I feel like some acts are so morbid or perhaps even evil that they have implications completely independent of whatever horrible thing the victim may have done.
That's how I feel about capital punishment. It's not so much that we need to be above the act of murder when dealing with murderers, to be comparatively more noble for some ultimate third party, because I don't believe in any kind of cosmic final judgement. There's no outside perspective on us so how we "look" or just the intellectual concept of "sinking to their level" doesn't really matter to me so much. It's not even just about the falsely convicted, who serve as enough justification alone to do away with capital punishment.
I guess the most basic reason I'm against it is that I can feel sympathy for anyone regardless of what they deserve, as long as I can imagine being in their shoes. And when I imagine being strapped down and coldly, pitilessly executed by my own species, imagining the surreal terror of counting down to that moment and then seeing that part of society so divorced in nature from any other part you'd ever encounter in life, it just disturbs and terrifies me greatly. It's like the perfect nightmare to me. I can't point to any horrible crime on the part of a recipient that relieves me of that disturbance about the process.
I get as angry as anyone else at some of the crimes people commit, probably angrier than most. But still, the revulsion I feel at the act of ending a life is too great to be overcome even by that.
Plus, I feel emotionally and logically that there is no point to a punishment if the victim isn't going to be around to "savor" it and lament their choices and feel the weight of justice upon them. It's just, *bam* they cease to exist, they never had any concept or perspective on the fact that they are now dead for what they've done. They can't reflect on it. Where's the satisfaction in that kind of revenge? What's the purpose?