I've disagreed with people before on this topic; I feel that the primary goals of the system should be rehabilitation (so that society can make productive use of former offenders) and deterrence. I've discussed it with people who seem to argue the primary goal is punishment - perhaps this is intended to work as deterrence, but it's clear that this is not the case. A "you were bad, now you get punished" mindset seems to be at work, rather than one seeking to solve the issues. The notion that people who committed crimes should not be allowed to learn new skills or seek ways of bettering themselves because they are being punished is not uncommon, even though this removes an opportunity for people to try and get out of a criminal lifestyle.
On the other hand, recidivism is pretty high in Ireland, and I've heard that here and elsewhere, prison is practically a criminal education centre. Sentences are often inconsistent - I'll try find some examples of weird sentencing - and often cut short.
The only conclusion I can draw here is that current system is a total mess, and needs significant overhaul.
I'm okay with capital punishment for particularly serious crimes. There was a good post on this recently.
Final point: I've heard it said (though cannot find figures on this) that in parts of the US, the time spent waiting on death row is so long, that your life expectancy is higher if you murder someone when you're in your early twenties than if you stay on the streets. Interesting that choosing execution could be seen as a rational choice.
I tend to agree with you about rehabilitation being the primary requirement. I've also found that many people desire retribution first and foremost.
It seemed strange that civil service wasn't mentioned in the article. In my country it is quite common as a minor punishment. Undesirable jobs such as cleaning of public areas are at once highly visible (people can see that they are unpleasant, and that punishment is being carried out) and rehabilitative (a work ethic must be developed to carry out the sentence). Even this, however, is hard to contemplate, as i...
link: http://www.philosophersbeard.org/2012/07/why-prison-doesnt-work-and-what-to-do.html
I came across this short well-reasoned essay via reddit, but most of the discussion there was by people who (ironically enough) appeared not to have read it. The comment section under the article itself was similar. Some seemed not to have read the first paragraph.
The author's arguments against the imprisonment system, and for alternative methods of punishment, are interesting. They touch upon ideas which are hard to consider rationally. The very idea of punishment is something most people appear to find unpleasant. Indeed so it must be if something is to be considered a punishment.
I found some relevant previous discussion on Less Wrong (Crime and Punishment, The Wrath of Kahneman), and Overcoming Bias (Prison is Cruel), but these seem to be about specifics, and not the system in general.
I am curious both what the scientific consensus is on punishment systems, and what Less Wrong thinks of them. With such an emotionally charged issue, it's hard to find rational discussion about it.