> if someone can pull up a study showing that prison sentences don't have any deterrent effect over other forms of punishment then I'd accept I'm wrong...
This is not some joe-schmoe study either, from the executive summary:
"Fifty studies dating from 1958 involving 336,052 offenders produced 325 correlations between recidivism and (a) length of time in prison and recidivism or (b) serving a prison sentence vs. receiving a community-based sanction."
In particular:
"The essential conclusions reached from this study were:
1. Prisons should not be used with the expectation of reducing criminal behaviour.
2. On the basis of the present results, excessive use of incarceration has enormous cost implications.
3. In order to determine who is being adversely affected by prison, it is incumbent upon prison officials to implement repeated, comprehensive assessments of offenders’ attitudes, values, and behaviours while incarcerated.
4. The primary justification of prison should be to incapacitate offenders (particularly, those of a chronic, higher risk nature) for reasonable periods and to exact retribution."
Summary points 1 and 4 are key: Prisons are not effective deterrence, but they are great tools for indirect retribution suffered by the victim(s).
Also in response to your last comment "I'd be somewhat shocked [..]": There are plenty of things that goes against simple human intuition--that's what science is for. Believe the facts, and disregard intuition.
That study only looks at the deterrent effect on existing criminals, not the general populace. I think there is confusion about the word "deterrent". I always thought about 'deterrent' in this context as: "Prisons are a deterrent.. just the thought of serving time in jail will deter anyone from committing a crime." Whereas the study you linked reports: "We have found that criminals who serve longer sentence are no more deterred from committing another crime than those who served short sentences."
Fair enough. There are plenty of studies out there regarding this topic, though a definitive conclusion is probably beyond any one single study. See papers Justin McCrary have published (he's done quite a bit of work in this area).
One such paper takes an interesting approach, combing the criminal records to see if the fact that deterrence is stiffened after 18 has an deterrent effect on crime rate by comparing juvenile offenders that are months pre-18 and 'adult' offenders that have just recently turned 18. The finding is 'surprisingly' a negative. Only very minor drop off rate is seen.
Certainly: http://www.prisonpolicy.org/scans/e199912.htm
This is not some joe-schmoe study either, from the executive summary: "Fifty studies dating from 1958 involving 336,052 offenders produced 325 correlations between recidivism and (a) length of time in prison and recidivism or (b) serving a prison sentence vs. receiving a community-based sanction."
In particular: "The essential conclusions reached from this study were:
1. Prisons should not be used with the expectation of reducing criminal behaviour.
2. On the basis of the present results, excessive use of incarceration has enormous cost implications.
3. In order to determine who is being adversely affected by prison, it is incumbent upon prison officials to implement repeated, comprehensive assessments of offenders’ attitudes, values, and behaviours while incarcerated.
4. The primary justification of prison should be to incapacitate offenders (particularly, those of a chronic, higher risk nature) for reasonable periods and to exact retribution."
Summary points 1 and 4 are key: Prisons are not effective deterrence, but they are great tools for indirect retribution suffered by the victim(s).
Also in response to your last comment "I'd be somewhat shocked [..]": There are plenty of things that goes against simple human intuition--that's what science is for. Believe the facts, and disregard intuition.