[mibbiting]

Nothing is 100% certain. If you perform a heart operation, there's a chance you'll kill the patient. Does that mean we should get rid of heart operations?

If you put a serial killer to death, you can be 100% sure they won't kill any more people. If you put him in prison, you can't. He may escape, or he may get released early and kill again. Or as often happens, he'll kill other prisoners whilst in prison.

It's a question of whether you value potential victims, or potential falsely convicted innocent people. IMHO the former is a far bigger problem.

[scarmig]

If there's a serial killer, even if you put a person accused of being that serial killer to death, you can't be sure that serial killer won't kill any more people. This isn't just an edge case: serial killers often claim credit for any and all crimes that might be attributed to them. Kill them off, attribute all the murders to them, and the actual serial killer is more likely to stay in the wild.

[gxs]

This is a bit of a red herring as I am making no assertions regarding what else may or may be assured 100%.

We have different tolerance for accuracy depending on the context, and my assertion was that in this case 100% would be necessary for, at least me, to feel comfortable carrying out the punishment.

[mibbiting]

But my point is that are you just "ignoring" the other side of the argument - if you don't put a serial killer to death, there's a chance others will be killed.

If you don't put them to death, can you be 100% sure saving that life isn't going to cause more people to die?

It's not simply a case of "punishment". It's preventing further crime and deaths.