Death penalty and utilitarianism

After I said in this post that I oppose the death penalty because of the problems of fallibility and process, DearieMe commented:

Would you still oppose capital punishment if (big "if" I'll grant you) someone demonstrated to your satisfaction that the number of 'murderers' executed in error was, say, an order of magnitude less than the number of lives saved by the deterrent effect? Or two orders of magnitude, or three....?

And then after a further comment by Dudley Sharp, he added:

Mr Sharp's comments imply that I could usefully modify my original question to include "the number of lives saved by the deterrent effect plus those saved by the prevention of further murders by convicted murderers". Does anyone gather British figures for homicides proven to be by convicted murderers? If not, why not?

The idea that the loss of innocent life might be justified if it prevents the loss of even more innocent life is, of course, a utilitarian argument. Mr Sharp also mentioned deterrence, but the part of his comment DM picked up on was important but different, and it hangs on the idea that convicted murderers might be released to re-offend. My post argued for whole life sentences in some cases, which would have the same preventative effect as a death penalty, though at greater expense. I think that expense is justified, because of the problems of fallibility and process. You can't release an executed person and there have been cases in this country at least of people being wrongly convicted for crimes that would surely have demanded the death penalty had it been in place - child murder (Stefan Kishko, Sally Clark) and terrorism (Guildford, Birmingham), for example.

So the experience here is that innocent people will be in danger of being killed if there is a death penalty. Whole life sentences remove the risk of further murders from those who have killed professionally of from some kind of mania and who are therefore a danger to society.

I think that brings us back to DM's original question, which is of a class that has been debated at other times: there is a group of people in a predicament, and the sacrifice of one or more will save the rest. For example, a ship sinks and ten people clamber onto a lifeboat that can only carry seven. The lifeboat starts to sink. Should three be thrown overboard, or should straws be drawn, or should volunteers be asked for, or should all perish?

I think the answer is that there is no right answer, because any premises on which any answers are based are, in fact, the real grounds of debate. It boils down to the importance placed on the individual and on the collective. In the case of the lifeboat, there's a real argument. If three people are thrown overboard it's just a matter of the merits of the selection process. If nobody is thrown overboard then these three people die anyway. Some might argue that this is the right choice, better that all die than that there is an injustice. This means weighing injustice against death. It's a different argument.

In the case of the death penalty, though, as DM states he postulates a very big if. I'm not aware there's any evidence that execution has any effect on murder rates in practice. Mr Sharp says there is, but provides no proper references. So this question is interesting in the abstract but should not be confused with an argument about capital punishment.

My own opinion is that we should strive for the least imperfect solution possible, without knowingly implementing any policies that would kill innocent people. It isn't especially compassionate, as a position. Many people facing the rest of their lives in prison are on suicide watch - we prevent them from carrying out their own death penalty for, as Kurt Vonnegut put it in Mother Night, crimes against themselves (I don't credit someone like Ian Brady with the humanity to sentence himself for the crimes he committed against others).

This is all about the fallibility issue, though. There's also the question of process. If a criminal abducted someone and imprisoned them for years, holding the threat of imminent death over them the whole time but letting them try to argue their way out of it, or throw dice, or examine the entrails of fish for signs that they should be killed or released - and legal process makes about as much sense and has as much rationality, for many of the convicted, as do these procedures; if they told them some mornings that they were to be killed later that day, or the next... then when the time came said "only kidding"; if they surrounded their victims with ritual, letting them choose their own food for that one fateful morning, making a ceremony of the murder, inviting spectators...

If a criminal did that, they'd be regarded as the most sadistic and horrible murderer of all time.