Good questions. The answer to your first question is, basically, all of the things you list in your second question, plus some. The justifications for criminal punishment are typically divided (oversimplistically) into two theories: "backward-looking" retribution and "forward-looking" consequentialism. The forward-looking theories (often associated with utilitarian ethics) focus on the future benefits of punishing criminals: (1) deterring the criminal from further crime, (2) deterring others from carrying out crimes, and perhaps also (3) rehabilitating the criminal and (4) restitution of the victims.

The backward-looking theories (often associated with Kantian ethics) focus on what happened in the past--the crime committed, the harm done, the guilt of the criminal--and aim to punish the criminal as much as he or she deserves it, which may include making the criminal suffer an appropriate amount, but perhaps also forcing him or her to make up for the crime with restitution. This justification may be seen as "exacting revenge," but revenge is typically more personal and not necessarily based on a moral justification.

Now, I suspect--and there's evidence to support--that we are motivated to punish criminals and others whom we perceive as doing us (or our loved ones) harm by strong feelings of resentment and indignation, and we feel relieved when we see these transgressors punished, including in significant cases, seeing them suffer or die (consider how people felt about bin Laden's death). These feelings likely evolved in part (and somewhat ironically) to promote social cohesion: Cheaters had to be punished severely to promote cooperation. But this suggests that our retributive impulses, and our feelings of revenge, may largely serve forward-looking goals--promoting social cohesion and preventing future wrong-doing.

But motivation is not the same as justification. The evolution of our legal system includes depersonalizing revenge, preventing the "spiral of revenge" (e.g., family feuds), and tamping down some of our impulses to punish severely and well beyond what people deserve (e.g., to send a message)--the 8th Amendment against cruel and unusual punishment illustrates this goal.

Notice that desert (retributive) theories may sometimes suggest less punishment than deterrent (consequentialist) theories--it may deter better to cut the hands off robbers. On the other hand, consequentialist theories often suggest less severe punishments, since the best future consequences are often served by trying to rehabilitate the criminal (e.g., educating him or her). If the death penalty does not deter (and the evidence suggests it doesn't), then consequentialist theories require getting rid of it. Retributive theories can still allow it, assuming some criminals deserve to be killed (theories of what people deserve open up lots of cans of worms, including whether people have the sort of free will that allows them to deserve punishment).

So, what sort of punishment would lead to the most just society? My own view is that it will include a hybrid justification, recognizing that giving people what they deserve (paying close attention to what capacities for rational control they have), with state-sanctioned (democratically approved) punishment, can play an important role in satisfying our sense of justice (including our deep feelings of retribution), while also serving the purpose of deterrence. But rehabilitation and restitution might best be served by helping those criminals who can be helped and allowing them to pay back their victims and society, rather than locking them up in nasty prisons.

These goals can compete. The "war on drugs" illustrates a conflict between harsh penalties justified by both desert and deterrence and treatments for addiction that would likely have better long-term consequences.

I hope these beginnings of answers to your complicated question are helpful!

There are a variety of ways of justifying punishment, not all utilitarian, and some would argue that punishing a criminal respects him or her since we apply a sanction to them which to some degree matches the crime. It is only sadistic if we enjoy their suffering, and surely most members of the public do not, especially as it is very expensive to incarcerate criminals. On your measure, causing any suffering at all is to bring about evil, and this is implausible. Sometimes offenders have to be brought face to face with the nature of their actions by punishing them, and they may reform or they may not, but they are not punished to make them suffer per se. The way in which this topic was described suggests that all punishment is evil, and we can easily think of cases where this is implausible.

I hear two things in what you say. One is that, quite understandably, you want to deal with your sorrow. The other is that you want a "serious, fair and moral" way past your situation. But I'm not sure these amount to the same thing.

When it comes to curing heartache, philosophers have no special expertise. A philosopher could offer you some obvious platitudes, including the suggestion that if you are really having trouble coping, there's no shame in seeking professional help, but a philosopher is not a doctor of the soul

On the other part of your plea, there may be a bit that a philosopher could say. You've accepted — intellectually, at least — that your former fiancé has lost her regard for you and that this is something you brought on your self. She is entitled to get on with her life, and the right thing to do is to respect that. But you're also looking for some way to atone and make amends.

Making amends may not be possible, because making amends isn't the sort of thing that can just happen one-sidedly. Your former fiancé may well not want to take part in the process and may feel that she owes you no such thing. A serious response calls for respecting that; a serious response calls for respecting her right not to be a party to your own attempt to get past what you've done. It would be fine to write to her (writing is less intrusive; and by writing I mean a real honest-to-goodness letter) and make clear that you will not intrude anymore. You can reiterate your regret; your can wish her well. But you can also assure her that you will leave her in peace, and you then must do just that.

Perhaps some day she will want to see you again; perhaps she won't. That is up to her and not up to you. Making it clear that you accept this and acting accordingly is a serious and decent way to bring your situation to a kind of formal close.

That's the philosophical part of the advice. I hope it doesn't seem unbearably austere. Following it may be difficult, though it may bring its own sort of release. That said, I do hope you'll take seriously the possibility that if, even after doing the right thing, your misery gets in the way of living your life, you should seek out the help of someone skilled at dealing with emotional pain.

I don't see what is special about rape from the evidence point of view. There are many crimes which take the form of one party saying one thing, and the other something else. In the Anglo-American legal system a jury may well have the opportunity to decide on who is telling the truth, and sometimes it is difficult and sometimes it is not. Juries have to decide what was going on in the minds of the accused and the other people involved in a vast variety of cases, including fraud, deception, conspiracy, murder and so on, and prejudice is potentially present in a whole variety of cases.

Given your question, you may be interested in a discussion of Strawson's NYTimes article at the free will/moral responsibility blog, Flickers of Freedom, here.

There's also a discussion on retribution and punishment (and psychopaths) at the blog here.

You'll see in these discussions that there are plenty of philosophers (called compatibilists) who think that free will and moral responsibility are possible even if determinism is true, and who reject Strawson's argument against the possibility of freedom and responsibility. These compatibilists will generally say that retributive punishment is justified, though they might also think that punishing (or treating) criminals for consequentialist reasons (such as deterrence and rehabilitation) is also important.

My own view is that we can have free will and moral responsibility (determinism is irrelevant to this issue), but that we have less than we think (because the sciences of the mind are showing that we have less self-knowledge and conscious control than we think). So, I think retributive punishment can be justified, but usually criminals deserve less of this sort of punishment than our system doles out. We should put more emphasis on the forward-looking purposes of punishment (or, if you wish, call it quarantine and rehabilitation).

You make two good points. On the first, re death penalty, I would agree that there are cases where it's crystal clear that the accused is guilty. But this is really beside the point. The question is whether we can design a mechanism that correctly identifies these cases. In the absence of such a mechanism, we must be especially reluctant to use the death penalty.

Your other point is that perhaps we should incorporate into criminal verdicts an assessment (by the judge or jury) of the degree of certainty. But again, there is the question how accurate this assessment would be. And there is the further point that it would look quite bad to impose a severe punishment on someone with the comment that we've just barely reached the minimally required level of certainty. Better then perhaps to handle this issue unofficially: just as jurors sometimes acquit someone who very clearly did what the law proscribes when they feel the person did nothing wrong (example: the killing of a suffering and terminally ill spouse), a judge may sometimes impose a lesser penalty because she is less than fully convinced that the person really committed the crime.

And a possibly interesting footnote on this second point. In the case of acquittals, as well, one could incorporate an assessment (by the judge or the jury) of the degree of certainty. And this is actually done, I believe, in Scottish jurisprudence, which allows -- aside from "guilty" and "innocent" -- a third verdict of "not proven." The accused goes free, but has not been fully cleared of the charges brought against her or him.