Twenty years have passed since the fall of the Berlin wall, one of the shameful symbols of the cold war and the dangerous division of the world into opposing blocks and spheres of influence. Today we can revisit the events of those times and take stock of them in a less emotional and more rational way.

The first optimistic observation to be made is that the announced "end of history" has not come about, though many claimed it had. But neither has the world that many politicians of my generation trusted and sincerely believed in: one in which, with the end of the cold war, humankind could finally forget the absurdity of the arms race, dangerous regional conflicts, and sterile ideological disputes, and enter a golden century of collective...