Don’t expect a new wave of democratization.

How to explain the Tunisian revolution? By consulting Samuel Huntington—not the Huntington of Clash of Civilizations fame, but the author of The Third Wave: Democratization in the Late Twentieth Century, published in 1991. His model is too complex to be laid out here in all of its subtleties. But the basic message, to borrow from Bill Clinton’s 1992 campaign, is: “It’s the economy, stupid!” We should also add education, urbanization, and globalization—all those items that go into the tale “The Making of a Middle Class.” Tunisia has it all, and that is why it now sticks out like a bloody thumb from the rest of the Arab world, that vast arc from Rabat to Damascus where politics remains frozen, where the birth rate keeps dwarfing economic growth, and where King or Colonel is despotism’s name.

The Tunisian revolt fits Huntington’s model to a T. Looking at the third wave of democratization between 1974 and 1989, he found that rising wealth spells falling tyrants. How much money did it take? A per-capita income between $1,000 and $3,000, which would now be adjusted for inflation. Of the non-democracies which moved into that range in the 1970s and 1980s, three-quarters got rid of their overlords. To illustrate the point, Huntington recalls how the Spanish finance minister predicted in 1960 that his country would tumble into the democratic column once it had reached $2,000. Huntington’s terse comment: “It did”—in 1975.

That was then, but what about Tunisia now? The country has a per-capita income of $4,300, which would have been $1,000 in 1975. To make the analogy even more uncanny, let’s jiggle the numbers a bit and use purchasing-power parity. In that case Tunisia clocks in at $9,000—that is, at $2,200 in 1975 dollars. Just like Spain when it went democratic a generation ago.

So will Tunisia become the first democracy in the Arab arc of authoritarianism? Don’t hold your breath, but consult Huntington again. No economic determinist, he inserted a cautionary note on politics and biology into the story of Spain’s redemption. Francisco Franco, Spain’s dictator for 40 years, also died in 1975. And there was more serendipity: Had King Juan Carlos not been committed to democracy, “polarization could have led to social violence.”

True, Tunisian President Ben Ali has bolted from the country, but there is no Juan Carlos in the game—a figure of authority and legitimacy. Hence, violence erupted, as it did not in Spain. Hence, there is a bloody stand-off, with the old regime holding on to power by inviting a few opposition leaders into the government. Also recall that no regime in the wider neighborhood has been toppled from below—neither Algeria’s nor Iran’s.