Is your belief based in something? You say "shouldn't be able to..." but, like, why not? To convince anyone else of it you'd have to agree on the framework in which states are and aren't allowed to do things.
I think for most people the intuition is something like: the state is there to protect people (in principle at least); when someone is sufficiently dangerous to others they forfeit this right and it becomes just about protecting others from them; whereupon 'vengeance' is basically permitted against them, but then this is also delegated to the state to deter people from doing it individually because that's destabilizing, hence a death penalty.
Seems pretty natural to me unless you happen to have an infinite negative weight assigned to killing someone, which I do not. I mean, I have a large negative one, but it's not infinite. (Maybe yours is, perhaps from the catholic upbringing, which is why this doesn't make sense?)
(No idea what the neighbor thing has to do it; obviously nobody is arguing that neighbors should be (legally) able to kill anyone.)
> I think for most people the intuition is something like: the state is there to protect people (in principle at least); when someone is sufficiently dangerous to others they forfeit this right and it becomes just about protecting others from them; whereupon 'vengeance' is basically permitted against them
There's no connection between "protect[ing] people" and "vengeance", The latter is not necessary for the former.
The retributive instinct should not be "fed" by the State. It is perfectly normal to have that feeling, but we should recognize it for what it is and let it stay as such. You might think this isn't possible or stable but the Nordics would prove you wrong.
> Seems pretty natural to me unless you happen to have an infinite negative weight assigned to killing someone, which I do not. I mean, I have a large negative one, but it's not infinite.
What's your negative weight on killing someone who is innocent? A justice system cannot be perfect. There are too many people, too many motivations/biases, and too much nuance involved. If a justice system is not perfect and it executes people, innocent people will have their lives unjustly taken from them by us. If it's 99.9% accurate (I'd argue that even 99% is an impossibly high bar), then an innocent person has likely been intentionally killed by the federal and/or state governments in the last 20 years. Are you cool with that? After execution, it's not generally possible to file an appeal on behalf of the executed even if new evidence demonstrates innocence. This has the implication of multiple injustices - an innocent person is killed by the state, the true murderer gets no punishment, and society incurs the risk of wrongful execution with no protection from the true murderer.
Or we could take the less expensive, partially reversible route of putting the convicted in jail until they die.
If you'd like to understand the imperfection more concretely: https://en.wikipedia.org/wiki/List_of_wrongful_convictions_i...