... for the same reason we all rail against destructiveness in our lives: Because even killer if another comes to take the place of the first, the first can commit no more. We don't fight injustice in the hopes of eradicating all justice for ever and ever, we do so for the good that is done by the one effort. Why care about one when another will come is kind of like "Why wash your car when, sooner or later, it's just going to get dirty again?" - Because the dirt that was there is now gone, whether or not more comes to take its place isn't the point.

As far as minds, "... closed off to all vestiges of reason", now that's a whole other ballgame. Murdering the murder is ethically wrong (in my opinion), but a person (or a collection of people) has the right to protect themselves. "Removing" them (in one way or another) to eliminate further transgressions seems to be reasonable.

Of course, that gets very complicated...

Hope this helps, thanks for your post.

I haven't read the play, so may be off the mark here. The statement "... a souless killer who confronted people while pretending to be a killer..." seems confusing. Perhaps the role of the killer in the play was to represent the dark side of an "... otherwise utopiatic town..." If people are given complete freedom, then should that extend to illegal activities?

I would say that the killer can be killed to free the town of that particular killer. Certainly others will come after it, but those should also be eradicated, for the sake of the whole community.

Justice is essentially what you're talking about. I think justice is the protection of people from someone else, by any means. Granted, it is a never ending cycle, but without that justice, the larger group of people is as good as killed.