"Jesus? He would have been just one of many Jewish sect leaders of his day, had he not had St. Paul to proselytize and the Roman Empire to finish the job."

"Genghis Khan? The mere beneficiary of heavy rainfall. Adolf Hitler? 'Hitler’s own life before the age of 30 gave no hint of his subsequent qualities as Germany’s leader,' Diamond writes. 'How, then, can we claim that no one else could have become the mature Hitler?' How indeed? Figuring out how to separate historical forces from human agency has puzzled scholars since the days of Herodotus and Thucydides.... Now, [Jared] Diamond proposes a new tool for assessing leaders. Rather than using 'the biographic method' of studying leaders in their own context, he suggests the 'natural experiment.' Social scientists have used natural experiments — finding occasions where life allows them to run comparative data studies — to analyze things like the economic impact of the minimum wage. Diamond claims that natural experiments also have significant potential in political history, religious studies and sports. The problem is, they don’t really work.... Can the natural experiment help us figure out the historical effect of a president being assassinated — or narrowly escaping such a fate?"

I'm reading "What Is It About Jesus Christ and Genghis Khan? In “Profits, Prophets, Coaches, and Kings,” Jared Diamond considers the impact leaders might have had on the course of their civilizations" (NYT gift link).

That's Dan Jones — author of "The Plantagenets: The Kings Who Made England" — reviewing the new Jared Diamond book (commission earned).