We’ve seen a number of regimes fall because of popular protests: Serbia, Ukraine, Georgia, yadda yadda. We’ve also seen several that have not fallen: Burma, Armenia, Greece. Which one does Iran more resemble? Or, to put it another way, what are the common factors?
Here’s a first attempt at classification. Political scientists and (especially) people who know more about Iran are encouraged to chime in.
Factors that make a regime vulnerable
In ascending order:
1) The regime is widely hated. Surprisingly, this seems not to be a highly correlated variable. Some of the survivor regimes were almost universally loathed by their people (Burma) while some governments that still enjoyed some popular support managed to collapse anyway (Ukraine).
Relevance to Iran: Low. Many people dislike the current government, but not many actually hate it.
2) The regime is seen as compromised by association with an unpopular foreign power, hostility to religion, gross corruption, or too-obvious links to organized crime.
Relevance to Iran: Moderate. (But note that both sides are energetically trying to associate the other with foreign powers.)
3) The regime is perceived as incompetent. People seem to be much more willing to protest against a government that’s seen as a bunch of screwups, and those protests seem more likely to succeed. The correlation here is very high: of the governments that have fallen to street protests, almost all were vulnerable on this point. In some cases — Serbia, Romania, Albania, Georgia, the Philippines — the government’s incompetence was such as to obviously endanger the nation, giving the protests an immediate boost of nationalist legitimacy. On the other hand, governments that are seen as corrupt and evil, but competent — Armenia, China — are much less likely to be targeted, and much more likely to survive if they are
Relevance to Iran: Moderate. The economy has been sagging, but not enough to make everyone see the government as a bunch of idiots.
Factors that make a regime difficult to overthrow
In ascending order:
1) The regime is perceived as legitimate. Note that “legitimacy” is a slippery term. Note also “perceived as”. Stealing an election, by itself, does not seem to be enough to topple an otherwise strong regime.
Relevance to Iran: Moderate. Everyone acknowledges the legitimacy of the Islamic Revolution. Government control of the media means that much of the population — possibly a majority — do not see the election as stolen.
2) The regime has strong external support. “Strong” here means willing to intervene directly with military assistance. American support for the Shah was not strong; Soviet support for the Eastern European governments was, until it wasn’t.
Relevance to Iran: None. One way or the other, Iran will settle this by itself.
3) The regime is willing to use high levels of force against the protestors. Most of the successful overthrows have seen a loss of nerve by the government at some point. Most of the failed ones have failed because the government has doubled down.
Relevance to Iran: High. Does anyone think Ahmadinejad and his supporters are going to go peacefully?
4) The regime is able to use high levels of force. To put it another way, the security forces stay loyal to the government and obey their orders.
If we combine this with the last factor, we see there are three possible scenarios. First, the government may be willing to use force, but not able: the security forces are neutral or hostile, and will not act against the protestors. This was the situation in Serbia, Albania, Romania, and the Philippines. All those governments fell.
(There are some fine details here. For instance, in Romania, the Securitate secret police were willing to support Ceausescu to the bitter end, and killed a great many protestors. But the Army and the police were hostile, and in the end the Securitate were too few to prevail. In East Germany, Honecker was willing to use force, but the Politiburo lost its nerve and deposed him in favor of the less hardline Egon Krenz.)
Second, the government may be able to use force, but not willing. This is a slightly blurry category, because often a government is willing to use a certain level of force — Albania, Indonesia, the Gorbachev-era Soviet Union — but is not willing to order mass slaughter or the imposition of a totalitarian police state. Still, this too is a high-risk category.
And finally, the government is both willing and able to use massive force: China, Burma, Armenia. In these cases, the government wins. There is, in recent history, not a single clear counterexample. If the government keeps its nerve, and the men with guns stay loyal, and the regime is willing to escalate without limit — the government wins.
Relevance to Iran: Looks pretty high right now. While there are some reports of unease among the security forces, it appears the police and the military are holding steady.
Until and unless this changes, Ahmedinejad looks quite secure — green paint and massive street protests notwithstanding.
[update, one day later: Supreme Leader Khameini has come out strongly in support of Ahmadinejad. Since Khameini was the only one who could constitutionally undo the elections, this means there’s very little chance now of a peaceful win for the protesters.]