The two major political parties seem to both be moving away from center (the Democrats seem to be lagging behind in this race to the outside but seem determined to catch up). But if we assume that individual political leanings are normally distributed, most people should be moderates with few people at either end. I do not know if this is true; the distribution could be bimodal, for example, with a conservative hump to the right and a liberal hump to the left.
But it still seems logical that there are more moderates than far-left or far-right. Why don’t both parties approach the middle more closely to get more voters?
(I’ll concede this may belong in IHMO but please let’s not turn it into a fiery GD.)
One problem in the USA is the primary system. The more common voters in the primaries are the more dedicated ones, so more likely on the extremes. This effect is magnified in Caucus states - more dedication is needed to take a half-day or more to participate instead of filling in a ballot. With the more dedicated, fanatical voting, it tends to emphasize the more extreme candidates, and candidates have to pander to those to win the primaries. Then the USA has the two-party system - so once the candidate is chose, the middle/moderate types have to choose between two extremes.
Contrast that with, say, France where four major party-groups put forward candidates and the two highest winning go to a run-off. Pandering to the extreme often does not work well as there is someone slightly more moderate to appeal to those middle voters.
Don’t know how aware American dopers in general are of the finer points of current British politics, but our two main parties have also lurched to the left and right extremes; but one effect of this has been defections of members of parliament from both to a currently coalescing new party in the middle ground. Numbers of MPs are currently small, but things are so unstable at the moment that three-figure membership by mid-March would not surprise me.
I guess this only makes sense if they believe that most (or many) voters remain in the middle ground - though there are major convoluting factors currently in play (the B word) which make things mighty hard to interpret clearly at the moment.
I am not a political expert, but I’m going to suggest that there are actually MANY normal distributions at work here and they reflect different issues. It’s tempting to think that there is one quality (such as “conservatism”) that you can represent on a single graph, but this is a bit simplistic. A typical voter is a lot more complex than that. In fact, it might be that the distribution you want to work with is one that shows “complexity of views.”
My opinion is that those in the so-called middle are more apathetic than politically moderate. ‘They’re all crooks!’ ‘Both sides are the same!’ They claim to be moderate because they have no opinions on anything.
And then there are people who are extreme on all of the issues, but extreme in different directions on different issues. Someone who believes in no abortions anywhere for anyone and no guns anywhere for anyone is probably going to prefer both an all-guns, no-abortion candidate and a no-guns, all-abortion candidate over a candidate who’s moderate on both issues.
I believe the answer is in an error in your premise. While certainly the population of all individuals in the US has to tend toward a Gaussian distribution-all large groups will tend that way, that isn’t the important group. What you need to look at is the distribution of chronic voters. Those are two independent groups. No appeal to one will have any effect on the other. So every successful message is aimed at one or the other group. Appeals to moderation aren’t successful if the other side has a strong get-out-the-vote message. In sum, the combination of relatively unmotivated group + some fraction of whatever moderate vote there is rarely equals the size of the highly motivated group. And on top of that party affiliation matters. Sure some people cross-over, but not many. The most the other party (doesn’t matter which one) can hope for is instead of cross-over the other parties voters stay home.
Why are ratings on products/restaurants/etc. not a normal distribution of 1, 2, 3, 4, 5 stars? Because the only people that leave feedback are people that are passionate about the item being reviewed and they either love it or hate it.
People pick up their political beliefs from their community, which is going to lead to some kind of n-modal clustering where there are some number of stable nexuses of beliefs that have some kind of cohesiveness. This can also lead to a clustering political positions that don’t really seem to have much of an obvious link, which further entrenches the modes.
The change in the landscape of information distribution is likely having an effect.
In the fairly recent past there were relatively few main sources for national information, and they were stable institutions that didn’t want to rock the boat too much, which led to national politics having a more centrist gentlemanly moderate quality. That is not much the case any more.
Evidence suggests that the role of the community does not account for a large amount of people’s political views. For example, this article finds that shared environment is usually the least important factor when explaining the difference in political views between people. Genetics and non-shared environment play a much more important role. In this case, shared environment are those non-genetic things which make twins more similar to each other, and non-shared environment are things which make twins less similar to each other.
This is certainly very complicated, with lots of gene by environment interaction going on, for instance conservative people choosing to live in a conservative community. The results do suggest that the reason their kids are conservative is because their parents gave them conservative genes (whatever those happen to be) rather than because they grew up in a conservative community.
Anyway, that doesn’t do much to answer the OP’s question.
While that’s a common notion, more recent research tends to undercut the old blank slate/tabula rasa notion. Twin studies seem to point to a significant genetic component to many personality traits. That shows up in research looking at political ideology (liberal, moderate, or conservative) as well. Self identified ideology seems to be about 56% determined at birth. Applying an assessment quiz to determine ideology tweaks the correlation to 58%.
That still leaves plenty of room for clustering with community or learning your politics “at the dinner table” as the old saying goes. There’s also plenty of partisan positions that don’t neatly fit those general approaches. Parties can package positions on issues to highlight the aspects that best fit the underlying and innate dispositions of their supporters. Let’s not overstate the clustering effect though. The evidence seems to point to our politics not being an area where environment is the only factor. Environment isn’t even the dominant factor. A similarly sized or a little larger chunk of our individual political leanings is predetermined at birth. Clustering and community can only do so much when the slate starts off around half filled.