Deposed Egyptian President Mohammed Morsi's national security adviser has described what happened there as a "military coup," and by the traditional definition of that term - "when the military or a section of the military, turns its coercive power against the apex of the state, establishes itself there, and the rest of the state takes its orders from the new regime" - this certainly seems to fit the bill.

So how then are supporters of democracy in Egypt - both the crowds in Tahrir and foreign observers - to think about these events? Traditionally, military coups are thought of as the antithesis of the democratic process - raw political power being wielded through the barrel of a gun rather than a ballot box. In fact, according to U.S. law - albeit a frequently skirted law - foreign aid cannot be provided to governments that took power in military coups. (However they respond to last week's events, don't expect Obama administration officials to be throwing around the word "coup.")

But are there cases when a coup can advance democracy? In a 2012 article for the Harvard International Law Journal, Ozan Varol, now a professor at Lewis & Clark Law School, argues that while the vast majority of military coups are undemocratic in nature and lead to less democratic political regimes, there are significant examples of "democratic coups d'etat."

If the concept seems ridiculous, consider the fact that last week Americans celebrated an armed uprising to overthrow an autocratic government. Why are bloody insurgencies sometimes considered legitimate but not actions taken by established militaries acting on behalf of disenfranchised citizens?

Varol cites three case studies: the 1960 Turkish coup in which the military overthrew the ruling Democratic Party, which had gradually consolidated political power and cracked down on political opposition and the press; the 1974 Portuguese coup, also known as the Carnation Revolution, in which the authoritarian "Estado Novo" was overthrown by the military after tanking the country's economy and embroiling it in a series of unpopular wars in its African colonies; and - interesting in this context - the 2011 ouster of Hosni Mubarak.

Varol argues that there are seven characteristics a coup must generally meet in order to be considered democratic:

(1) The coup is staged against an authoritarian or totalitarian regime; (2) the military responds to persistent popular opposition against that regime; (3) the authoritarian or totalitarian regime refuses to step down in response to the popular uprising; (4) the coup is staged by a military that is highly respected within the nation, ordinarily because of mandatory conscription; (5) the military stages the coup to overthrow the authoritarian or totalitarian regime; (6) the military facilitates free and fair elections within a short span of time; and (7) the coup ends with the transfer of power to democratically elected leaders.

So does what's happening in Egypt right now fit the bill? For the last two criteria, it remains to be seen. Two through five are arguably a good fit. But the first and most important one is a tough sell. Morsi was democratically elected just a year ago. To the extent that that election was marred by political interference, it was to the detriment of the Muslim Brotherhood.

On the other hand, Morsi's opponents would probably argue that the Brotherhood was itself engaged in what's sometimes called a self-coup, or autogolpe, in which a democratically elected government gradually erodes the country's political institutions to keep itself in power - in Morsi's case, increasing the power of the executive through a series of presidential decrees.

The military will argue that its actions were necessary to prevent the emergence of a new authoritarian strongman. The good news is that around the world, coups now more frequently result in a quick return to the normal democratic process than in the bad old days of the Cold War. But it's also possible Egypt may be in for something like the old-fashioned Turkish model in which the government was nominally democratic but the military would step in periodically to make "corrections." There's some evidence to suggest the Egyptian military has been interested in such a model since Mubarak's ouster.

The Egyptian military's actions over the next few weeks will largely determine how history views these events, and the danger of admitting the existence of "democratic coups" is that coup plotters almost always describe what they're doing as safeguarding democracy even as they accumulate power for themselves. Whether something is a "coup" or a revolution, and whether a coup is democratic, is generally in the eye of the beholder.

Joshua E. Keating is associate editor of Foreign Policy.