And this, my children, is why we do not say things like “I believe in science”. I mean, don’t get me wrong, science definitely exists—I’ve seen it. But not everything that calls itself science is science, and even good science sometimes gets wrong results. –Megan McArdle

Should we “trust science” or “believe in science”?

I think this is a fuzzy idea that we would do well to make clear and precise. What does it mean to “trust science?”

Does it mean “trust scientists”? Which scientists? They disagree, often vehemently. Which statements of theirs? Surely not all of them; scientists do not speak ex cathedra for “Science.”

Does it mean “trust scientific institutions”? Again, which ones?

Does it mean “trust scientific papers”? Any one paper can be wrong in its conclusions or even its methods. The study itself could have been mistaken, or the writeup might not reflect the study.

And it certainly can’t mean “trust science news,” which is notoriously inaccurate.

More charitably, it could mean “trust the scientific process,” if that is properly understood to mean not some rigid Scientific Method but a rational process of observation, measurement, evidence, logic, debate, and iterative revision of concepts and theories. Even in that case, though, what we should trust is not the particular output of the scientific process at any given time. It can make wrong turns. Instead, we should trust that it will find the truth eventually, and that it is our best and only method for doing so.

The motto of science is not “trust us.” (!) The true motto of science is the opposite. It is that of the Royal Society: nullius in verba, or roughly: “take no one’s word.”

There is no capital-S Science—a new authority to substitute for God or King. There is only science, which is nothing more or less than the human faculty of reason exercised deliberately, systematically, methodically, meticulously to discover general knowledge about the world.

So when someone laments a lack of “trust” in science today, what do they mean? Do they mean placing religion over science, faith over reason? Do they mean the growing distrust of elites and institutions, a sort of folksy populism that dismisses education and expertise in general? Or do they mean “you have to follow my favored politician / political program, because Science”? (That’s the one to watch out for. Physics, chemistry and biology can point out problems, but we need history, economics and philosophy to solve them.)

Anyway, here’s to science—the system that asks you not to trust, but to think.

Adapted from a 2019 Twitter thread.