The 2016 Republican presidential primaries provide a stern warning for Democrats as they approach their 2020 primary season: When a large number of candidates enter primaries determined by plurality rule (our current way), a candidate who does not share the vision held by the majority of a party's membership can end up as that party's nominee. The large candidate field dilutes the preferences of the majority. To regain majority rule, the party should substitute instant run-off voting, also known as ranked-choice voting.
While there is considerable agreement among members of the Democratic Party on their list of priorities — health care, college finance, climate, etc. — there are different opinions about the best way to make progress on them. For many progressives, the best policies are single-payer health care, free college and rapidly phasing out fossil fuels in favor of renewables. More traditional establishment members favor reforming the student loan program, fixing the flaws in the Affordable Care Act, and taxing carbon emissions to make the energy market work more efficiently. These policy differences are substantial, so the party needs a voting protocol that will ferret out and promote the policy preferences of the majority of party members.
The problem of preference dilution is not ideological; it is arithmetical. In a three-way race, it is clear that third-place finishers draw votes from other candidates with whom they are most closely aligned. More generally, the likelihood of a policy preference being represented by the winning candidate will be smaller as the number of candidates campaigning on that view increases.
For example, suppose that 70 percent of party members hold establishment policy preferences, while 30 percent side with the progressives. Further, suppose that the there are 10 establishment candidates, but only two progressive candidates. Under plurality voting, the substantially greater dilution of establishment policy preferences increase the chance of a progressive candidate winning the primary, well out of proportion to the relative preferences of the majority of voters.
Instant run-off voting, by contrast, is designed to let primary voters pick both their preferred set of policies and their preferred candidate. If the Democrats do not switch to instant run-off voting, both of these preferences are likely to be ignored in their 2020 primary. Voters, in elections employing instant run-off voting, use a ballot that allows them to vote for a ranked slate of candidates, not just their first choice. When the polls close, voting machines tally the first-choice votes. Only if the top vote getter has a majority of the total votes cast is that candidate declared the winner. If not, then first-choice votes for the last-place finisher are discarded, and the remaining ranked votes on those ballots are distributed to the other candidates. If this second round of vote distribution produces a majority, that candidate is the winner. If not, another similar round is run, until a candidate gets a majority.
The defect in plurality rule is even more alarming when used in primaries, where one election influences the next one. The winner of the first primary in the series gains not only that election victory but also a first-mover advantage in the next election in the sequence. Not only does that winner gain delegates toward the total number needed to secure the party nomination, but that candidate also gains the support of more donors who are attracted by a winner. Pollsters will see a statistical bounce, and the media will happily report on the candidate's "momentum." Of course, one by one, losers will drop out, but by the time the number of candidates substantially dwindles, the delegate count accumulated by this candidate can be insurmountable, a pattern that Donald Trump enjoyed in 2016.
Einstein's probably apocryphal warning that "insanity is doing something over and over again and expecting a different result." Surely, Democrats must see how insane it would be for them to repeat the 2016 Republican presidential primary experience. They must recognize the urgency for immediate action, if they wish to nullify the distortion that the plurality rule will certainly wreak on their party's selection of a 2020 presidential candidate. It will take time and patience to convince each state's party leaders to switch to an instant run-off voting ballot.
William L. Holahan is emeritus professor of economics at the University of Wisconsin-Milwaukee. Charles O. Kroncke, retired dean of the College of Business at UW-M, is also retired from the University of South Florida. They are co-authors of "Economics for Voters.''