Crowds of people take to the street to protest a dictatorship. Despite gathering peacefully, they are set upon by the police and gangs of thugs, who beat them mercilessly. A student, never having attended a demonstration before, is shot and left for dead by the cops. Official media falsely blames the demonstrators for the violence, while agent provocateurs try to create pretexts to crack down on demonstrators even harder.
If the situation I describe was present-day Tehran, would anybody be surprised if people decided to fight back against such repression? And, would anyone blame them? Push people hard enough and they snap.
Yet the above scenario is not Tehran, 2009, but Berlin, 1967. A protest against the then Shah of Iran — a Western-backed tyrant with oil — was brutally attacked by the police and pro-Shah demonstrators (including the Shah's secret police), and student Benno Ohnesorg was killed in cold blood. This was a turning point for many who were there; bloodied and filled with loathing, the students regrouped and discussed what should be done.