While Pinker makes a great show of relying on evidence—the 700-odd pages of this bulky treatise are stuffed with impressive-looking graphs and statistics—his argument that violence is on the way out does not, in the end, rest on scientific investigation. He cites numerous reasons for the change, including increasing wealth and the spread of democracy. For him, none is as important as the adoption of a particular view of the world: “The reason so many violent institutions succumbed within so short a span of time was that the arguments that slew them belong to a coherent philosophy that emerged during the Age of Reason and the Enlightenment. The ideas of thinkers like Hobbes, Spinoza, Descartes, Locke, David Hume, Mary Astell, Kant, Beccaria, Smith, Mary Wollstonecraft, Madison, Jefferson, Hamilton and John Stuart Mill coalesced into a worldview that we can call Enlightenment humanism.” (The italics are Pinker’s.)

Yet these are highly disparate thinkers, and it is far from clear that any coherent philosophy could have “coalesced” from their often incompatible ideas. The difficulty would be magnified if Pinker included Marx, Bakunin and Lenin, who undeniably belong within the extended family of intellectual movements that comprised the Enlightenment, but are left off the list. Like other latter-day partisans of “Enlightenment values,” Pinker prefers to ignore the fact that many Enlightenment thinkers have been doctrinally anti-liberal, while quite a few have favoured the large-scale use of political violence, from the Jacobins who insisted on the necessity of terror during the French revolution, to Engels who welcomed a world war in which the Slavs—“aborigines in the heart of Europe”—would be wiped out.