It's often assumed that criminologists know a great deal about violent offenders, but in fact, there is little consensus about what distinguishes them from those who commit less serious crimes. There is even less agreement about whether violent offenders can be distinguished from chronic, nonviolent offenders at all. The challenging question remains: why do some individuals commit violent offenses while so many others restrict themselves to nonviolent ones?

Thugs and Thieves argues that understanding the differential etiology of violence constitutes a fundamental chasm in the...