Why It's Always a 2 Party System
And What Can Be Reasonably Done
For just about the entire history of America, the federal government has been a two party system. First there were the Federalist and Democrat-Republican (Anti-Federalist) parties. Then these were both replaced by the Democrat and Whig parties. Then the Whigs were replaced around the time of the Civil War by the Republican party.
Since the Civil War, the two parties have been the Democrats and the Republicans. This is true even today, when Gallup polls show both parties enjoy only minority support, with “independents” (not affiliated with either party) actually being nearly a majority in terms of self-declaration.
So then why is it so difficult for any third party to gain traction? Why, historically, have new parties only subsumed and replaced one of the two main parties, instead of adding to the number of parties able to reasonably vie for power?
Duverger’s Law
In 1954 Maurice Duverger, a French political scientist, proposed the hypothesis that is now called Duverger’s Law:
“A simple majority, single ballot system favors a two-party system.”
By this, Duverger means that in an electoral system where you have just one round of voting, and the winner of the highest number of votes wins…in that voting regime you are likely to have a two-party system. This is what a good many countries have, and in most of those countries, there are only two major parties.
The reasons for this are fairly straightforward, but first I want to describe a little bit of terminology that will be useful..
First Past The Post (FPTP) voting - Whoever gets the most votes wins. This is the “simple majority” Duverger mentions1.
Single Ballot or Round - A single ballot means that if there are 2 or 4 or 47 candidates, a single vote is held and whoever get the most votes - even if less than 50% - wins. This is how most elections are held for congress in the US2.
2nd or Multiple Ballot or Round - After a first round of voting with many candidates, a 2nd round is held with the two winners going head to head in the 2nd round. In some cases multiple rounds are held, but most of the time it’s just two. France recently held such an election. Le Pen and Macron got the highest two vote totals in the first round, and so they were the only two candidates in the 2nd round, which Macron won.
So a restatement of Duverger’s law that I find useful (because “majority” is an ambiguous term) is:
Two-party systems are the stable and likely result in electoral systems with single-round, FPTP voting.
Why Is This?
The reason for this is that candidates of a widely-spread third party will have very little chance of winning any seats in an election. If the support of a strong-ish third party is on average 20% over all of America, then in a FPTP election, candidates from that party would on average get 20% or so of the vote. The candidates for the other two parties would be vying for the remaining 80% of the vote, and no matter how that 80% is split up, one of the other candidates will always get way more than 20% of the vote. So the third party candidates won’t end up with 20% of the seats in Congress, but rather very close to 0% of the seats.
It is important to note the adjective above “widely-spread.” If a third party were very strong in a small region particularly, then they would win the seats in that region. This is the case in many countries, but not typically in America, whose population is politically quite homogenous. Even in the reddest or bluest states, populations are usually split 60-40 between the two major parties, or at most 70-30.
This has a reinforcing effect, because even though most people don’t have a formal understanding of Game Theory3, almost all of us live it out. Even if 20% of the population agrees more with the third party, they know that their vote will be going to someone that is extremely unlikely to win. And while protest votes do get cast pretty often, most people will not vote for their preferred 3rd party candidate for the following three reasons:
They want to prevent the worst case scenario candidate from winning. This is why so many people say they are “voting for the lesser evil.” Really, they are rationally voting in a way that minimizes the chance that “evil” wins, in their opinion.
People like to be on the winning team. Humans may like to cheer for underdogs, but usually they don’t want to be associated with losers.
Propaganda - We live in societies that are awash in propaganda from Media and Social Media sources. Very rarely do 3rd or 4th party influencers have control of a major Media organization, and rarely do they successfully deploy Social Media talking points. One of the reasons that 3rd parties don’t exist is that the top two parties don’t want them to.
I mention the third reason above simply because it’s true, but it’s almost unnecessary because the effects of the first two points are extremely strong and can explain the existence of two party systems in single-vote FPTP electoral systems on their own.
What Can Be Done?
This blog is not partisan4, and I am not even taking the position that a strong third party is necessarily a good thing. I think it might be, and a lot of people seem to want there to be a viable third party, or to gain the benefits having a third party would bring. This analysis will be for the American system. There are ways to generalize this analysis, but as you will see we will be getting into the weeds, and such specificity may preclude direct application elsewhere.
This is a very steep hill to climb. I will rate each solution in two dimensions: Effectiveness and Likelihood. Effectiveness means that IF this solution were somehow implemented, how effective would it be in helping establish a multi-party system? Likelihood is the likelihood that such a thing could be implemented (passed into law or use) in the next 20 years.
Two-Round Voting
Every election for Congress would have two rounds. The first round would be all candidates, and the second round would be the top two candidates. This would instantly create strong demand for 3rd and 4th party candidates that in many places would at least make it to the 2nd round, and in more than a few cases win a seat. This would also cause the main parties to become more responsive to the issues raised by the 3rd or 4th party candidates.
It’s also possible that this might reduce the need for primaries within each party, but I doubt that would occur, as each party would want to put its best foot forward in the first round.
Effectiveness - This would likely still result in only small/moderate levels of power for smaller parties. But the effect would be significant, and would actually begin to have a chance to create caucusing power in congress, as a party with 10 seats in the house or even just 2 seats in the Senate can play kingmaker and thus extract legislative/policy concessions from one of the larger parties on certain issues.
Likelihood - 10% chance of wide adoption. As with most reforms mentioned here, this would have to happen at the state level, and all states are run by one of the two major parties (or both). I think we might see a few states adopt this, but this will take a lot of determined organizing and lobbying. The existing politicians will (rightly) see it as a threat to their parties. They will use the excuses of the extra expense and inconvenience of having double elections for each office to help stop such proposals.
Ranked Choice Voting
Ranked choice voting has each voter pick not only one candidate, but also their 2nd and 3rd choice. If no single candidate receives a majority of the “First Choice” votes, then the candidates that received the fewest first choice votes are eliminated, and the voter’s 2nd choices come into play. A voter that voted for a weak candidate as their first choice now automatically has their vote “switched” to the stronger candidate. This automatic elimination continues until one candidate receives the majority of the votes5.
The benefit here is that you only have one physical round of voting, but there are two or more actual rounds, and they happen instantly and automatically.
Effectiveness - The effect would be significant and almost exactly the same as the effects of two round voting, with smaller parties actually having a chance to get into congress and be wooed by the larger parties. There would be more opacity in the results, and many people would be confused and perhaps angered by the complexity of how the instant multi-round system works, especially at first.
Likelihood - 25% chance of wide adoption. Again, the large parties will fight this, and it will take a groundswell of support and lobbying to get implemented state-by-state. I try to never use Wikipedia as a source, but its article on Ranked Choice Voting summarizes the current state of already-implemented ranked choice voting in the US so well that I couldn’t resist:
Ranked-choice voting is used for state primary, congressional, and presidential elections in Alaska and Maine and for local elections in more than 20 US cities including Cambridge, Massachusetts; San Francisco, California; Oakland, California; Berkeley, California; San Leandro, California; Takoma Park, Maryland; St. Paul, Minnesota; Minneapolis, Minnesota; Santa Fe, New Mexico; Portland, Maine; Las Cruces, New Mexico; and St. Louis Park, Minnesota.[1] New York City is the largest voting population in the US using Ranked Choice Voting.
I think Ranked Choice Voting is perhaps our clearest path toward true viability of third and fourth parties. And it’s already being used or has been used in a lot of American states and cities.
Federal Election Law Changes
This won’t happen for two reasons. First, people in power like things they way they are. Second, Federal oversight of how elections are run is fairly limited. States have that responsibility, not the federal government. You would have to change the Constitution in order to do this.
Effectiveness - negligible
Likelihood - close to 0%, because elections are held and run by the states.
Constitutional Amendments
So then of course we could change the Constitution to, say, require Ranked Choice voting. But again, the bar is so high to get a Constitutional Amendment passed (3/4 of the states after passing 2/3 of both houses of Congress or a special delegation of Congress) that I think it would never happen.
Effectiveness - depends on the Amendment, but potentially very strong.
Likelihood - Next to 0%. The goal to get everyone to agree to lose power is a fool’s errand.
So….I also want to mention my own idea. Because remember, the goal of a lot of people that want third parties is not necessarily to have third parties, but to increase the representation of viewpoints, to actually turn those desires into legislation. Currently, fringe ideas don’t even get a vote.
Whichever of the two parties is in power has tremendous control over which legislation even gets voted on. This is controlled in two ways. First, the majority party in each house controls the committee assignments, and of course they make sure their party has a majority on each committee. If the committee votes that a pieces of legislation will not be considered, it almost always won’t be. Second, the leader of the house and the leader of the senate decide when and which legislation is voted on, a second gate to block voting on legislation held solely by the majority party.
Rule Change - Every Lawmaker Gets a Vote On Their One Bill
The best simple rule change I can think of to create more politically diverse sets of legislation onto the floor is that every member of the House of Representatives gets to call a vote on one piece of legislation every term (2 years). Also, every member of the Senate gets to call a vote on three pieces of legislation every term (6 years). This way each member truly gets a voice with no gates. I think it should also be a requirement that each bill be a standalone vote. No riders, and not attaching it to larger bills.
A Senator can pair with a House member to get the Legislation all the way through congress, even if they are in the minority, if their bill passes. People can protest or ask their congressperson to put forth a bill, and those members can run on the fact that they listened and at least tried. More diverse and more personally responsible legislation will be produced. The more chances we have to get ideas directly from the people through just one representative and not other gates to at least get voted upon, the better. This more direct representation will give us a lot of the benefits we might enjoy if there were more parties, with none of the possible detriments.6
This could be introduced itself as legislation, or simply adopted as a rule change, or even an unwritten tradition. I think this is actually likely to pass because it empowers each individual congressperson in a way I think they would find exciting.
I don’t really know what the Effectiveness or Likelihood of this idea would be, but it seems like it would be a lot of fun. Or horrible. Which would still be fun.
First Past the Post voting is the technical name for the voting system most used in the United States. The name derives from horse racing, it refers to the horse that first crosses the finish line or post. Technically it isn’t a majority rules but a plurality rules system. Whoever gets the most votes in an election wins, even if it is much less than 50%.
The United States is a minority for its almost exclusive use of single round, FPTP voting. Most countries use some type of proportional system.
Game theory is a branch of mathematics that studies optimal strategies for a particular set of rules, a game. The game theory for First Past the Post voting is simple and results in votes for only the top two candidates. CPG Grey has a great explainer video on illustrating the logical progression, that leads to two parties.
Except that it opposes the evils of Communism, Fascism, and Daylight Savings Time.
What is described here is a subtype of Ranked Choice Voting called Instant-runoff voting. While RCV technically refers to a family of voting systems. In practice when you see a voting system referred to as RCV it is using instant-runoff voting rules.
I am not saying there ARE necessarily detriments to there being more than two viable parties, but I guess there could be?