Recently, Congress' Select Subcommittee on the Coronavirus Pandemic released its final report. The basic gist is about what you'd expect from a Republican-run committee, in that it trashes a lot of Biden-era policies and state-level responses while praising a number of Trump's decisions. But what's perhaps most striking is how it tackles a variety of scientific topics, including many where there's a large, complicated body of evidence.

Notably, this includes conclusions about the origin of the pandemic, which the report describes as "most likely" emerging from a lab rather than being the product of the zoonotic transfer between an animal species and humans. The latter explanation is favored by many scientists.

The conclusions themselves aren't especially interesting; they're expected from a report with partisan aims. But the method used to reach those conclusions is often striking: The Republican majority engages in a process of systematically changing the standard of evidence needed for it to reach a conclusion. For a conclusion the report's authors favor, they'll happily accept evidence from computer models or arguments from an editorial in the popular press; for conclusions they disfavor, they demand double-blind controlled clinical trials.

This approach, which I'll term "shifting the evidentiary baseline," shows up in many arguments regarding scientific evidence. But it has rarely been employed quite this pervasively. So let's take a look at it in some detail and examine a few of the other approaches the report uses to muddy the waters regarding science. We're likely to see many of them put to use in the near future.

If you've been following the politics of the pandemic response, you can pretty much predict the sorts of conclusions the committee's majority wanted to reach: Masks were useless, the vaccines weren't properly tested for safety, and any restrictions meant to limit the spread of SARS-CoV-2 were ill-informed, etc. At the same time, some efforts pursued during the Trump administration, such as the Operation Warp Speed development of vaccines or the travel restrictions he put in place, are singled out for praise.