A major idea that emerged from the classical school was about the role of punishment in society. For Beccaria and for other classical school thinkers, the ultimate purpose of punishment was deterrence. Punishment should exist only to prevent future crimes from happening. In addition, if human behavior is based on rational and hedonistic principles, then it doesn’t make sense for society to punish drunk or insane people since they were not behaving rationally when they committed the crime. Similarly, from this point of view, it doesn’t make sense for a judge to punish someone only because the judge has a personal distaste for the offender.

To create the most effective system of deterrence, classical school thinkers introduced another important concept into criminology, that the punishment must be proportional (to be of equal degree) to the crime committed. Beccaria believed that if a serious crime had the same punishment as a less serious crime, then a potential criminal, if he had the motivation, would not be deterred from committing the more serious crime.

Another way to make sure that punishment would have the proper deterrence effect is to dispense punishment as soon as possible after the crime was committed. It is unjust to make the offender wait a long time in detention to receive his/her sentence. In addition, if there is a long delay between the punishment and the crime, the punishment will fail to produce a strong deterrence effect on society.