Degrees of riskiness, falsifiability, and truthlikeness. A neo-Popperian account applicable to probabilistic theories. Leander Vignero Sylvia Wenmackers
[email protected] [email protected] KU Leuven, Institute of Philosophy, Centre for Logic and Philosophy of Science, Kardinaal Mercierplein 2 { bus 3200, 3000 Leuven, Belgium. July 7, 2021 (Forthcoming in Synthese.) Abstract In this paper, we take a fresh look at three Popperian concepts: riskiness, falsifiability, and truthlikeness (or verisimilitude) of scien- tific hypotheses or theories. First, we make explicit the dimensions that underlie the notion of riskiness. Secondly, we examine if and how degrees of falsifiability can be defined, and how they are related to var- ious dimensions of the concept of riskiness as well as the experimental context. Thirdly, we consider the relation of riskiness to (expected degrees of) truthlikeness. Throughout, we pay special attention to probabilistic theories and we offer a tentative, quantitative account of verisimilitude for probabilistic theories. \Modern logic, as I hope is now evident, has the effect of enlarging our abstract imagination, and providing an infinite number of possible hypotheses to be applied in the analysis of any complex fact." { Russell (1914, p. 58). A theory is falsifiable if it allows us to deduce predictions that can be compared to evidence, which according to our background knowledge could arXiv:2107.03772v1 [physics.hist-ph] 8 Jul 2021 show the prediction | and hence the theory | to be false. In his defense of falsifiability as a demarcation criterion, Popper has stressed the importance of bold, risky claims that can be tested, for they allow science to make progress.