I think this phenomenon is the fundamental problem of any two-party system and is one of the issues in American politics. The "us vs them" feeling is a lot less strong when there are multiple parties. This feeling leads to more divisiveness in politics and eventually trickles down to the whole population.
No, the biggest thing we're missing in the fight against 2-party system is an actual representative voting scheme.
A first-past-the-post [1] voting scheme will always result in 2 parties (assuming it doesn't collapse into a single-party autocracy) due to the spoiler [2] 3rd party vote problem.
It's not psychology but basic probability math and game theory.
Why is not fixed? Because this is the cheapest way for the moneyed elite to both a) wield power, and b) prevent that power from getting concentrated (which could result in a powerful dictator who doesn't listen to them).
Although I agree with you that the plurality voting system (aka FPTP) is a big problem, I think your theory of why it isn't changed is silly and overlooks the very real difficulties.
One of those difficulties is that there isn't a clear winner among the alternatives. Approval voting, the STV(/IRV), and the Borda Count all have adherents, who disparage the other two.
Worse, none of them is perfect. For example, STV and BC are both susceptible to strategic voting. I recall reading about some municipality that decided to try STV. IIRC, in the very next election they had two competent but extreme candidates at opposite ends of the political spectrum, and a centrist generally regarded as less competent (and who got a much smaller number of first-place votes than either of the others). The electorate was so evenly divided that the centrist won; the voters were so upset with this outcome that they ditched the STV and went back to PV (plurality). Evidently they would have been happier with one of the two extremists, even though that would have been the "wrong" choice for almost half of them.
We could object that none of the three candidates was obviously a great choice, and that if voters really preferred their opposite-extreme candidate over the centrist, they should have voted that way. But it's easy to see why they didn't. We could also object that AV would have given a better result in this case, picking whichever extreme candidate got the most votes and ignoring a widely-disliked centrist. But STV tends to be an easier sell, perhaps because it maintains the notion of "one person, one vote". And finally, we could object that they were too quick to pull the plug and should have given STV another chance, having learned a lesson about the importance of finding competent centrist candidates.
But their conclusion was, they tried an alternative system and it didn't work.
I tend to favor AV personally, as it's relatively resistant to pathological outcomes, but have to admit that it has another problem: it's the least tamper-resistant. With PV and STV, the total number of votes counted shouldn't be greater than the number of voters. AV has a much looser and less useful bound: the total number of votes shouldn't be greater than the product of the number of voters and the number of candidates. That leaves a lot more room for manipulation. In a world where our voting systems are already not as trustworthy as they should be, this is a problem.
Range voting and approval voting are closely related; approval voting is just the limiting case of range voting where there are only two values on the scale.
My take is that range voting is useful when you have a relatively small number of voters, but once that number gets into the thousands, its advantages over AV fade. Instead of one voter rating one candidate a 7, say, instead what you have is 100 voters of whom 70 vote yes on the candidate and 30 vote no. Once you have enough voters that that effect is statistically reliable, there's no further need for the added complexity of allowing more scale values.
And as you add scale values, tampering gets even easier. How would we notice it if someone went in and changed a bunch of people's 6 votes to 7s?
What I was unclear about is that our best method for fighting the current system is to convince a significant portion of the electorate to vote for a third party candidate.
Because we all know the system is against us, we are afraid to work together to circumvent it.
We can't replace the system until we use our votes to do so.
A third party is always a spoiler in the current electoral system. We can only fix the problem by using the current system or exploiting it to apply the agenda.
We need main 2-party candidates like Ron Paul and Bernie Sanders (who understood that running as an Independent is mathematically impossible in any meaningful election so switched their party affiliations).
> “It's not psychology but basic probability math and game theory.”
while it’s true that a system set up that way with the given behavioral preconditions likely devolves into those stable solutions, you have the causality backwards. the math is descriptive of a behavioral phenomena, rather than prescribing the outcomes. human behavior seems fixed but it’s highly adaptive. just when you think you’ve figured it out, the system changes on you.
I think Us-Them is much larger than two-party. When you look at countries with multiple parties it doesn't seem their political systems are wildly more efficient.
I think US vs THEM is incomparably bigger than the question of politics. Would 9/11, Vietnam, Iraq, hollocaust, or most wars for that matter have been possible without Us vs them? What about most corruption? What about class systems?
