Ever since June 15 in Tehran I’ve been asking the most alluring and treacherous of historical questions: “What if?”

What if the vast protesting crowd of perhaps three million people had turned from Azadi (Freedom) Square toward the presidential complex? What if Mir Hussein Moussavi, the opposition leader, had stood before the throng and said, “Here I stand with you and here I will fall?” What, in short, if Azadi had been Prague’s Wenceslas Square of 20 years ago and Moussavi had been Vaclav Havel?

In history, of course, the hypothetical has little value even if at any one moment — like that one in the Iranian capital three days after the disputed election — any number of outcomes was as plausible as what came to pass. Retrospective determinism (Henri Bergson’s phrase) now makes it hard to imagine anything other than the brutal clampdown that has pushed Iranian anger beneath the surface. Yet of course things might have ended differently.

In 1989, the revolutionary year, the Tiananmen Square massacre happened in Beijing and, five months later, the division of Europe ended with the fall of the Wall in Berlin. Could it have been otherwise? Might China have opened to greater democracy while European uprisings were shot down?

We cannot know any more than we know what lies on the road not taken or what a pregnant glance exchanged but never explored might have yielded. All we know, as Timothy Garton Ash observes in The New York Review of Books, is, “The fact that Tiananmen happened in China is one of the reasons it did not happen in Europe.”

... contd.