Modal inferences in science: a tale of two epistemologies

Abstract

Recent epistemology of modality has seen a growing trend towards metaphysics-first approaches. Contrastingly, this paper offers a more philosophically modest account of justifying modal claims, focusing on the practices of scientific modal inferences. Two ways of making such inferences are identified and analyzed: actualist-manipulationist modality (AM) and relative modality (RM). In AM, what is observed to be or not to be the case in actuality or under manipulations, allows us to make modal inferences. AM-based inferences are fallible, but the same holds for practically all empirical inquiry. In RM, modal inferences are evaluated relative to what is kept fixed in a system, like a theory or a model. RM-based inferences are more certain but framework-dependent. While elements from both AM and RM can be found in some existing accounts of modality, it is worth highlighting them in their own right and isolating their features for closer scrutiny. This helps to establish their relevant epistemologies that are free from some strong philosophical assumptions often attached to them in the literature. We close by showing how combining these two routes amounts to a view that accounts for a rich variety of modal inferences in science.

Two epistemological challenges regarding hypothetical modeling

“…Instead, these models represent actual targets-say, samples of krypton gas-as having certain modal or counterfactual properties: e.g., "if this actual gas sample's pressure were to be increased, then ceteris paribus its temperature would increase." As Hirvonen et al (2021) have noted, this kind of modal reasoning about actual targets is thoroughly epistemologically unproblematic. This general observation about the modal content of models directed at actual systems applies even in those cases where intervention is impossible (cf.…”

“…It is precisely because the alleged targets of hypothetical models are, as it were, purely hypothetical, that there is a genuine challenge with respect to evaluating these models' surrogate function. Again, even in cases of modeling actual targets where our models might provide modal information, and where we cannot directly intervene on the target of the model, the models' surrogative function can still in principle be evaluated by observation (Hirvonen et al, 2021) or computer simulation (cf. Parker, 2017).…”