The idea that historical events, catastrophes in particular, didn't happen on their own but were driven by the hidden machinations of malign influences has deep roots. The appeal is clear: we can ascribe these events not to human shortsightedness or frailty, or to the contingencies of fate and circumstance, but to unseen forces. Conspiracy theories and paranoia go hand in hand. Something, or someone, is trying to control our lives and to regain that...