This has been going on since the 1980s. Facebook may be an accelerant, but it didn't start this fire—not by a long shot.
Its quite weird, because the exact same narrative of unprecedented polarization has been used under Clinton (during the bipartisan neoliberal policy consensus), Bush, Obama, and Trump (with Biden, its at least usually acknowledged as a continuation of that under Trump, not new), with most major voices just seemingly forgetting the unbroken succession of preceding instances of the same narrative, pretending whatever is currently happening came recently, out of the blue without warning.
I think you can justify the claim that there was a real increase in political tribalism resulting from the resolution of the long post-WWII set of political realignments that was particularly evident from about the 1994 midterms and the Contract With America through today. (With some signs as far back as the 1980s as the lines of the new alignment started to become clear and the parties really accelerated movement toward their new polarity, where previously major ideological divides weren't aligned with the major partisan divide, so that ideological factions, to succeed, had to work across party lines.) But that's not as sexy a narrative as “suddenly we woke up in this election cycle with divisiveness that just came out of nowhere”.
Because a lot of people want to believe that the time in which they live is more special and more different than the ones that came before.
The problem is, the internet, the web, and now social media has accelerated this divisiveness to a whole new point. As the GP says, it's an accelerant. Like a small cooking fire can turn nasty with the addition of gas, the acceleration of the culture wars thanks to the winner-take-all outcomes of today mean that everything is getting more heated _faster_.
EDIT: While I know it's faux pas, I am curious where/why the downvotes are coming (from) simply because this seems fairly non-controversial, and also because it started out with a few upvotes first.
I think its pretty obvious to anyone whose knowledge of US history extends earlier than the 1960s that it did not start there (and, also, that the existence of the culture war and partisan polarization, while not unrelated, are quite distinct.)
> The problem is, the internet, the web, and now social media has accelerated this divisiveness to a whole new point
No, its not, as looking at US history anytime outside of a partisan realignment will show. Partisan polarization is a feature of the divide between the major parties in the two-party system aligning with the major ideological divides in the country, which they tend to do in a normal stable political alignment, but not during a period of partisan realignment.
The relatively low level of partisan divisiveness (despite the often quite high level of ideological divisiveness, seen in overlapping things like the Civil Rights Movement, the Anti-War Movement, the youth counterculture/“hippie” movement, etc.) in the (roughly) WWII to 1990s period isn't due to some kind of weird temporary absence of technology needed for partisan division, it is due to the long and overlapping partisan realignments spurred by (mainly) the New Deal Coalition and parties settling out their positions on civil rights. These things meant that on the politically salient ideological issues, the divide between the parties was not aligned with the major cleavages; “liberal Republicans” were farther left on the key ideological issues of the day than “conservative Democrats”, and the opposing ideological factions were present in both parties.
That political realignments had largely settled out by the mid-1990s, with Clinton and the remaining “conservative” Democrats who hadn't defected to the Republicans solidly to the left of what was acceptable for Republicans, and vice versa, which enabled ideological division to translate more directly into partisan division.
A feature? I'm not aware of any document written by the American founders that calls this a "feature" of the system. An emergent property of FPTP perhaps but not a feature. I'd call it a mistake to attribute more to FPTP than its intuitive appeal; the American founders invented FPTP off-the-cuff.
> The relatively low level of partisan divisiveness (despite the often quite high level of ideological divisiveness, seen in overlapping things like the Civil Rights Movement, the Anti-War Movement, the youth counterculture/“hippie” movement, etc.) in the (roughly) WWII to 1990s period isn't due to some kind of weird temporary absence of technology needed for partisan division, it is due to the long and overlapping partisan realignments spurred by (mainly) the New Deal Coalition and parties settling out their positions on civil rights. These things meant that on the politically salient ideological issues, the divide between the parties was not aligned with the major cleavages; “liberal Republicans” were farther left on the key ideological issues of the day than “conservative Democrats”, and the opposing ideological factions were present in both parties.
Right but what _caused_ this political realignment? I mean sure, you can say that the ideologies were extant and during the Civil Rights Movement (and that this divide itself traces itself back to the Reconstruction period and before that into the founding of the US itself) the New Deal Coalition began unraveling and formed the seeds of today's divide, but I submit a large part of what exacerbated that divide was technology. FDR was a popular president and helped cement the New Deal coalition largely because of his use of radio. Likewise Goldwater and early televangelists received a lot of their support from the rise of TV. Social media is just the continuation of this ongoing technological trend.
There's a difference of kind to mass broadcast on a platform one incidentally scrolls (and thus receives incidental exposure from) versus, say, chain emails. The latter have a lot lower impact and require way more activation energy to push onward than a one-click Share.