Harvard professor Henry Louis Gates, Jr.’s arrest outside his home on July 16 has triggered a familiar media frenzy on the topic of race and policing. Nothing that has emerged to date suggests that Cambridge Police Sergeant James Crowley was motivated by racial bias in arresting Gates for disorderly conduct.

The broader discussion about whether the police in general are biased has been in turn characterized by two standard lacunae: Silence about minority crime rates and about the massive benefits to urban neighborhoods from proactive policing.