Why do some people take pleasure in cruelty?

Delroy Paulhus, a professor of psychology at the University of British Columbia in Canada studies the dark side of human beings to define the different flavors of everyday evil.

Paulhus has created a series of tests to identify people who have a “dark personality.” He works to answer the question: Why do some people take pleasure in cruelty? Not just psychopaths and murderers — but school bullies, internet trolls and even apparently upstanding members of society such as politicians and policemen.

Paulhus tends to focus on everyday evil rather than criminal or psychiatric cases. Others have called narcissism, Machiavellianism and psychopathy the “Dark Triad,” which is a triple whammy of nastiness. Paulhus adds another category sadism — to form a “Dark Tetrad.”

Psychology: the man who studies everyday evil, from BBC Future.