According to the Pew Research Center there is evidence that America has become more more polarized since 2016.[1] This is part of a decades long trend.[2] This polarization is happening on both a rational[3] and emotional[4] level. According to some other researchers, political polarization is at its worst since the civil war.[5]
Yep, same thing. Listen to yourself. You expect me to believe a) there's an objective measurement of a well defined term "political polarization" and it has also been happening for more than 100 years or b) US liberals made up some totally arbitrary subjective standard, applied their bias to it, and came out with "Thanks Donald."
A lot to unpack there, so I'll restrict myself to a single remark: your suggestion that the polarization metric used in the last paper was developed post hoc in response to Trump's election doesn't match the publication timeline.
The method[1] used in the last paper has been around since the 80's and has been used to study polarization since at least the 00's. It's a popular method used in many papers; you can even get the raw data and code as an R package if you'd like to hack on it.
[1]: https://www.people-press.org/interactives/political-polariza...
[2]: https://www.people-press.org/2014/06/12/political-polarizati...
[3]: https://www.pewresearch.org/fact-tank/2019/02/05/republicans...
[4]: https://www.people-press.org/2018/11/05/more-now-say-its-str...
[5]: https://news.usc.edu/110124/political-polarization-at-its-wo...