Incentives matter, including the risks we are willing to run. This is only a commonsense observation about how people choose to behave. Yet controversy over the very existence of a deterrence and incapacitation effect of incarceration has raged in elite circles. The first duty of a scientist, it's been said, is to point out the obvious. The logic of deterrence is pretty obvious, but I must point to evidence too, which is overwhelming, for the negative impact of punishment on crime.
Evidence ranges from simple facts to sophisticated statistical and econometric studies.
Even experts who disagree with each other about some aspects of criminal justice are in agreement about deterrence. In sharp contrast to the situation ten years ago, experts who assert the contrary are fighting a rearguard action. Crime rates have fallen 30 percent over the last decade while the prison and jail population doubled to two million. As German philosopher Arthur Schopenhauer said, truth passes through three stages, first, it is ridiculed, second, it is violently opposed, and third, it is accepted as being self-evident. Given the avarice of man, the hard reality is that the threat of bad consequences, including public retribution posed by the legal system, is vital to secure human rights to life and property against predation.