Game theory. If people vote for the party promising policies closest to (using whatever metric) their ideals, and there are only two parties, optimal strategy for each party is to move as close to the center as possible.
They wouldn’t lose voters with ‘extreme’ ideals because, if they decided to not vote, parties would counteract by moving towards the new center, which would be further removed from the ideals of those voters abstaining from voting.
How do you square that with the rise of the Tea Party and the Alt-Right? It seems like they've found that they can motivate people to vote by moving _further_ from the center, and the moderates continue to vote the party line of whichever party they prefer.
Alt-right or the tea party would lose an election against a center-line party, big time.
Motivating people with ‘extreme’ opinions from one side of the spectrum to vote moves the center, so it can make both parties move in that direction.
Let’s (in a very simplistic model) say we have 100 voters on a 1 to 100 scale, so centered around 50.5.
If, normally, the extremes of 1 to 10 and 91 to 100 don’t vote, the center stays at 50.5. Convince the 1 to 10 people to vote, and the center moves to 45.5, so the two major parties move in that direction, too.
There’s an assumption here that most politicians are willing to, somewhat, go against their beliefs in order to get elected. I think that’s true, and unavoidable in a two-party system (which, in turn, is hard to avoid in a system with “winner takes all” elections), but if it weren’t, parties can easily replace candidates that object to a course change with others that either have different ideals or are willing to sacrifice some of that a bit in exchange for their career.
> so it can make both parties move in that direction.
This is the opposite of what we’re seeing on the right. Centrist republicans have been pushed out of the party for not being conservative enough over the last 4 years, and primary candidates go out of their way to outdo each other in terms of conservative positioning.
Nobody seriously running on the right is trying to be a moderate Republican on the federal level because being a “RINO” is political suicide.
The opposite of your view is what is happening for both parties. It's laughable to look at Republicans and think they are moving to the middle. The democrats have partly moved to the middle (Biden being a great example). But in primaries, which have the most energized voters on both parties tend to get less people in the middle. In practice, in reality, it doesn't work that way. Also gerrymandering tends to make districts even more polarized.
66% of americans oppose government data collection. Obviously neither party is anywhere near the ‘middle’ and other political forces are driving what legislation gets passed.
> Game theory. If people vote for the party promising policies closest to (using whatever metric) their ideals, and there are only two parties, optimal strategy for each party is to move as close to the center as possible.
This theory requires either ignoring that voters may have a threshold at which they become disaffected or ignoring that political opinion may not be unimodal; if you consider both of those factors, that strategy ceases to be dominant.
In the real world, voters can become disaffected and abstain, and political opinion is often not unimodal (in the US it's closer to bimodal.)
What you describe is not what happened. Look at republicans who ended up with Trump and the base was pretty happy to move far away from the middle, demonizing black people and other minorities. This move from the middle energized a large part of the population in the us.
Primaries in gerrymandered districts weed out moderate candidates. Their goal is to win the majority in their district or state, so they can sometimes ignore all other parties.
They wouldn’t lose voters with ‘extreme’ ideals because, if they decided to not vote, parties would counteract by moving towards the new center, which would be further removed from the ideals of those voters abstaining from voting.