thirty-seven million as of 2004, outnumber the six million Jews killed in Europe). Whether or not one feels so strongly about abortion, it re- mains a singularly charged issue. Anthony V. Bouza, a former top po- lice official in both the Bronx and Minneapolis, discovered this when he ran for Minnesota governor in 1994. A few years earlier, Bouza had written a book in which he called abortion "arguably the only effec- tive crime-prevention device adopted in this nation since the late 1960s." When Bouzas opinion was publicized just before the elec- tion, he fell sharply in the polls. And then he lost. However a person feels about abortion, a question is likely to come to mind: what are we to make of the trade-off of more abortion for less crime? Is it even possible to put a number on such a complicated transaction? As it happens, economists have a curious habit of affixing numbers to complicated transactions. Consider the effort to save the northern spotted owl from extinction. One economic study found that in order to protect roughly five thousand owls, the opportunity costs-that is, the income surrendered by the logging industry and others-would be $46 billion, or just over $9 million per owl. After the Exxon Valdez oil spill in 1989, another study estimated the amount that the typical American household would be willing to pay to avoid another such disaster: $31. An economist can affix a value even to a particular body part. Consider the schedule that the state of Connecticut uses to com- pensate for work-related injuries.     LOST OR DAMAGED BODY PART COMPENSATED WEEKS OF PAY   Finger (first) 36   Finger (second) 29 W her e Ha v e All the Criminals Gone ?     LOST OR DAMAGED BODY PART COMPENSATED WEEKS OF PAY   Finger (third) 21