The government Iran has had since 1979 is a strange hybrid of democracy and theocracy. As such, it is a an experiment in whether such hybrids can ever work. Many people around the world are interested in systems that would have a democratic component but which would also somehow protect core principles from the popular whim. The authors of our constitution wanted to at least slow down the forces of popular rule, with institutions such as the Senate and the Supreme court that are designed to change slowly. But the system is at its root democratic, and in the long run the people will have their way.
In Iran, the notion that the state should be Islamic first and democratic second has wide support. But what does that mean? Who decides what stands on contemporary issues are Islamic? The Iranian system includes committees of Islamic scholars with names like the Council of Guardians that are supposed to speak for Islam in a way removed from mere politics.
What is happening in Iran now is that the Iranian people are unhappy with the way certain forces within the clerical establishment have interfered with their democratic will. Those clerics -- who, depending on the context, are called both "conservative" and "radical", which shows that our categories don't fit them very well -- have fought for a program of tighter social control at home, a strong military (including nuclear weapons), and strong positions against Israel and the US. They have used the powers granted to them under the hybrid constitution to stifle opposing voices who have tried to compete in the democratic part of the government. They have also acted corruptly, using oil money to build up a network of companies and militias under their control.
Now it seems that the clerics have used their control of the electoral apparatus to steal an election. If true, this marks a real change in their behavior, and a flouting of the constitution that gives them their legitimacy. I am not clear on why they would have done this. The powers granted them under the constitution are great, and allowed them to thwart previous reform presidents. It seems that they have simply gotten impatient with the whole business of holding elections and taking the popular will into account at all.
The people are, understandably, outraged.
I suspect that the "revolution" will be defeated, and that the clerics will hold onto power. If they do fall, it will be because they fell out among themselves, because they control most of the real levers of power in Iran, including the army, the militias and the press.
More broadly, I think the violence in Iran is bad news for all the would-be builders of partly democratic systems. Either the people are sovereign, or they are not. They may accept partial power for a while, but in the end I think all such systems will face a crisis like Iran's, in which the people will come into conflict with the other powers, and one or the other will be defeated.
One of Andrew Sullivan's readers sent in this observation: "Leading the populace to believe that its opinion matters is extraordinarily dangerous for a regime that has no intention of listening."