Despite high-minded ideals, temptation always seems to loom around the corner, threatening to derail us into a desperate world of secret behavior and covered-up indiscretions. From families to marriages to businesses, on a scale as global as the credit default swap meltdown or as personal as our last session on the Internet, we are suckers for bad ideas. Why do we so often make poor decisions that can lead to life-shattering results? Why...