Abstract

Scientists and their supporters often portray as exasperatingly irrational all those laypersons who refuse to accede to practical recommendations issued by expert scientists and 'science appliers'. After first considering the latter groups’ standard explanations for such non-deference, which focus upon irrationalities besetting the laity, I will propose that a better explanation for at least some of the non-deference is that many laypersons are rationally electing to substitute their own judgments for those urged upon them by the scientific community. Science-based recommendations, as I treat them, have the general form In light of the science on X, if you seek outcome O, you ought to V. Non-deferring laypersons deny the soundness or cogency of the V-supporting argumentation—though they are supposedly not competent to do so, given their gross epistemic inferiority to the scientific authorities who create and endorse the arguments. On account of thus being epistemically irrational, they end up being instrumentally irrational, pursuing courses of action that are poor choices for serving their own interests. The non-deferring laypersons are thought to violate two mandates of rationality: for internal deference to the underlying science as true enough to constitute an unproblematic background for decisionmaking, and for external deference to the practical application of that science to the concrete extra-scientific circumstances in question. I claim that rationality does not require categorical adherence to these mandates. In any given case, non-deference by some laypersons might be warranted by one or more of four distinct rationales. 1. Value-ladenness: The science-based recommendation discernibly includes non-scientific value-choice or value-weighting assumptions. It embodies a certain prioritizing of the plurality of specific values packed within its O parameter, and some laypersons may permissibly substitute their own. 2. Non-scientific-reasoning-ladenness: The science-based recommendation discernibly relies upon reasoning moves that are not distinctive to science, moves whose critical assessment demands no scientific expertise. Error-free reasoning is difficult to attain, and the laypersons may justifiably take themselves to have found weaknesses in the V-supporting argumentation that undermine the case for conformity to the recommendation. 3. Overgeneralization: The science-based recommendation discernibly is not adequately tailored to the specific situation of the laypersons in question. 4. Untrustworthy science: The science-based recommendation discernibly is based upon scientific research that is of doubtful quality. The first three rationales cast doubt upon the External Deference Mandate, questioning not the existence of sound underlying research but the recommendation’s judgments about how this research ought to be applied. The fourth is a challenge to the Internal Deference Mandate.