One more thing about the Steven Pinker interview in the Guardian, previously kvetched about here in October. The interview leads with a very strange table, which lists mass killings (mostly wars, with a sprinkling of famines and non-state-certified genocides) and ranks them by “Death Toll (2oC equivalent.) “The table takes past conflicts and tyrannies,” the Guardian explains, “and recalibrates their death tolls so their scale can be compared directly.” In other words, you take the total death toll and you divide by the world population at the time; a single murder two thousand years ago is the equivalent, in this sense, of a 20-person killing spree now.
Bad idea! I wrote in Slate a while ago about the folly of computations of this kind — in particular, why killing one Israeli is not the “equivalent” of killing 47 Americans.
(Not to mention the fact that the table asks us to compare “The Middle East Slave Trade,” which took 1200 years to rack up its total of 132 million “20th century deaths” (constituting 18m actual slaves), to World War II, which killed its 55m in half a decade.)
None of which is meant to argue against the thesis of Pinker’s book, which seems pretty uncontroversial. I haven’t read it, but there’s no doubt that Pinker has access to, and uses, more sophisticated quantitative methodology than dividing one number by another and calling it a day.