Understanding randomness is a double-edged sword: Leonard Mlodinow's "The Drunkard's Walk: How Randomness Rules our Lives" is a great book on an important subject. As data scientists know, random phenomenon are everywhere, and humans don't understand them well. We're not wired to understand them well. This book is a huge help, and will be a relief to anyone who's heard people say "I don't believe in global warming because last winter we got a lot of snow," or some load of crap like that.