A paper called “The Dynamics of Deterrence,”by Beau Kilmer of RAND and the undersigned, will be published in the Proceedings of the National Academy of Sciences sometime next week. This space seems like a good place to sum up the paper for those RBC readers (no doubt a small minority) who haven’t yet been elected to the National Academy.
At first blush, there would appear to be a tradeoff between crime and punishment: if punishment deters offending, then less punishment means more offending. The key insight of the paper is that there’s a way around that: it’s possible to have both less offending and less punishment by taking advantage of positive-feedback effects and by substituting convincing threats for the actual infliction of penalties. (Yes, this is the central argument of my new book.)
The apparent paradox that drives the result is that increasing the level of punishment available can actually reduce the level of punishment actually administered, if the threat of punishment succeeds in deterring violations. As Schelling says, the very definition of a successful deterrent threat is that it doesn’t have to be carried out.
Because the risk of punishment faced by an offender depends not only on the capacity of the authorities to punish but also on the rate of offending, there is a natural positive feedback in offending rates. More offending means less risk for each offender; that’s the logical structure of a riot. By the same token, as violation rates fall the risk of being punished for those who do offend rises. That creates the possibility of “tipping” effects, situations which have both high-violation and low-violation equilibria. In such a “tipping” situation, even a temporary increase in enforcement can lead to a lasting decrease in violation rates, and – this is the key point – that decrease can be sustained even after the additional enforcement resources are withdrawn.
That leads to a strategic proposal: when there’s not enough capacity to deter every possible violator of every rule – as there generally isn’t – then it makes sense to concentrate threats on some subset of offenses or offenders or areas, “tip” that subset to the low-offending equilibrium, and then move on. Because enforcement is costly and enforcement capacity is scarce, enforcers and potential violators actually share a common interest in having actual punishment not happen; therefore, authorities ought in general to “telegraph their punches,” issuing specific warnings to specific people in order to reduce the cost of the transition from high to low offending.
A variety of actual enforcement successes, from the crackdown on squeegee operators and subway vandals in New York and the Cease-Fire gang-homicide intervention in Boston to low-arrest drug market disruptions in High Point and East Hempstead to the HOPE program in Honolulu, illustrate the potential of the focused-deterrence approach to get us out of our current high-crime, high-punishment social trap.