AAP 2026 CONFERENCE

Richard Jeffrey (1956) famously articulated an internal critique to the argument from inductive risk (AIR) and offered an alternative picture of scientific advice, which we call “the Bayesian picture of scientific advice” (BPSA) with two essential commitments: scientists should only communicate their subjective probabilities (vs. outright beliefs) in hypotheses and doing so upholds a political division of labour (i.e., scientists bring the epistemic input; policy-makers bring the evaluative judgments).

We argue that communicating credences doesn’t deliver the division of labour—the idea that such a prize is secured in the Bayesian picture is an artifact of the idealizations behind the debate around the AIR. Basically: scientists’ role in policy advice goes well beyond reporting credences (or outright beliefs for that matter) for a hypotheses previously specified by policy makers. Scientists are necessarily involved in the framing of policy (decision) problems, i.e., in the curation of the policy actions, the states-of-nature, and outcomes that are worth considering. (They are even needed to come up with utility numbers!) This is easy to see when looking at well-studied cases of scientific advice such as large-scale environmental assessments—we focus on the IPCC reports in the talk—but the point generalizes.