Earlier this week, a woman wrote in to Slate's Dear Prudence advice chat asking whether it's considered lying to allow her daughter, who is three, to continue to believe in Santa Claus. Prudie's take: Nah. "Reality will eventually out," wrote the columnist, Emily Yoffe, "but theres so much reality in this life, that one of the delights of childhood, and of being a parent, is to spread a little fairy dust occasionally." Later in the chat, though, another person wrote in saying that his or her parents kept the Santa thing going until the writer was nine, at which point...