If crime is going down, you shouldn't be increasing resources for crime prevention. Or you should be taking note of what has worked and concentrate the crime-prevention methods on policies that have a track record of success.

Morality, then, is not a set of arbitrary regulations dictated by a vengeful deity and written down in a book; nor is it the custom of a particular culture or tribe. It is a consequence of the interchangeability of perspectives and the opportunity the world provides for positive-sum games.

Consistent style prevents presentation from getting in the way of content.

The task of evolutionary psychology is not to weigh in on human nature, a task better left to others. It is to add the satisfying kind of insight that only science can provide: to connect what we know about human nature with the rest of our knowledge of how the world works, and to explain the largest number of facts with the smallest number of assumptions.

We can make fun of hockey fans, but someone who enjoys Homer is indulging the same kind of vicarious bloodlust.

All over the world, belief in the supernatural has authorised the sacrifice of people to propitiate bloodthirsty gods, and the murder of witches for their malevolent powers.

The problem with the emotions is not that they are untamed forces or vestiges of our animal past; it is that they were designed to propagate copies of the genes that built them rather than to promote happiness, wisdom, or moral values.