of confusion and contradiction. So the aim of this book is to explore the hidden side of . . . every- thing. This may occasionally be a frustrating exercise. It may some- times feel as if we are peering at the world through a straw or even staring into a funhouse mirror; but the idea is to look at many differ- ent scenarios and examine them in a way they have rarely been exam- ined. In some regards, this is a strange concept for a book. Most books put forth a single theme, crisply expressed in a sentence or two, and then tell the entire story of that theme: the history of salt; the fragility of democracy; the use and misuse of punctuation. This book boasts no such unifying theme. We did consider, for about six minutes, writ- ing a book that would revolve around a single theme-the theory and practice of applied microeconomics, anyone?-but opted instead for a sort of treasure-hunt approach. Yes, this approach employs the best analytical tools that economics can offer, but it also allows us to follow whatever freakish curiosities may occur to us. Thus our invented field of study: Freakonomics. The sort of stories told in this book are not often covered in Econ. 101, but that may change. Since the science of economics is primarily a set of tools, as opposed to a subject matter, then no subject, however offbeat, need be beyond its reach. It is worth remembering that Adam Smith, the founder of classical economics, was first and foremost a philosopher. He strove to be a moralist and, in doing so, became an economist. When he published       Intr oduction: T he Hidden Side o f E v erything     The Theory of Moral Sentiments in 1759, modern capitalism was just getting under way. Smith was entranced by the sweeping changes wrought by this new force, but it wasnt only the numbers that inter- ested him. It was the human effect, the fact that economic forces were vastly changing the way a person thought and behaved in a given sit-