Plurality voting: Advantages?

Question

Context:

I'm a 1st time voter in a plurality voting state. As part of deciding how I'm going to vote, I'm trying to know what is the intention of a state choosing plurality vote (I'm assuming they all have the same intention if the voting system is essentially the same). I'm guessing that a state's reasoning for picking a voting system is deduced from the advantages of that system.

2 questions:

1. There's a whole list of disadvantages on Wikipedia; However, what are the advantages?

Not just advantages as in lower cost, e.g. less time spent on voting, counting votes, etc. I mean advantages as in the actual benefit (if any) of doing this kind of system specifically over other systems? i.e. what's the additional revenue (if any) besides the reduced cost?

2. There's an example given 'Imagine that Tennessee is having an election on the location of its capital', where 58% people prefer Memphis least but Memphis wins. What exactly can be the moral lesson(s) here for voters?

I really mean to ask for voters because obviously it's not like we're gonna change system anytime soon. (Based on the answer to (1), maybe the system doesn't even need to change!) A lot of what I'm reading online speaks more to people who are designing voting systems rather than to people who are voting (in plurality voting systems).

Anyway, I guess it's something like 'don't be stubborn/picky'. And I don't mind not being stubborn/picky. I think of a legal analogy: If I'm part of the defense, then I'll gladly settle with the prosecution instead of going to verdict. But the analogy doesn't quite tell me what to do when there are 3 or more prosecutors. (I think 2 prosecutors is ok. 1 prosecutor of course is the 2 candidate thing, with the other candidate as going to verdict.)

What I've also read:

1. There is a little what I read that does speak to such voters namely it's not enough just to vote tactically (like listen and read to what others have to say and then make our choice) but that we must also speak up ourselves about the person we are tactically voting for...or something. (Perhaps this kind of answers (1) like the/an intention is for people to speak up. Otherwise, say in ranked votes, people will just be quiet or something.)

2. Something else I'm reading says plurality voting could be objectively bad, but it's tough to change the system...does this mean to say there isn't (necessarily) a particular moral lesson (for voters)? Eg vote whatever and just...not exactly let the voting system correct itself, but let the politics correct itself to become 2 party?

Answer 1

The primary advantage of such systems is their conceptual simplicity. I don't have to spend an hour explaining the mathematics of "first past the post" systems to you, I can do it in a single sentence:

Whoever gets the most votes, wins.

The strategic space is profoundly (arguably problematically) simplified and the results are clear extremely quickly. This allows decisions to be made with a measure of authority and avoid lengthy challenges. If you think the recent history of the United States (Bush v. Gore onward) says otherwise let me offer: it could have been much, much worse.

That simplicity also does a decent job at moving the system away from radical change, and towards incrementalism. Stability is often viewed as a positive thing for the smooth operation of a society - especially for those who benefit from a given status quo - and so is considered an advantage of this kind of system. By edging out third parties, you also edge out minority voices until such a time as they can form pre-election coalitions.

As to your #2, I hesitate to call it a 'moral lesson,' but the main takeaway is that when you live in a plurality jurisdiction it is incredibly important that you correctly answer the question that is meaningfully being asked of you. In the main election, when you're standing in the ballot box, you're being asked to choose from one of two candidates - whoever is in front, and whoever is closest to that person and thus has any hope of catching them at all. Regardless of the list of names on the ballot, those are the only two positions that matter in a plurality election; so mathematically those are the two candidates you're being asked your preference on. Any other answer (vote) is meaningless in that moment.

This isn't to say that there isn't room for third party politics in plurality systems - just that the ballot box is not where those types of work have traction.

The goal of a third party in such a system is to grow its base of support without drawing support away from it's closest ally of the current two top parties, until such a time as it is able to meaningfully displace one or the other. At which point, it is now one of the two ascendant parties.

Basically plurality systems take the forces that play out in the parliament of proportional representation systems and have them play out prior to the main election, instead. In the parliamentary system, you form your coalition after the election is over. In plurality systems, you need your coalition in place before the first vote is cast.

Answer 2

Simplicity and history:

Plurality voting is easy to explain and implement.

And so it was implemented first.

And once it was implemented, everyone got used to it.

And once everyone was used to it, nobody wanted to rock the boat for fear of the unknown.

Also, the people currently steering the boat like the boat as it is.

So, when you say:

I'm guessing that a state's reasoning for picking a voting system is deduced from the advantages of that system

You guess wrong. The founding fathers did not engage in a lengthy discussion comparing the merits of different voting systems. And once a system was established, and the authority to change that system vested in the system itself, the people in control of changing the system were precisely the people most owed their success to the old system, and thus had the most to lose from changing it.

Looking at the history of my own nation, plurality voting was not replaced by an act of representatives elected under the old system. Fortunately for Switzerland, constitutional changes are decided by popular vote rather than an act of parliament, and the change passed, to the astonished surprise of the majority parties, who lost greatly in the next election.

Answer 3

Plurality (or "First past the post" or "FPTP") is Precinct Summable and Hare RCV (a.k.a. "IRV") is not precinct summable. I guess you could call that a reason to use FPTP. But Condorcet RCV is precinct summable.

Precinct Summability is a property of a voting system that makes it possible for each voting precinct to print out voting tallies for that precinct only and then post those tallies at the precinct location immediately after the polls close so that outside parties (like the media or the various campaigns) can observe and record those precinct tallies and total them up independently of the central authority and see who wins the election. It's about process transparency and decentralizes the task of tabulating results.

Please read about this in my recent paper about RCV and Burlington 2009.

Answer 4

There are no substantial advantages of first-past-the-post voting (which generally requires only a plurality to win in contests with more than 2 candidates). FPTP voting is simple, yes. But so is approval voting. And score voting is also quite simple. By contrast, FPTP often requires manual runoff elections, which double the complexity and cost of elections.

FPTP also has the spoiler effect which generalizes to a 2-party system. It leads to more extreme candidates being elected than in other systems, because only a fervent plurality is required to win. It tends to leave those that aren't part of the majority completely unrepresented, which makes it ripe for being abused by gerrymandering, which in turn cranks the extremist candidates up a few more notches (since the majority party can capture a jurisdiction, shifting the center of possible winners in the direction of that extreme).

FPTP when analyzed using bayesian regret comes out the worst among any comparable voting system:

FPTP fulfills almost none of the many voting criteria, fulfilling only:

• Majority (if more than 50% of the voters prefer a candidate, that candidate will win)
• Monotonicity (giving an additional vote to a candidate can't cause them to lose),
• Participation (very similar to Monotonicity),
• Consistency (if a candidate wins by votes of two separate sets of voters, the candidate will always win if an election is held with voters from both sets).

Notable criteria FPTP does not fulfill:

• Majority loser. If more than 50% of voters prefers every other candidate to candidate A, candidate A might still win in a FPTP vote.
• Clone proof. If a similar candidate to the candidate that would win is added to an election, in FPTP the formerly winning candidate may not win (and will in fact be extremely likely to lose). This is the spolier effect.
• Favorite betrayal. In FPTP, voters regularly have large incentives to vote against their favorite candidate if their favorite candidate isn't one of the two predicted frontrunners.

The only thing keeping FPTP around is tradition and ignorance of the enormous harm FPTP does as a voting system.

The argument that FPTP is better because its simpler to explain is false for some voting systems, and irrelevant otherwise. Its the lazy argument for not rocking the boat made by people who can't be bothered to think about it.

Answer 5

Another advantage, besides being conceptually simple and avoiding complex coalition-based governments, is that's it's a "one vote system".

To take a counterexample, French presidential elections are run in 2 phases:

• pass 1, all candidates take part. If any one candidate gets more than 50%, they are considered to have an absolute majority and win.

• pass 2. If no one won in pass 1, the top 2 have a go at it and top person wins.

Now, taking the 2017 election, this is roughly what happened:

• Extreme left, Melenchon 19%
• Center-right, Fillon, 20%
• Extreme right, Le Pen 21%
• Center, Macron 24%
• rest...

Now, imagine that the 2 extreme candidates had gotten 20% and 20% and everyone else had had lower scores. That's not a big stretch when you have many politicians fighting on center-left/center/center-right and a dozen candidates all in all.

People would be forced to pick in the 2nd round between an extreme left and an extreme right, with presumably 60% of the electorate being extremely unhappy with the outcome.

The wikipedia article, like many articles on the subject, revels in shooting down this type of plurality voting, but usually fail to mention how alternatives also tend to have their own problems.

Is it perfect? No. But it's not necessarily as bad as opponents make it out to be.

I recall a game theory book I read that explained that no one voting system is going to reflect everyone's preferences.

Answer 6

There are two main advantages. Firstly, (as already mentioned) FPTP is simple to count. While there are practical advantages, the theoretical advantage is that there is only one reasonable way to count single-vote ballots. This contrasts with (for example) ranked ballots, for which there are multiple reasonable ways to count them (IRV, Borda Count, and several Condorcet methods that differ in details). It is common (as in the 2021 Alaskan election) for the IRV to differ from the Condorcet winner. This creates doubt in the mind of the voters that the "right" person was elected. If the same votes could be counted differently, it seems that the counting method is determining the winner, not the voters. (The same could be said for approval voting, which shares many of the benefits that FPTP has).

Secondly (and I believe this point hasn't been made yet) in a multi-constituency election, FPTP has a leverage effect: A party that wins a plurality with (say) 40% of the vote is likely to gain a majority of the constituencies. In the Westminster system, this means that the party will be able to control Parliament without forming a coalition.

Why is this an advantage? Systems that lack this leverage will tend to produce hung Parliaments, and then the choice of who becomes Prime Minister becomes a matter of negotiation after the election, with the voters having no further say. FPTP is one of only a few systems that have a strong leverage effect.

Now the advantages for majorities are debatable. But they do mean that a government can enact their manifesto. In a system based on coalition, it is normal that the government will have to compromise on its manifesto, ending up with a mix of policies lacking a clear ideological basis. Moreover it tends to mean that governments can last for a full term (four or five years perhaps), and then be judged on what they have achieved. Of course, FPTP doesn't guarantee majorities, but it does make them much more likely.

These two points together give what is seen as the advantage of FPTP: It is a system in which the link between votes and a change of government is particularly strong. There is a simple clear relationship between the votes as cast and the winner of each constituency election, and little argument about how the votes can be counted. There is leverage that magnifies a plurality to a majority.

A minor advantage is that the leverage effect tends to mean the parties that are unpopular with much of the population, tend to be squeezed out. Extremist parties often have small numbers of fanatical supporters. In the FPTP system, such extremist parties will not get any representation in Parliament. For example, the racist NF and BNP has had support of several percent of the population, but was never close to winning any seats in Parliament. This is probably a good thing. This blocking of minor parties occurs without arbitrary mechanisms like a 5% threshold (which would beg the question "why 5 and not 1 or 10?")