Human life is one mistake after another. We make mistakes, detect them, repair them, then go on to make more mistakes. Errors and error correction fill our days. If we are lucky, smart, or surrounded by helpful critics, error correction outweighs error, so that competence and knowledge actually improve – at least for a while. Certainly my own experience as a student and teacher of political processes has told me so. Repeatedly I have thought I had identified an important principle, proved a crucial point, or found a superior way of communicating an argument only to discover that the principle suffered exceptions, the proof failed to convince, or the new rhetoric caused misunderstandings I had not anticipated.

My first book refuted my doctoral dissertation, a fact at least guaranteeing that the author under attack would not complain. This book's vision of violence corrects mistakes I made during the 1970s. At that time I denied that collective violence constituted a causally coherent domain, but argued that “most” collective violence occurred as a by-product of negotiations that were not in themselves intrinsically violent. Another thirty years of work on political conflict helped me see the error of my earlier ways.

Although I still deny the existence of general laws from which we can deduce all particular cases of collective violence, I now believe that a fairly small number of causal mechanisms and processes recur throughout the whole range of collective violence – with different initial conditions, combinations, and sequences producing systematic variation from time to time and setting to setting in the character, intensity, and incidence of violent encounters.