Fans of Thomas Sowell might remember the first question he applies to “self-righteous nonsense that abounds on so many subjects”: Compared to what?

What he means is that people who complain about the negative impact of some practice or policy rarely describe what would happen in the absence of that practice or policy. They imply conditions would be better, but they rarely put that assertion to the test.

When they fail to offer a counterfactual, their interlocutors ought to reply: Compared to what?

That’s why it’s nice to read a recent academic journal article that attempts to show how gerrymandering actually affects representation in the U.S. House of Representatives. A common argument holds that Republicans control the U.S. House thanks to gerrymandering.

Jowei Chen of the University of Michigan and David Cottrell of Dartmouth College set out to test that notion. The results appear in a 2016 edition of the journal Electoral Studies.

Since we only observe Congressional elections where the districts have potentially been gerrymandered, we lack a non-gerrymandered counterfactual that would allow us to isolate its true effect. To overcome this challenge, we conduct computer simulations of the districting process to redraw the boundaries of Congressional districts without partisan intent. By estimating the outcomes of these non-gerrymandered districts, we are able to establish the non-gerrymandered counterfactual against which the actual outcomes can be compared. The analysis reveals that while Republican and Democratic gerrymandering affects the partisan outcomes of Congressional elections in some states, the net effect across the states is modest, creating no more than one new Republican seat in Congress. Therefore, the partisan composition of Congress can mostly be explained by non-partisan districting, suggesting that much of the electoral bias in Congressional elections is caused by factors other than partisan intent in the districting process.

That’s from the abstract. Deeper within the report, we find the following:

This suggests that if districts were drawn randomly with respect to partisanship and race, Republicans would only expect to lose a single seat in Congress to the Democrats. Therefore, although we identify the partisan gains from gerrymandering in a number of states, these gains tend to be small and generally cancel out in the aggregate.

Such a result is meaningful because it contradicts a common perception that major partisan gains in seat share are made in the House of Representatives through gerrymandering. Instead, the evidence suggests that the partisan makeup of the House would be almost no different if gerrymandering – both partisan and racial – were altogether eliminated. Although some state delegations would see significant change, the aggregate advantage received by a particular party in Congress would be almost zero.

So while redistricting reform is a good idea, no one should expect that the end of gerrymandering would mark the end of Republican control of Congress. Hmmm. That sounds familiar.