I don't think the argument that the world is getting more peaceful stands up to scrutiny. More peaceful as compared to when? Pre-industrial society? Sure, if you ignore the twentieth century, which... why would you do that? More peaceful since the end of the Cold War? Granted, but that's a really arbitrary date, especially considering that that wasn't that long ago. The West was pretty peaceful between 1871 and 1914, after all...
Pinker was arguing that the chance of someone dying a violent death has fallen precipitously over time (including deaths by homicide/fighting as well as larger-scale wars). This doesn't necessitate a decrease in war/conflict between groups, just that a smaller percentage of society would need to fight as you have a bigger, more specialized population.
