Crime is more than an intellectual puzzle, it is a major social problem. Scholars and scientists in many different intellectual traditions have struggled to explain crime over the centuries. Christian theologians, for example, explained evil in terms of Original Sin. Evolutionary biologists saw criminals as trying to obtain reproductive advantage. Psychologists locate the cause for crime in the individual criminal, while sociologists argue that social conditions of inequality and lack of social cohesion cause crime. What makes the work of Herrnstein and Wilson original is that their explanation is interdisciplinary, attempting to fuse psychology and political theory.
The majority of the book is a review of earlier theories of crime, including both their strengths and weaknesses. While Herrnstein and Wilson admit that certain environmental factors do influence crime, and that there is a certain degree of biological determinism (women across all societies and eras are less likely to be criminals than men, for example) they also argue for individual choice and responsibility. In particular, they make the point that in the calculus of immediate benefit versus future possible punishment, criminals are more likely than average to overvalue immediate gratification and undervalue future negative effects. Thus rather than pure biological determinism, the book advocates a more nuanced theory that combines biological predisposition with individual choice and responsibility.