I disagree with the fact that a society without war could not define war/peace. That would be simular to not being able to imagine it. Humans have imagined *many* things that really do not exist.
One could argue, that these are somehow derived from things that do exist. Like war in space is simply combining space and war. Like darwinbots(.com) are an abstraction designed to attempt to emulate evolution. (cool, btw)
However, a single murder in such society would then lead to the concept of war. (although it would seem to insane for such a society perhaps.) Maybe even a single death, since someone could think that in principle, the cause of death could be created by a person. (indeed, this could perhaps even been seen as the cause of wars, and the way they are fought. Or it is an invention.)

@handy; I dont understand why your post did not meet more resistance. For one, the way it is said, seems to be viewing the universe as "utilitarian". Hell, i dont even what you mean with (in)finite in your post. And, what does it have to do with existence of absence anyway?