We recently attended a lecture on the history of propaganda. In fact, the point of the lecture was that history is propaganda—from Alexander the Great’s scribes through Julius Caesar and Napoleon, we can not assuredly separate fact from interpretation from self-generated myth.

But things have changed, you might think. We live in an era of reporting, and impartial fact-finding commissions, and data. All that is just so much persuasion, this speaker argued. Perhaps her most convincing riff was about Venn diagrams and how they appear to present clearly defined, even indisputable information, while actually being arbitrary circles drawn by self-interested PowerPoint users.