Read a Feb. 8, 2005, New York Times article posted by the web site s8int.com about how the scientific world approaches the concept of evil.

Listen to a National Public Radio segment on the nature of evil from April 8, 1999.

Read a June 13, 2011, New York Times review of British scholar Simon Baron-Cohen’s book, The Science of Evil: On Empathy and the Origins of Cruelty. See also an excerpt of the book.

Philip Zimbardo, Stanford University professor emeritus of psychology, is the author of The Lucifer Effect: Understanding How Good People Turn Evil. He was director of the Stanford Prison Experiment.

Hannah Decker is a University of Houston history professor and a scholar of German history. She teaches graduate seminars on Nazi Germany and has co-taught a course on the history of evil.

Jerome Rosenberg, University of Alabama psychology professor, teaches courses on the Holocaust that examine the dark side of human behavior and the nature of good and evil.

John Donelson Ross Forsyth holds the Colonel Leo K. and Gaylee Thorsness Chair in Ethical Leadership at the Jepson School of Leadership Studies of the University of Richmond and teaches a course in the psychology of good and evil.

Dr. Michael Welner, a forensic psychiatrist at New York University School of Medicine, is founder of the Forensic Panel, which is developing a standardized “depravity scale” to determine whether specific crimes reflect depraved intent, actions and/or attitudes.

Dr. Michael Stone, a professor of clinical psychiatry at Columbia College of Physicians and Surgeons, has been called “the Einstein of Evil.” Stone developed a “Gradations of Evil Scale” for ranking homicides and was host of the Discovery Channel’s series Most Evil from 2006 to 2008. His books include The Anatomy of Evil (2009).