  Consider the following example of a social-scientific debate: During the 1990s, there was a precipitous decline in violent crime in the United States. Many social scientists naturally began to apply themselves to the question of why this had occurred, i.e., they set out to explain the phenomenon. A number of different hypotheses were advanced: the hiring of more police, changes in community policing practices, more severe sentencing guidelines for offenders, decreased tolerance for minor infractions, an increase in religiosity, a decline in the popularity of crack, changes in the demographic profile of the population, etc. Since the decline in crime occurred in many different jurisdictions, each using some different combination of strategies under different circumstances, it is possible to build support for different hypotheses through purely statistical analysis. For example, the idea that policing strategies play an important role is contradicted by the fact that New York City and San Francisco adopted very different approaches to policing, and yet experienced a similar decline in the crime rate. Thus a very sophisticated debate broke out, with different social scientists producing different data sets, and crunching the numbers in different ways, in support of their rival hypotheses.