"The notion that bad individuals should not be allowed to prosper does not exist in most species, yet it has been crucial to human evolution. It permits collaboration and has thus done as much as language and culture to allow human civilisation to flourish and people to dominate the planet.
A sense of justice argues that people should be free to keep the fruits of their labours, but also that the over-mighty rich need to be cut down from time to time and the poor occasionally exalted. It damns the murderer while recognising that, sometimes, even murder is justified. The perverted bargain with justice which Tosca makes is the heart of the opera’s tragedy. A sense of justice, then, reins in people’s other Darwinian instincts and curbs their excesses. For human nature has evolved to be both good and bad—and it is evolution that allows human nature to know the difference."
The Economist, December 18th, 2008