The main assumption on which this book is built is that economics as a science has the right tools but asks the wrong questions. The authors, a »rogue« professor of economics and a journalist specialising in the economy, vow to put these instruments to good use on interesting questions.
For example, they ask why drug dealers so often live with their mothers. And come up with the hardly surprising answer that the pay of the average (lowly) drug dealer on the street is disastrously low. Or they ask why, against all expectations, crime rates in the US suddenly and enduringly dropped from the mid-90s. And come up with the much more interesting answer that the mid 90s were also the period in which children who were not born due to the legalisation of abortion in the 1970s would have reached criminal adulthood.
The latter example explains why I believe the whole branding of this book (or the authors, for that matter) is a misnomer. The book is built on statistics, on identifying correlations and isolating causes and effects. Granted, economists also make use of these methods - but that does certainly not make these methods the sole property of economics.
Levitt, a professor of economics no less, flirtatiously concedes that he does not know the first thing about economics. He may be right, I believe. There is one fundamental claim made in this book that truly falls in the realm of economics: That people always act on incentives and that in order to understand and predict human behaviour you only have to look out for the incentives involved. I do not agree. Young men embarking on a career as drug dealers although pay is pathetic and the risk of serious injury or death on the job very real – where are the incentives? Of course, if you apply a very broad definition of incentive, such as »what makes people want something«, then you can e.g. name hope for better payment as an incentive for apprentice drug dealers. But if you employ such a broad definition, the term cannot serve as an explanation, it merely labels the inexplicable (why do people, against all the obvious evidence to the contrary, hope for better pay in this carreer?)
I do not believe this book has much more to do with economics than just any book in a capitalist world. Still, the book makes for enjoyable reading and is good training in looking for concealed correlations and explanations.