We all like to think that the line between good and evil is impermeable--that people who do terrible things, such as commit murder, treason, or kidnapping, are on the evil side of this line, and the rest of us could never cross it. But the Stanford Prison Experiment and the Milgram studies revealed the permeability of that line. Some people are on the good side only because situations have never coerced or seduced them to cross over.