JDN 2457465

As I write, Bernie Sanders has just officially won the Michigan Democratic Primary. It was a close race—he was ahead by about 2% the entire time—so the delegates will be split; but he won.

This is notable because so many forecasters said it was impossible. Before the election, Nate Silver, one of the best political forecasters in the world (and he still deserves that title) had predicted a less than 1% chance Bernie Sanders could win. In fact, had he taken his models literally, he would have predicted a less than 1 in 10 million chance Bernie Sanders could win—I think it speaks highly of him that he was not willing to trust his models quite that far. I got into one of the wonkiest flamewars of all time earlier today debating whether this kind of egregious statistical error should call into question many of our standard statistical methods (I think it should; another good example is the total failure of the Black-Scholes model during the 2008 financial crisis).

Had we trusted the forecasters, held our noses and voted for the “electable” candidate, this would not have happened. But instead we voted our consciences, and the candidate we really wanted won.

It is an unfortunate truth that our system of plurality “first-past-the-post” voting does actually strongly incentivize strategic voting. Indeed, did it not, we wouldn’t need primaries in the first place. With a good range voting or even Condorcet voting system, you could basically just vote honestly among all candidates and expect a good outcome. Technically it’s still possible to vote strategically in range and Condorcet systems, but it’s not necessary the way it is in plurality vote systems.

The reason we need primaries is that plurality voting is not cloneproof; if two very similar candidates (“clones”) run that everyone likes, votes will be split between them and the two highly-favored candidates can lose to a less-favored candidate. Condorcet voting is cloneproof in most circumstances, and range voting is provably cloneproof everywhere and always. (Have I mentioned that we should really have range voting?)

Hillary Clinton and Bernie Sanders are not clones by any means, but they are considerably more similar to one another than either is to Donald Trump or Ted Cruz. If all the Republicans were to immediately drop out besides Trump while Clinton and Sanders stayed in the race, Trump could end up winning because votes were split between Clinton and Sanders. Primaries exist to prevent this outcome; either Sanders or Clinton will be in the final election, but not both (the #BernieOrBust people notwithstanding), so it will be a simple matter of whether they are preferred to Trump, which of course both Clinton and Sanders are. Don’t put too much stock in these polls, as polls this early are wildly unreliable. But I think they at least give us some sense of which direction the outcome is likely to be.

Ideally, we wouldn’t need to worry about that, and we could just vote our consciences all the time. But in the general election, you really do need to vote a little strategically and choose the better (or less-bad) option among the two major parties. No third-party Presidential candidate has ever gotten close to actually winning an election, and the best they ever seem to do is acting as weak clones undermining other similar candidates, as Ross Perot and Ralph Nader did. (Still, if you were thinking of not voting at all, it is obviously preferable for you to vote for a third-party candidate. If everyone who didn’t vote had instead voted for Ralph Nader, Nader would have won by a landslide—and US climate policy would be at least a decade ahead of where it is now, and we might not be already halfway to the 2 C global warming threshold.)

But in the primary? Vote your conscience. Primaries exist to make this possible, and we just showed that it can work. When people actually turn out to vote and support candidates they believe in, they win elections. If the same thing happens in several other states that just happened in Michigan, Bernie Sanders could win this election. And even if he doesn’t, he’s already gone a lot further than most of the pundits ever thought he could. (Sadly, so has Trump.)