Counterpossibles in science: an experimental study

Abstract

A counterpossible is a counterfactual whose antecedent is impossible. The vacuity thesis says all counterpossibles are true solely because their antecedents are impossible. Recently, some have rejected the vacuity thesis by citing purported non-vacuous counterpossibles in science. One limitation of this work, however, is that it is not grounded in experimental data. Do scientists actually reason non-vacuously about counterpossibles? If so, what is their basis for doing so? We presented biologists ( N = 86) with two counterfactual formulations of a well-known model in biology, the antecedents of which contain what many philosophers would characterize as a metaphysical impossibility. Participants consistently judged one counterfactual to be true, the other to be false, and they explained that they formed these judgments based on what they perceived to be the mathematical relationship between the antecedent and consequent. Moreover, we found no relationship between participants’ judgments about the (im)possibility of the antecedent and whether they judged a counterfactual to be true or false. These are the first experimental results on counterpossibles in science with which we are familiar. We present a modal semantics that can capture these judgments, and we deal with a host of potential objections that a defender of the vacuity thesis might make.

How people think about the truth of hypothetical impossibilities

“…A key function of such an impossible conditional may be to rule out its hypothetical outcome, to emphasise it as untrue. The results here imply that people can find them useful, not only in the domain of science (e.g., Jenny, 2018;McLoone, 2020;McLoone et al, 2023;Tan, 2019), but also in everyday life.…”

The qualitative study of scientific imagination.

“…That would be surprising, as the general prevalence of aphantasia in humans is currently thought to be only 2%–3% (Faw, 2009; Zeman et al, 2020). However, recent work employing quantitative methods suggests that 16% (of a small sample of biologists) described themselves as fully aphantasic and 35% as aphantasic to some degree (McLoone et al, 2023). This raises the general question of the prevalence of aphantasia among scientists and across scientific disciplines.…”