Problem is, there always will be murderers, abusers and thieves. Preventing crime is the right thing to do, but I don't think it is the answer for determining right degree of punishment if a crime is committed.
Okay, consider this: you're talking about punishment.
What, exactly, is the point of punishment?
Are you trying to prevent future crimes? Great, we're actually talking about crime prevention and severity of punishment is a red herring (because we actually need to consider punishment as merely one option among many).
Are you trying to satisfy victims? Okay, but now you're saying the punishment basically serves as a synthesised substitute for mob justice -- so why pretend there's anything humane about it at all?
Are you trying to deter other would-be criminals from doing the same? Great, we can actually measure the effectiveness of that empirically (spoiler: it's not great) and adjust punishments accordingly.
Or we can just build more prisons and put more people in jail (or murder them if we really don't like them) because that has worked out so well in the US.
What, exactly, is the point of punishment?
Are you trying to prevent future crimes? Great, we're actually talking about crime prevention and severity of punishment is a red herring (because we actually need to consider punishment as merely one option among many).
Are you trying to satisfy victims? Okay, but now you're saying the punishment basically serves as a synthesised substitute for mob justice -- so why pretend there's anything humane about it at all?
Are you trying to deter other would-be criminals from doing the same? Great, we can actually measure the effectiveness of that empirically (spoiler: it's not great) and adjust punishments accordingly.
Or we can just build more prisons and put more people in jail (or murder them if we really don't like them) because that has worked out so well in the US.