You want the boring reason or the fun one?
The boring reason, which also suffers from being circular, is because it’s a two-party system. Here’s the fun one:
Although a lot of voters would probably be happier with someone other than these two, they can’t agree on who it should be. So they fall back on Trump or Clinton, just to keep the one they like even less from winning. This is what game theorists call a “coordination problem.”
It’s a version of the famous Prisoner’s Dilemma game, in which suspects held in separate jail cells both confess even though they’d get lighter sentences if both stayed silent. The problem is that, as with the American electorate, they can’t coordinate their decisions. So it’s safer to confess and get a moderate sentence than to stay silent and run the risk the other person will spill the beans to go free, resulting in a harsh sentence for you.
The coordination problem is immensely frustrating to minor-party candidates such as Gary Johnson and Jill Stein, who are repeatedly told that voters don’t want to waste their votes on them. Nice, huh?
It also irks an even darker horse, write-in candidate Laurence J. “Larry” Kotlikoff, who has the additional burden of being a Ph.D. economist, which means he knows game theory inside and out. A Stein or a Johnson, or a Kotlikoff, for that matter, could still win the presidency if something truly enormous happened that lifted him or her above the fray and made the candidate less of a waste. But what could possibly do the trick?
In an interview, Kotlikoff speculated that for him, getting an endorsement from Justin Bieber might just be enough. (He might have been joking.) Bieber has nearly 88 million followers on Twitter, though a lot of his followers don’t vote.
For more insight into the coordination problem, I e-mailed Beth Leech, a professor of political science at Rutgers University and the co-author, with Rutgers colleague Lee Cronk, of a 2013 book on the coordination problem, “Meeting at Grand Central: Understanding the Social and Evolutionary Roots of Cooperation.” The title comes from the idea that if you agree to meet someone in New York City but forget to specify where, going to the middle of Grand Central Terminal is a good choice.
Here’s what Leech wrote back:
Interesting question, Peter.