(Atta Kenare/AFP/Getty Images)

At a White House press conference Thursday, as Sen. Chuck Hagel's confirmation hearing raged in the Senate, a reporter asked a deceptively simple question: "Does the president believe the government of Iran is legitimate and elected?" Hagel had, controversially, said at the hearing that it was, though he conceded the widespread reports of fraud in their 2009 election.

White House spokesperson Jay Carney sidestepped the question, which had to be asked a second and a third time before he finally said, "Look, it’s the government that we deal with, and it is the government that continues to flout its international obligations, and that behavior is illegitimate." In other words, he wasn't willing to say whether or not the U.S. considers the Iranian government to be legitimate.

The refusal to engage the question was, no doubt, in large part for political reasons; either answer is a loser. If Carney called Tehran illegitimate, he would seriously undermine any efforts at diplomatic engagement with Iran; you can't make deals with a government you feel has no legitimate authority to accept them. If he had called it legitimate, he would have invited backlash from within Washington and angry questions about why he was propping up a despotic regime that is not exactly a friend of America.

But there's another reason that the White House is probably not eager to make any public stands on the legitimacy of the Iranian government: it would beg the obvious follow-up question, why or why not? And, even worse, it would invite world leaders to consider what other government did or did not meet Obama's standard of legitimacy.

The truth is that the question of what makes a government legitimate is a notoriously complicated one. The Universal Declaration on Human Rights, adopted in 1948 by the United Nations with strong U.S. support, declared, "The will of the people shall be the basis of the authority of government." That's another way of phrasing a political theory called "the consent of the governed," which says that governments get their legitimacy from a willfully governed populace and which was championed by 17th century English philosopher John Locke. Locke's ideas, particularly about political legitimacy, helped provide an ideological foundation for the American revolution.

Our world is a little more complicated today, with a number of regimes such as Iran's, authoritarian in its grip on power but also earnestly supported by some number of citizens. Are they legitimate? Where is the line between a government that rules through force rather than consent and one that has consent but is not actually democratic? Is there such a thing at all, or does a government require democratic institutions through which to acquire consent?

"Despite the acknowledged importance of legitimacy, political science remains divided about its meaning and its sources," Bruce Gilley, of Princeton University, wrote in a 2006 paper for the European Journal of Political Research. "As a result, there is no existing cross-national data set on the legitimacy of states, much less an agreed way of creating one."

In other words, there is no list of legitimate and illegitimate governments because, as Gilley shows, it is not a simple binary. Rather, he defines legitimacy as a question of degrees. "A state is more legitimate the more that it is treated by its citizens as rightfully holding and exercising political power," he writes. So, yes, Norway is more legitimate than North Korea. But if you're looking for the thin line that divides the legitimate governments from the illegitimate, you're not going to find it.

Earlier scholars have argued that there are three ways that an individual citizen can shed legitimacy on his or her government, whether knowingly or not: through views of legality, views of justification and acts of consent. Democracy, of course, tends to fulfill all three. But perhaps you can see ways here that other forms of government, even if in practice they are headed by people we don't like and tend to do some very bad things, can still pick up some legitimacy. Presumably, some number of people in Iran, not all of them, believe that the government's crackdowns in 2009 were justified to maintain order. Or maybe they hate the government but, to get through the week, they still go to their civil service job. That doesn't make Supreme Leader Ali Khamenei legitimate in a categorical sense, but it does offer him some degrees of legitimacy.

In his 2006 study, Gilley attempted to actually quantify and rank the legitimacy of 72 different national governments using a number of statistical metrics. Iran ranked near the middle, at 44, above countries like Croatia, Mexico and even India. A lot has changed since 2006 and his metrics would presumably drop Iran several places. But don't expect any White House questions on whether Obama sees India's government as legitimate.