Plurality voting

Plurality voting is the most common voting system used today. I’ll explain it here, but you already know how it works. You might not have a name for it yet. I’m calling this Plurality, but other names are used such as first-past-the-post.

In Plurality voting, voters mark one candidate on their ballot. Once all ballots are collected, counters add up the numbers of ballots that “vote for” each candidate. The candidate with the most votes wins the election.

Yes, people often gripe about this method. I do, too. The one thing every electionologist agrees on is that Plurality is bad. But what does that mean? How bad is it, and in what ways?

Other articles here will go into more details. But here are some highlights:

• Plurality is one of very many possible voting methods. It is not the only way to vote on things.

• Plurality is significantly worse than nearly all other voting methds, and by every measure…

• Except when there are exactly two choices to consider: a two-candidate ballot. A Yea-or-Nay vote. If you have only two choices, almost all voting methods give the same result as Plurality. They all become equally good.

• There are two major defects with Plurality:

  • A spoiler effect — when a relatively unpopular candidate is on the ballot along with a more popular candidate that shares similar positions and attracts some of the same voters, both of those candidates have a harder time getting elected. Independent candidates hurt their own causes.
  • A center-squeeze effect — Plurality rewards candidates toward the fringes of a political spectrum, so to speak. Candidates do unreasonably well whose supporters are unlikely to pick anyone else on even a crowded ballot.

• Plurality voting, over time in politics, leads to:

  • A two-party system. This is Duverger’s Law. The spoiler effect tends to stunt the growth of third-party movements. I’m not saying that Plurality is the only reason for two-party systems where they occur, but it’s an important contributing factor.
  • Divisive representation. The center-squeeze effect makes it difficult for centrists to get elected. In US politics, this is particularly severe in primary elections.

What methods are better worse than Plurality?

Of all the voting methods I’m aware of, only one method does worse when stakes are high: Borda. For well-known reasons, people don’t use or recommend Borda. So just ignore that or other hypothetical voting methods like anti-plurality (the winner has the fewest dislikes).

To get better election results, all you have to do is use a different method!

That said, the second-most-popular voting method, which again goes by many names, is only marginally better than Plurality. I see no reason to go to the trouble of replacing the worst voting method with the second-worst: Instant runoff. There are many great choices of methods! Pick any one! But not Plurality or Instant runoff. I’m quickly getting off-topic now, but Bottom-Two Instant Runoff is a big improvement over IRV in every way.