True.
> Even a lot of the domestic political polarization and social crackup we see in America today can be traced back to the divisions that be Iraq War created.
Less true,IMO. There's a line through divisions over post-9/11 policy, but it doesn't really start there and there's not much specially about it; its pretty consistent with the trend of crystallization of the polar positions after the end of the long realignment period of the overlapping New Deal and Civil Rights partisan realignements in the early-mid-1990s.
If you look right around the gearing up for the Iraq War it may look like a big acceleration of divisions, but that's mostly unleashing what was deferred in the rally-around-the-flag effect in the immediate aftermath of 9/11.
By the time the post-war occupation had started to slog into a quagmire (the run-up to the 2004 presidential election), we had basically witnessed the dawn of our modern age.
No, it wasn't; Fox had done that before, and and MSNBC, to the extent it eventually did, didn't until much later (9/11 occurred during, and didn't end, the period where MSNBC and CNN were kinda trying to compete with Fox in the same ideological targeting even though CNN was consistently painted as the Left network by the Right, and MSNBC didn't acquire a fairly consistent “left”, or at least Democratic, editorial position until into Bush’s second term, as a gradual evolution from a mix of different editorial positions.
> and when political discourse on the internet started to really sour.
As someone who was online pretty continuously since when “political discourse on the internet” met Usenet, the idea that it started to sour only after 9/11 is silly. More people started interacting online around that time, but that was more driven by easy blogging platforms becoming available and internet access becoming more ubiquitous than 9/11 or any connected political actions.
The polarization started during the Civil Rights era of the 1960s. Or rather, the parties started sorting themselves on various issues after that point.
Ezra Klein has a good US-perspective/history in his recent book:
* https://en.wikipedia.org/wiki/Why_We%27re_Polarized
Humans were always polarized. The political parties in the US just didn't bother acting on that fact until the national Democrats turned their backs on the Dixiecrats, and the GOP then started their Southern Strategy.
No, the polarization on racial issues started before the founding. It came to a head numerous times, the Civil Rights Era of the 1950s-1960s being, while one of the more recent notable times, not anywhwere close to the most significant. (I mean, its quite obviously absolutely dwarfed by the time racial issues came to a head in the 1850s-1860s.)
> Or rather, the parties started sorting themselves on various issues after that point.
No, they’d been doing that since the Democratic New Deal Coalition of the 1930s broke the old partiaan alignment, what changed in the 1960s is that, unlike the similar split in the Democratic Party in the 1940s that broke off the Dixiecrats over racial issues, the Republicans sought to exploit the Democratic divisions and welcome disaffected racists via the Southern Strategy.
The current partisan polarization is largely because, since the long political realignment largely settled out in the 1990s, we’ve had the longest period in a century where the main ideological divides are aligned with the partisan divide between the two major parties.
Even a lot of the domestic political polarization and social crackup we see in America today can be traced back to the divisions that be Iraq War created.