Journal of International Affairs, Winter, 1969, pp. 1-35.
Violence, being instrumental by nature, is rational to the extent that it is effective in reaching the end which must justify it. And since when we act we never know with any amount of certainty the eventual consequences of what we are doing, violence can remain rational only if it pursues short-term goals. Violence does not promote causes, it promotes neither History nor Revolution, but it can indeed serve to dramatize grievances and to bring them to public attention. As Conor Cruise O’Brien once remarked, “Violence is sometimes needed for the voice of moderation to be heard.” And indeed, violence, contrary to what its prophets try to tell us, is a much more effective weapon of reformers than of revolutionists. (The often vehement denunciations of violence by Marxists did not spring from humane motives but from their awareness that revolutions are not the result of conspiracies and violent action.) France would not have received the most radical reform bill since Napoleon to change her antiquated education system without the riots of the French students [in May 1968], and no one would have dreamed of yielding to reforms of Columbia University without the riots during the  spring term.
The New York Review of Books