Steven Pinker has been getting much attention lately for arguing in his new book The Better Angels of Our Nature, against a lot of people's surface assumptions based on a pretty geopolitically violent past century, that modernity and the modern state have in fact made the world a far less violent place.
David Bentley Hart at First Things wonders if Pinker's measures make the most sense, given that we are still, after all, sitting on a pretty big pile of murdered bodies here in the aftermath of the 20th century:
Pinker's method for assessing the relative ferocity of different centuries is to calculate the total of violent deaths not as an absolute quantity, but as a percentage of global population. But statistical comparisons like that are notoriously vacuous. Population sample sizes can vary by billions, but a single life remains a static sum, so the smaller the sample the larger the percentage each life represents. Obviously, though, a remote Inuit village of one hundred souls where someone gets killed in a fistfight is not twice as violent as a nation of 200 million that exterminates one million of its citizens. And even where the orders of magnitude are not quite so divergent, comparison on a global scale is useless, especially since over the past century modern medicine has reduced infant mortality and radically extended life spans nearly everywhere (meaning, for one thing, there are now far more persons too young or too old to fight). So Pinker's assertion that a person would be thirty-five times more likely to be murdered in the Middle Ages than now is empirically meaningless.
In the end, what Pinker calls a "decline of violence" in modernity actually has been, in real body counts, a continual and extravagant increase in violence that has been outstripped by an even more exorbitant demographic explosion.
A Reason.tv inteview with Pinker: