The only points when "sanity prevailed" were when there was a clear Other to rally against and fight a war. The hyperpartisanship we're seeing is actually normal for the US.

The US was broken in the 1800s. It was broken in the 1820s-1840s with the fight over slavery. It was broken in the 1860s, and we had to fight a civil war to restore any sort of santy. It was broken in the 1880s after Restoration was rolled back. It was broken in 1900 with the rise of the Klan again. 1915 was WWI, in 1920 we were back to being broken. 1930s we were broken by depression and the fight against fascism, 1940s we had WW2. 1950s we had Korea, 1960s we were broken, 1970s we were broken, and that begun the decline of any sense of civility in the congress.

1980s we were completely broken, 1990s we were completely broken, 2000s we were completely broken, 2010s we were completely broken...

The lack of justice for Nixon broke any sense of normality left in the nation. And the Republicans nevertheless played off the idea that Nixon was somehow crucifed, and elected Reagan, then went on a witch-hunt against Clinton. Then they elected a historically bad president in Bush, started the longest wars in US history, and when people complained they crucified Obama in response. And then they elected the loudest finger-in-the-eye they could find in response.

The US has been somewhat broken for literally its entire existence but it has been actively unable to transact its internal business for about half of that... about half of that being in the last 50 years.

I think there are two big issues there.

The first is softball and obvious. Things can work on a small scale and collapse on a large scale. We started with around 30,000 citizens per congressional district (and thus per representative). And there was a strong urging to push it lower by some. This number was envisioned as remaining as a constant, for if you dilute the power and "connection" of the average voter too much, you risk exposing yourself to politicians too far detached from their constituency which can breed tyranny, corruption, and so on. And indeed 30,000 is already pretty far up there. Today we have more than 700,000 citizens per congressional district.

The second is a more contentious issue, but perhaps even more relevant. Today we've become an increasingly divided and polarized society where nuance is increasingly a lost art. Democracy does not work in such situations. Iraq is an extreme example. Iraq is fundamentally broken up into three major groups - Shiite, Sunni, and Kurds. And these groups tend to be extremely intolerant of one another with members of each group generally adopting wholesale all views of their own group and only their own group. It just turns into a tyranny of the majority.

Somehow the United States has started trending towards this exact behavior. This wasn't always the case. While we may have had vice president engage in a duel to the death with a secretary of the treasury, these were personal conflicts. Today people are engaging more in group conflicts. Democracy works when people are willing to work together, not when they view politics as a team sport where the idea is for your side to "win" and the other side to "lose."

Well, Iraq never developed the traditions or culture or whatever the preconditions for a democracy are. One was imposed on them by a neither competent nor determined foreign occupation force.

The US has had that precondition for centuries, so if we were to lose it, it would be a very different case fro Iraq, who never had it.

I think the factor behind increased polarisation in the US and across the democratic world probably is this thing right here. The internet! People are now increasingly getting their news and information, and thereby their world view from "social media", not the traditional mass media of the last 2-3 centuries.

It's a huge sea change, and we're only seeing the beginning of it. So far it't looking kinda scary, but things will keep changing quickly, and I think we'll sort things out. We better :)