The Washington PostDemocracy Dies in Darkness

What Elon Musk’s polarization graph gets wrong

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So the guy who is poised to buy Twitter once again successfully drew attention to Twitter by offering a visual analysis of how American politics has changed in recent years.

This was Elon Musk’s tweet.

The unsubtle point is in keeping with most of Musk’s other non-rocket-related tweets since it was announced that Twitter would accept his buyout bid. The American left had run amok — literally to the left in the illustration — leaving even onetime allies behind. Meanwhile, the right has just been sitting there, watching its opponents head to the fringe.

One can see how this is appealing to Musk, who has leaned into the idea that Twitter is dangerously influenced by extreme left-wing thinking and whose recent engagement on the platform has been to express sympathy toward overt right-wing trolls. But the illustration is simply wrong — not solely in its obvious exaggeration for effect, but in its understanding of how the country has changed over the past decade or two.

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There are a few ways to measure how the country’s politics have shifted. One is to look at who Americans are electing to Congress. On that metric, the picture is actually the opposite of the one Musk presents, as data from VoteView indicate.

On the chart below, the average ideological score (using a metric called DW-NOMINATE) is shown for each party’s caucus in each chamber of Congress. The score runs from minus-1 to plus-1, with lower scores representing more liberal ideologies (as expressed in votes centered on support for government power). The biggest changes have been in the Senate, where, since the start of the 111th Congress in 2009, the Republican caucus has gotten 0.13 points more conservative on average. In each of the other caucuses, the shift has been about 0.04 points toward the poles.

More interesting, really, is the shading, representing the most liberal and most conservative members of each party’s caucus. In 2001, when the graph begins, there was overlap: The most conservative Democrat was more conservative than the most liberal Republican. That’s no longer the case.

There are a lot of valid criticisms of DW-NOMINATE in general that we could examine, but it’s not a great measure of what Musk is talking about anyway. Instead, let’s consider how Americans actually identify their own politics. Luckily, we have a metric for that: evaluations of ideology as measured in the biennial General Social Survey (GSS). The survey asks people to score their identity on a scale from one (extremely liberal) to seven (extremely conservative). In the middle is four, moderate.

Here’s how members of each party (including those who identify themselves as “strong” partisans) have rated their ideology on average since 2002.

What you’ll notice is that Democrats and strong Democrats have, in fact, gotten more liberal — but that Republicans and strong Republicans were far more polarized in the first place.

The change from 2008 to 2012 to 2021 looks like this. Notice that Republicans have, in fact, moved to the right. Notice, too, that Americans overall have moved to the left.

But the most critical point is that Republicans started out much closer to the pole. Musk’s illustration has Republicans equidistant from Democrats at the outset; in reality, they were already much more polarized.

It’s important to recognize, too, that most of the movement among Democrats has been among White Democrats. One reason Joe Biden was successful in the Democratic primary in 2020 was that he was more moderate than his competitors, which helped bolster his support among Black Democrats. What that means is the liberal shift has been larger among White Democrats. If your assessment of the left is mostly informed by your interactions with White Democrats, then you may have an exaggerated sense of the shift. We see some signs of this: Musk and others will certainly point to various cultural examples of how Democrats have moved to the left, but it’s often focused on a specific subset of the Democratic Party. (Just as rejoinders that focus on, say, QAnon focus on a subset of the right.)

Musk’s initial chart centers on changes in ideology, which are hard to measure. (If liberals now hold different positions, were the 2008 liberals still “liberals”?) With our more useful partisan data in hand, though, let’s redesign Musk’s chart.

Accuracy’s never as much fun. Which itself seems like it describes how Musk wants to change Twitter.