By the time you read this, Troy Davis will probably have been executed for a crime he probably didn't commit. (Update: At 11:08pm, Wednesday, Dahlia Lithwick of Slate reported that the state of Georgia had executed Troy Davis.)
Amanda Marcotte of Pandagon argues that, from here on out, death penalty abolitionists should focus on procedural arguments against the death penalty, as opposed to simply asserting that the death penalty is wrong. To change minds on capital punishment, we should stress that the justice system is fallible, racist, and classist and that it's foolish to give such a system the power of life and death.
Amanda's probably right about how to sway undecided voters on this issue. But I don't think that procedural objections to the death penalty are actually the strongest arguments.
I think the risk of killing an innocent person is a good enough reason to scrap the whole concept of judicial executions, but that probably only seems persuasive to me because I have a strong aversion to the state executing anyone. If I thought that the death penalty was synonymous with justice, I'd wave those concerns away.
The vast majority of people who are executed did all the murdering, raping, and mutilating they were found guilty of. The justice system makes mistakes in sending people to jail, too. That's unfortunate, but it's a cost of doing business. The answer is to make the system fairer, not to embrace across-the-board prison abolitionism. You can't give someone back the years that were wrongly taken from them any more than you can bring the back to life from a wrongful execution. We can commute death sentences, of course. But surely, more innocent people have died in prison than have been wrongly executed.
When I ask myself why I'm really against the death penalty–not just what I think other people will find persuasive–my bottom line is this: The state should only kill when it's absolutely necessary.