My apologies, I did not realise that a summary was missing. -- Olaf
• Punishment refers to a penalty imposed for wrongdoing.
• Legal punishment is penalties imposed by the state upon persons found guilty of a criminal offence.
The focus of our discussion is not what should or should not be considered a criminal offence but what role punishment should play in society.
These are four common justifications for state punishment (from wikipedia).
Criminal activities typically give a benefit to the offender and a loss to the victim. Punishment has been justified as a measure of retributive justice, in which the goal is to try to rebalance any unjust advantage gained by ensuring that the offender also suffers a loss. Sometimes viewed as a way of "getting even" with a wrongdoer — the suffering of the wrongdoer is seen as a desired goal in itself, even if it has no restorative benefits for the victim. One reason societies have administered punishments is to diminish the perceived need for retaliatory "street justice", blood feud and vigilantism.
Incapacitation as a justification of punishment refers to the offender’s ability to commit further offences being removed. Imprisonment separates offenders from the community, removing or reducing their ability to carry out certain crimes. The death penalty does this in a permanent (and irrevocable) way. In some societies, people who stole have been punished by having their hands amputated.
One reason given to justify punishment is that it is a measure to prevent people from committing an offence - deterring previous offenders from reoffending, and preventing those who may be contemplating an offence they have not committed from actually committing it. This punishment is intended to be sufficient that people would choose not to commit the crime rather than experience the punishment. The aim is to deter everyone in the community from committing offences.
Some punishment includes work to reform and rehabilitate the wrongdoer so that they will not commit the offence again. This is distinguished from deterrence, in that the goal here is to change the offender's attitude to what they have done, and make them come to see that their behavior was wrong.
Links and Articles
Stanford Encyclopedia of Philosophy article on Punishment