To hold criminals responsible for their crimes involves a failure to recognize that criminal actions, like all actions, are ultimately products of the environment that forged the agent' s character  It is not criminals but people in the law-abiding majority who by their actions do most to create and maintain this environment
Ttherefore, it is law-abiding people whose actions, and nothing else, make them alone truly responsible for crime
its conclusion contradicts an implicit principle on which an earlier part of the argument is based