Cruelty, violence, badness... This episode of Radiolab, we wrestle with the dark side of human nature, and ask whether it's something we can ever really understand, or fully escape. We encounter a man who scrambles our notions of good and evil, turn to one of the most famous (and misunderstood) psychology experiments ever, talk to a man who chased one of the most prolific serial killers in U.S. history, then got a chance to ask him the question that had haunted him for years: why?
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