Who are the real extremists?

[Tartarus Sauce]

A lot of things to unpack here in this thread.

First of all, yes, much more change has occurred ideologically within the Democratic party than the Republican party over the past two decades. Democrats have within the past two years become a majority self-identifying liberal party for what is likely the first time in its history. Compare this to the nineties, where conservatives and liberals composed a roughly equal share of Democrats while moderates made up the plurality.



That's a huge shift, and there has definitely been a noticeable change from the past in terms of the type of talking points that pervade within Democratic circles since there's far less pushback from a conservative segment within the party and far more reception to ideas that would have previously been suppressed or downplayed. That's not a judgement on the changes that have occurred (I'm personally in favor of most of them as a liberal myself), just a statement of fact, a fact captured by the first graph in the tweet.

Compare this to the Republican party, which was already a majority conservative party by the early 90s and have only become more conservative since then. The shifts aren't anywhere near as significant as what we've seen in the Democratic Party.



So yes, clearly the ideological shift has been more dramatic among Democrats over the past two decades than among Republicans, it's not even close in regards to degree. That much is captured within the first graph shared within the twitter post. That being said, Crumpets pointed out the flaw with using this fact to assert that Democrats are more extreme: it doesn't actually take into context the broader picture of where Democrats and Republicans lie on the political spectrum in general.

A note must first be made that the next two graphs in the tweet deal with data regarding the ideology of congressional representatives rather than voters, which is what was being measured in the first graph. Additionally, the data in the first graph is taken from Pew Research Center's political typology model, which is not the same parameter that was used to calculate the political ideology of congressional members, the DW-Nominate. So not only do the three graphs measure the ideology of different segments of the political system, they measure ideology differently as well.

As for those two graphs regarding congressional ideology, they make the exact opposite point the tweeter was trying to make. In contradiction to the assertion of the tweeter that Republicans have "barely moved", the third graph in particular demonstrates the infamous "asymmetric polarization," whereby the congressional Republican median has shifted much further to the right since 1970 while the Democratic median in Congress has only budged slightly leftward. The median is what actually conveys where the congressional party ideology is in that graph, not the 10th percentile wing. As for the medians, the Republicans are more rightward leaning than the Democrats are leftward, with Republicans in 2018 scoring a 0.5 on the DW-Nominate and Democrats scoring a -0.4. The 10th percentile wing is so much larger in the 2018 line for Democrats because the 10th percentile wing is now broader and more left leaning than it was before, but it's still the leftmost 10th percentile of the Democratic congressional caucus, not its core. The most conservative 10th percentile of the Republican caucus is similarly far out from the center, but is restricted to a much narrower range. The 10th percentile of the Democratic caucus starts only slightly more leftward of center than the median Republican caucus member is rightward of center.

What's actually happening is that the conservative wing of the Democratic party has atrophied and been replaced by an invigorated left wing. The Gallup survey on political identification over time within the Democratic party showed as much, and you can observe this as well in the second graph. Note how narrow the ideological scope is for Republican primary winners over time, especially post-2010. The distribution curve overwhelmingly favors a narrow band of ideological conservatives, while the Democratic parties distribution curve is much broader in every instance. What's changed is that Democratic primary voters no longer elect members to the right of the political center like they used to and have shifted the entire range of their elected politicians leftward. Yet its clear just from looking at the distribution that Democrats are still a much bigger-tent party that elects a broader ideological scope of candidates than Republicans, who are far more homogenized in their electoral preferences. While the median for Democrats on this graph has probably shifted leftward from where it would have been decades earlier, the median is probably not more leftward for Democrats than it is rightward for Republicans. This graph's data also doesn't match well with the actual trends overtime for the medians in the congressional caucuses, particularly on the Republican side, making me wonder if ideology was being calculated by something other than the DW-Nominate.

Now to bring things back to the first graph. This is the only graph that actually strictly promotes the idea the tweeter wanted to: that the left has ideologically changed much more quickly than the right. But what about OP's use of the data as an argument that Democrats are extremists? Pew Research Center's political typology survey doesn't measure political extremism, it measures how consistently liberal or conservative somebody is in response to a set of ten values-based questions. Unless you're going to make the argument that being a liberal is itself a form of extremism, the graph doesn't prove anything other than that Democrats are now more consistently liberal on the ten questions asked on the survey by the Pew Research Center. And if you're going to consider ideological homogenization as a measure of extremism, keep in mind that Republicans demonstrate far more homogeneity on self-identified ideology, as shown by the Gallup surveys I posted, and also elect a much narrower ideological range of politicians than Democrats. Additionally, outside of of the political typology model employed by Pew, Republicans have demonstrated to be much more ideologically homogenized on broader measures of general conservative orientations than Democrats are around liberal values.

TL;DR

The tweeter's and OP's arguments are severely flawed and the graphs presented do not effectively present the case that Democrats are becoming extreme ideologues.

1. The first graph does demonstrate a dramatic shift in Democratic tendencies to answer consistently liberal on Pew's political typology survey. This isn't that surprising considering the fact that liberals are becoming a more prominent part of the Democratic coalition. However, the survey doesn't demonstrate that Democrats are becoming more extreme because it doesn't measure ideological extremism, it measures ideological consistency. Other studies outside of those conducted by Pew also show that Republicans are very motivated by conservatism as a general driving principle for their political activism in a way that liberalism has failed to match among Democrats as a whole. This is starting to change, but Democrats have a long ways to catch up if they are to become as equally motivated by ideology as Republicans.

2. The second graph is a bit weird and doesn't gel well with the data in the third graph, but nonetheless does demonstrate a shift among Democrats towards more liberal candidates in general in primaries. However, it also demonstrates that Democrats are a much bigger tent party than Republicans with a greater diversity of ideological representation (backed up by self-identification patterns in Gallup surveys, even as liberalism increases, more Democrats still identify as moderates or conservatives than do Republicans as moderates or liberals) while Republicans elect a much narrower ideological scope of candidates. This contradicts the implications of the narrative pushed by the first graph.

3. The third graph completely undermines the assertion tweeter and OP wanted to make. Median Republican congressional ideology has shifted dramatically rightward over the decades while the median Democratic congressional ideology has shifted only modestly leftward. Additionally, the current Republican median in Congress is further away from the political center than the Democratic median according to the DW-Nominate.