@Thomas,
I will not make the unimaginative argument that we have failed to get rid of slavery-- and that (although we have changed the mores in modern Western societies) we certainly have done nothing to change that part of human nature that leads to slavery.
Rather, let's have the imaginative discussion about what a world without violence or warfare would be like.
- Would it be at the cost of diversity (the idea of getting rid of religious differences has been raised-- an idea that I find distasteful if not scary)? I don't want to live in a world where I can't choose to be part of whatever religion I meaningful.
- What would we do with individuals who didn't want to evolve, adapt or learn to not engage in violence or warfare? I assume violence is out of the question.
- Are we talking about a social program that all individuals will be forced to participate in? Or are we really talking about eugenics here (where humans will change genetically).
If we are not talking about an unchangeable part of human nature, how would we go about changing it?