The Two Party System for Dummies

I'm writing this article to answer the complaint that "the two major parties look virtually identical". In my view, yes, the major parties are virtually identical, and this is a good thing. It's a healthy sign in a two-party democracy. I think that a misunderstanding about how democracy works is causing people to become disillusioned with a system that is in fact working perfectly.

I have two basic points:

First, I don't believe that modern western societies can reasonably be divided into political classes. Whether it's "ruling class" and "working class", or "liberal" and "reactionary", or "left-wing" and "right-wing", or however you want to divide things up, you'll find that actually the biggest category is people who are "sorta halfway". On any particular issue, say abortion, or legalisation of marijuana, or immigration, then if you speak to a random group of people you'll find that their opinions form a continuum. They won't neatly divide themselves into "for" and "against" camps.

My second point is that our two-party democracy is still a one-party government. It's not much use having a nice balance of one left-wing party and one right-wing party, because one or the other is going to have to be elected, and then the government itself will be hopelessly unbalanced. What you really want in charge of your country is a compromise party. If both parties start competing to be the best compromise party, then voila, you've got two parties that end up being practically identical.

To demonstrate this, I'm going to run through a mythical sequence of elections between the "Social Democrat" and "Conservative" parties, in a non-existant country where they have first-past-the-post voting. This is the voting system used in the US and UK.

What do the people think?

I'm going to concentrate on one particular issue: what should the tax rate be? Now, your usual political surveys don't ever ask that kind of question. Usually they're just trying to get the result they want, and to do that they like to ask yes/no questions:

Do you believe that taxes should be:
  1. Cripplingly high, or
  2. Reduced to sensible levels, like it says in our party manifesto?

But if you really asked the question "How high should taxes be?", you'd find that the answers would form a normal distribution. If you've never heard of a normal distributions, it looks like this:

There are extremists on both sides: people who believe in zero taxation, and people who believe that property is theft and everything should be appropriated by the state. But the most popular opinion is also the one right in the centre.

This isn't necessarily how things are - sometimes public opinion really is polarised into two distinct, diametrically opposed camps:

But that's rarer than people think. Human beings like to make categories, and we're good at it - it helps us make sense of the world. But we also have a tendency to extrapolate that labels like "left-wing" and "right-wing" actually exist, as discrete objects, in the real world. I believe that this is the mistake that leads people to believe that political parties should have strong, idealistic roots. The following analysis will try to show that in fact, that's the last thing they should have.

The two party system

So now an election's coming up, and let's say that the big deciding issue is the level of taxation. In a real election, there are dozens of big issues operating simultaneously, but just for this analysis I'll assume that taxation is far far bigger than all the others. We can show the opinion of each of the two parties on the graph. To start with, let's put them in traditional "left-wing" and "right-wing" positions, and with the Social Democrats in a slightly more extreme position than the Conservatives:

During the election, people are going to vote for the party whose opinion is closest to theirs. Extreme left-wing voters will vote for the moderately left-wing Social Democrats, while extreme right-wing voters will vote for the moderately right-wing Conservatives. In the middle, we can draw a line exactly half-way between the parties' positions, and we can say that everyone to the left of that line will vote Social Democrat, and everyone to the right will vote Conservative:

Note that this line is slightly to the left of centre. Practically, this means that some voters who are slightly left-leaning are being put off by the relatively extreme Social Democrat position, and find themselves actually having more in common with the right-wing Conservatives. As a result, the Conservatives win with a slim majority.

The Social Democrats go back and do some soul-searching. They still believe in high taxation, but pragmatically they recognise that going to the people with an extreme high-taxation platform is just going to result in them losing, and taxes falling still lower. They'll do some polling and find that actually most people agree that taxes should rise; they just wouldn't go as far as the Social Democrats have. At the party conference, speeches will be made about "recapturing the heartland" and "representing ordinary men and women just trying to make a living". And at the next election, they'll come out with a more moderate position, and win the election:

Note that this is good for the people. As a result of the Social Democrats' pragmatic change of heart, the government now has a policy much closer to what the people actually want. Also note that the Social Democrats still really want very high taxation, but they've implemented a moderate policy to win votes. You could call it "cynicism" or "hypocrisy" if you want, but it hardly matters. Who cares what philosophical constructs are floating around in the politicians' heads, as long as the opinion of the people is being respected? If the government ever goes back on their commitments and reverts to extreme ideological policies, they'll just get kicked out at the next election.

Of course, by the next election the Conservatives have figured out their mistake. They go through the exact same process as the Social Democrats, and by coming up with an even more moderate position, they get voted back in again:

Note that what's happened here is that the Social Democrats have, in a way, still won. They've forced the Conservatives to scale back their ideologically-driven right-wing agenda, and respect the will of the people. This process doesn't actually have to wait for two election cycles. Just by analysing each others' policy statements, and the reaction of the public, political parties can play many rounds of this game without having to fight a single election.

Over many many elections, each of the parties will be forced to make more and more compromises to get elected. The result should look like this:

There's hardly any ideological difference between the two parties; they're both crammed in together in the middle ground. Each is desperately trying to squeeze that tiny little extra bit of precision out of their polling to figure out precisely where to place their policies. Or to put it another way, both parties are stretched to the absolute limit of trying to respect the will of the people. Which is what democracy is supposed to be all about. Therefore, I call this a healthy democracy.

What can go wrong?

As I said before, there's more than one issue that's important at any election. If the two parties spend all their time fighting over one issue, like taxation, they might "drift" on another issue. Consider the real-life example of Australia in the 90's. The two major parties were arguing about economic issues, which is how western two-party democracies all seem to end up. However, while they were so busy doing that, it seems that they were both leaning in a fairly liberal direction when it came to immigration, and this was out of step with the general opinion of Australians (just for the record, I should point out that my opinion on immigration is even more liberal than the major Australian parties; but I recognise that this opinion isn't shared by the majority of Australians). When this happens, it's an opportunity for a third party to come in and shock the system a bit, and in this case it was Pauline Hanson's "One Nation" party, and her radical anti-immigration policies.

Pauline Hanson's position was pretty extreme, and even at her peak she was only getting a small minority of support. However, she had a huge effect because she switched attention from the economy, where both parties had a really boring middle position, to immigration, where both parties were out of step with public opinion. Suddenly the game had switched away from the economic competition, and the major parties had to start again from scratch. Now, both parties have to compete to find the middle ground on immigration if they're going to win elections.

Note that Pauline Hanson herself doesn't have to play this game. She can stay as extreme as she likes. Her effect is just to ensure that there's a real variety of opinions being presented on the issue, so that attention focuses on the immigration question and the major parties are forced to move.

So yes, it's possible that the two parties can drift away from public opinion on some issues. In these cases it's the tiny, extremist, single-issue parties that can fix the problem. But you don't necessarily need these small parties in government. The old two-party institution will always perpetuate itself. Which again, is no bad thing.

The third party spoiler effect

Faced with the reality of a choice between two parties that are absolutely indistinguishable, most people get pretty sick of politics. They really want a little more choice, and sometimes this results in a third party joining the fray. Now as I said in the previous section, when they focus attention on some policy area that's been neglected, like immigration, this can be a good thing for democracy. But if they jump straight into the question that the major parties were already fighting over, then the result is that government policy actually starts to diverge from public opinion.

Let's say that it's midway through one of our election games, and the Social Democrats are currently winning by having a somewhat more moderate policy than the Conservatives. Into this mix comes the ideologically committed Socialists, with a rather extreme left-wing policy:

At the election, the Socialists clean up the extreme left-wing electorate, while the Conservatives take much of the middle ground as well as the extreme right. The Socialists take just enough of the vote away from the Social Democrats that the Conservatives end up winning. This is called the spoiler effect:

Note that the new government's policy is further away from the will of the people than it was before. This would have to be considered an unhealthy development for democracy. In general, when three parties are running, you would expect the centrist party to always perform the worst.

Let's assume that the Socialists aren't really concerned about getting into government, and that they remain firm in their ideological commitment. The other two parties are left to carry on their game as before. But now the extreme left isn't a factor, whereas the extreme right is still worth fighting over. As a result, the stable situation after many elections looks like this:

Both major parties are now to the right of the general population. There's no reason for either of them to move to the centre; if they did, their opponents would win the whole of the right while the Socialists would take a big chunk of the left. By sticking to their left-wing position, the Socialists have actually forced the major parties to ignore the people and adopt right-wing positions! Again, this is an unhealthy democracy. However, this effect can be seen time and time again in real life. It's a problem whenever the extreme wing of any political spectrum coalesces around a single party who are more committed to their own ideology than to winning power.

The conclusion from this is that political parties should all be totally committed to obtaining power at all costs. Any party that comes along which shows genuine ideological commitment should be avoided like the plague.

That's really depressing; I hate you

It is kinda depressing, I agree. The system does work, and it produces governments which genuinely try their best to reflect the will of the people. But the people are bound to end up pretty cynical about, and uninterested in, politics in general. That's no good, because politics is a really big deal and we should care about it.

There are two ways that I would suggest fixing it, both of which are in operation in Australia to a greater or lesser extent. They are proportional representation and preferential voting.

Proportional representation

In the first-past-the-post system used by the UK and US, the party with the most votes gets elected, while all the rest get nothing. Under these circumstances, there's no point representing a minority opinion, because you'll just get trashed at the election. In a proportional representation system, each party gets representation in parliament proportional to the number of votes it received. Parties which choose to represent minorities can still get elected and have a voice in the parliament. This cancels out the spoiler effect. Let's go back to the Socialists. After the election, the representation in parliament looks like this:

When it comes to choosing a Prime Minister, of course the Socialists are going to vote for the Social Democrat nominee. So even though the Social Democrats got less votes than the Conservatives, they still win the day. And that's a much better reflection of what the people really wanted.

Over time, more and more parties should join the fray. There will still be centrist parties trying to get their nominee elected Prime Minister (quite possibly more than two), but there will also be lots of extremist or special issue parties filling out the political lanscape:

This political system is used in Israel, for example. One noticeable problem, unfortunately, is the instability of the resulting governments. Israeli governments seem to be constantly trying to rebuild coalitions so they can stay in power, instead of governing effectively. All it takes is one tiny coalition partner to pull out and the whole government collapses.

Preferential voting

This is also called " instant-runoff voting" in the US. In this system, you don't vote for just one candidate, but rather number all of the candidates in your order of preference. All the first preference votes for each candidate are counted, and the candidate with the least votes is eliminated. Then, all of their votes are redistributed to the remaining candidates according to the second preference. Again, the one with the least votes is eliminated, and their votes are redistributed according to the next preference (which will be either their second or third preference, depending on whether the second preference was the candidate who's already been eliminated). This keeps going until there's only one candidate left; that's the winner.

This also eliminates the spoiler effect. People who vote "1" for the Socialists will almost certainly vote "2" for the Social Democrats. The Socialists will be eliminated early on, and all their votes redistributed to the Social Democrats. The Social Democrats win even though they have less first preference votes than the Conservatives.

Unlike proportional representation, preferential voting doesn't give the Socialists any official representation in parliament. However, it does allow them to use their support directly in negotiation with the government. They can go to the Social Democrats and threaten to instruct their supporters to put the Conservatives ahead of the Social Democrats, unless the government makes some concession to them. This has been used to good effect by the Green party in Australia.

How the US Two-Party System Is Broken

Looking at the current state of US politics, the remarkable thing that jumps out at you is how deeply ideologically divided the two sides are. And how much they hate each other. When you watch Australian politicians on TV, they might well call each other names when they're in the House, but you know that behind the scenes they just consider themselves as one big group of colleagues. But American politicians don't work like that. You choose a side, and the other side are demons. They're murderers, traitors, America-haters. Rhetoric is strong all over the world, but in the US not only is it especially vicious, but they really mean it.

According to the theoretical model laid out above, this should never happen. Over time, the members of each political party should migrate towards a common ideology. And when they do so, and meet in the middle, why wouldn't they be friends? This does seem to happen in Australia, the UK, Germany, basically everywhere. But not in the United States. Why?

I believe the reason comes down to the primary system. And I have more graphs to explain the problem.

In most countries, the candidates for an election are chosen by a small group of party hacks, in secret. They figure out which candidate is most likely to get elected, and then they arrange for the party to support that candidate. It's all carefully stage-managed from behind the scenes.

In the US, they hold a public election, in which all the party members can vote, in order to choose which candidate will go to the main election. So a candidate has to win two elections in order to win, not just one. And the problem is that the electorates in each election are very different.

You become a candidate for a political party for just one reason: you want power. This is perfectly natural and nothing to be ashamed of. With few exceptions, politicians want power so that they can do good in the world. But power is what motivates you, and so you'll cheerfully sacrifice ideology in order to get it.

People who merely join a political party are a different story. They will never achieve power, so there's no incentive for them to sacrifice their ideology to chase after it. They are motivated entirely by ideology. They might not be especially extreme, but there is clear space between their opinions and the "average" opinion of society at large. They care a great deal about what they believe in.

So the distribution for members of a particular party looks very different to the normal distribution for the general public as a whole:

Obviously an election conducted within an electorate like that is going to lead to results that are skewed to one side. Maybe there are two "wings" of the party, the left and the right. If so, the results would, theoretically, look like this:

In reality, things aren't so skewed. Party members aren't completely stupid. They know that they are going to have to compromise a little bit if the candidate they choose has a hope of winning the main election. Nevertheless, for an ordinary party member, there's simply no point electing someone if they're just going to be exactly the same as the guy who's there now. And most party members will overestimate their ability to convince the general public to vote for their guy. After all, nothing wins an argument like being right, right? Objectively speaking, they're certainly wrong, but if they understood that they wouldn't be a party member.

So maybe the result really looks something like this:

There's compromise there, but the natural bias of the party electorate keeps the curve permanently shifted to one side.


Here's the Wikipedia article on this subject.


Matthew Exon
Last modified: Mon Dec 24 10:19:19 CET 2007