In his best-selling book The Black Swan, probabilist Nassim Nicholas Taleb warns against the need for easy narratives to explain the unexpected. Given how unexpected the result of this Tuesday’s election was, it is worth taking some time to review what Taleb calls “the narrative fallacy.”
According to Taleb,
The narrative fallacy addresses our limited ability to look at sequences of facts without weaving an explanation into them, or, equivalently, forcing a logical link, an arrow of relationship, upon them. Explanations bind facts together. They make them all the more easily remembered; they help them make more sense. Where this propensity can go wrong is when it increases our impression of understanding.
Yesterday, I reviewed New York Times exit polling data to try to look at what we actually know about who voted for president-elect Donald Trump or Sec. Hillary Clinton. The results, as I noted, were often surprising.
The reason they are surprising is precisely because of what Taleb gets at here: we have a tendency to want everything to fit into neat-and-tidy narratives. But reality rarely works that way, especially in the case of unexpected events. Donald Trump’s win was a Black Swan event to many.
By nearly every poll, Hillary Clinton was the favorite to win (and, of course, it appears she did win the popular vote). The most cautious index I saw was FiveThirtyEight, where to their credit they stressed the probabilistic nature of their forecast. They basically put the odds at 2-to-1 in favor of Clinton, and they even said that her chances were not as good as President Obama’s reelection in 2012. Even so, they too have been reeling at the inaccuracy of, again, basically every poll.
So Trump won. It wasn’t outside the realm of possibility (obviously now), but it was certainly unexpected to most, even some of those who gave him a better chance than others. How did it happen? (more…)