Anyone who has lived through moments when a dictatorship was about to fall and democracy become a real possibility remembers almost constant tension, hopes that repeatedly alternated with fears, outbursts of enthusiasm and the pain of defeat. Every step seems difficult and yet nothing seems out of reach. But as one looks for the turning-points, a particular moment appears as a threshold, as a break. At one moment dictatorship has disappeared and has been replaced by democracy.

Since this is a “moment” in a world of stylized facts, let me first provide some context, a sort of logical chronology of the processes of transition from dictatorship to democracy. Without entering into a general discussion of authoritarian regimes, which has recently received extensive attention in the work of Juan Linz and Guillermo O'Donnell, I wish to emphasize one characteristic of authoritarian systems (which I will also call “dictatorships,” abandoning some important distinctions). The essential feature of such regimes is that someone has an effective capacity to prevent political outcomes that would be highly adverse to their interests. That “someone” can be an individual, the leader, or an organization, such as the armed forces, the police, the party, or the bureaucracy, or even a less easily identifiable “ring” of groups and individuals. I will speak below of the “authoritarian power apparatus” and introduce distinctions only when they are enlightening for the problem at hand.