agreed that the award was intended to be a “kick in the leg” to the Bush administration, which was then gearing up for war in Iraq.

By contrast, the science laureates are always honored for work the significance of which is well-established – work that in many cases took places decades earlier. Ada Yonath, one of this year’s Nobel laureates in chemistry, was chosen because of her pioneering investigation of ribosomes in the 1970s and 1980s. Physicists Charles Kao, Willard Boyle, and Charles E. Smith are sharing this year’s Nobel in physics for breakthroughs in the science of fiber optics and digital photography that got their start in the late 1960s. The three recipients of the 2009 prize in medicine – Jack Szostak, Carol Greider and Elizabeth Blackburn – are being hailed for discoveries in the field of cell biology that they made 20 years ago.

Nine months into the Obama presidency, as Commentary magazine’s Jonathan Tobin notes, “peace is further off in the Middle East, a nuclear Iran is a virtual certainty, and victory in Afghanistan over the Taliban is more doubtful than ever.” The closest Obama has come to playing the peacemaker was the “beer summit” he hosted at the White House in July. Someday, perhaps, he will accomplish something genuinely deserving of an international peace prize. Luckily for him, the Norwegian politicians who confer the Nobel are considerably more interested in headlines today than in genuine accomplishments “someday.”

“Awarding a peace prize,” former Norwegian Nobel Committee Chairman Francis Sejersted once said, “is, to put it bluntly, a political act.” As the award to Obama makes clear, that hasn’t changed.