The argument begins with criticisms of the motivational assumption that underlie opportunity theory. Opportunity theory, like many alternative theories about the causes of crime, rests on the assumption that people are always motivated by self- interest in their intentional actions. Theoretical grounds for rejecting an assumption that all voluntary acts are self- interested have been presented by a number of philosophers. Seven of their arguments are summarized. The author then suggests reasons why crime-prevention interventions based in this motivational assumption might be contributing to an increase in crime. The flawed theory that all motives are fundamentally self- interested leads to strategies that increase perceived risks of punishment to potential criminals. Such strategies are unlikely to be effective if potential criminals fail to perceive the punishment risks as unattractive. Yet there are grounds for believing that some would-be criminals perceive threats of punishments as challenges. The most persistent criminals are known to take risks that others avoid and to seek stimulation that others find noxious. Finally, this paper proposes a strategy for studying criminal behavior, a strategy that involves looking broadly at the behavior of those committing crimes, so as to understand their motives for voluntary actions. 91 references