It takes a streak of foolhardiness to answer the question “What are you optimistic about?” Because any response would seem to taunt the fates to prove one wrong. But in 2007 I took the bait and ventured that every form of violence, when measured objectively, was in decline – a claim I buttressed with 100 graphs in my 2011 book The Better Angels of Our Nature. Friends advised me I was setting myself up for embarrassment: a war with Iran, a contest over oil, or a nuclear terrorist attack could erupt any day. And wasn’t I even a bit superstitious about the impending centennial of the first world war?
Though I was documenting the past rather than prognosticating, a decade’s worth of new data provides a chance to calibrate our understanding of global trends. In the early 21st century did a bunch of undulating curves fortuitously scrape bottom? Or, as I argued, was something systematic going on?
To any headline-clicker, the answer is obvious. The year 2015 began with the Charlie Hebdo massacre and proceeded to a failed ceasefire in Ukraine, atrocities by Islamic State, and a human catastrophe in Syria that has spilled over Europe’s borders.
Every year the eminent psychology professor updates the 100 graphs that appeared in his 2011 book The Better Angels of Our Nature, showing that every form of violence is in decline. Here are his latest findings.