There's No Such Thing as "Following the Science"

Ezra Klein quotes a Harvard epidemiologist's criticism of the FDA for blocking rapid at-home Covid tests: "They are inadvertently killing people by not following the science."

I agree with the spirit of the criticism (and was heartened to read that Biden’s surgeon general nominee agrees that the FDA has been "too conservative"), but it's worth clarifying that the FDA's failure here is fundamentally ethical, not scientific.

It's a popular rhetorical move, to present one's preferred policies as being backed by the authority of science.  It immediately puts one's critics on the back foot: who are they to question science, after all?  But it's also misleading.  Science doesn't recommend policies for us to follow, for the simple reason that science merely tells us what is the case, and cannot by itself answer normative questions about what ought to be done.

Whether we realize it or not, we use normative bridging principles to cross the is/ought gap.  If some such principle is implicitly presupposed in a context, it might then seem as though the scientific claim alone suffices to yield a policy recommendation.  Opponents of the policy may then try to undermine our scientific knowledge in order to muddy the waters (cf. climate and covid "skeptics").  Perhaps such silliness could be decried as a failure to "follow the science". But such a framing risks reinforcing the mistaken impression that the science alone determines what should be done.  It's often worth making explicit the underlying normative bridging principles, not least because these are often debatable and worthy of critical scrutiny.

Difficult policy decisions tend to involve trade-offs, whether between different people's interests, different kinds of values, or different levels of risk.  This is what makes them difficult.  Accurate scientific data is crucial for getting clear on what the prospects for various policy options look like: the range of possible outcomes and their probabilities.  But that still leaves open the crucial normative work of evaluating those prospects, or making the difficult trade-offs.

Of course, most of the time when people say "follow the science," what they really mean is, "follow the scientists."  But scientists have no expertise in evaluating trade-offs.  They aren't experts in ethical or rational decision-making.  Again, their expertise merely concerns the descriptive facts, providing the essential inputs to rational decision-making, but not what to do with those inputs.

If you blindly defer to doctors and scientists, the resulting policies will be distorted by whatever implicit normative bridging principles they happen to unreflectively hold.  These are likely to be unduly conservative (since most people suffer from a wide range of conservative biases).  They may oppose challenge trials and other utilitarian policies as "too risky" for the participants, not because they have a more accurate conception of what the risks actually are, but because they lack moral understanding of when risks of that magnitude can be justified.

Don't get me wrong: I like science, and I like scientists.  We should defer to them on empirical questions: what the facts are, and what the risks are.  But they do not have the expertise to evaluate either those facts, or those risks.  If you want to trust and follow the experts, you need more than just doctors and scientists at the table.