4. Unthinkability bias.

Finally, beyond the enhanced fundraising and core of strong supporters, candidates like Trump and Sanders have benefitted from what I dubbed “unthinkability bias” in 2016. This is like a strong version of confirmation bias, where people set their prior probabilities of an event occurring to zero and refuse to update their priors because they just can’t conceive of the possibility coming to pass. In the summer of 2016, I wrote a series of pieces suggesting that Trump could win the general election; these were met such derision and invective that I took a month-long break from Twitter. In late 2019, I wrote a piece suggesting that people were underestimating Sanders’ chances of becoming the Democratic nominee. While the response was less angry, it was still met with a degree of skepticism that seems unwarranted today.

This is harmless in and of itself, but it has the potential to transform the trajectory of races. By writing off Trump and Sanders in the summer and fall before the election year, candidates allowed their candidacies to strengthen and their core bases of support to grow. In addition, by attacking each other, the more “traditional” candidates collectively weakened themselves, diminishing themselves compared to the insurgent.