Henning Kirschbaum
Johannes Gutenberg-Universität Mainz
In this paper, I will argue that we use a heuristic to ascribe abilities, the obstacle heuristic. I show that once our use of this heuristic is understood, seemingly compelling arguments against free will can be rejected. The paper has two parts.
In the first part, I will develop the obstacle heuristic, drawing on an outline by Lewis (2023). According to the heuristic, for a basic action φ, one is able to φ just in case there is no obstacle, i.e. just in case one might φ. ‘Might’ can be read to express a restricted possibility (Williamson 2020). The degree of restriction depends on the kind of ability to be ascribed. For a generated action χ, one is able to χ just in case there is a basic action one is able to perform such that one would χ by performing the basic action. However, to be efficiently applicable, we normally use the obstacle heuristic in tandem with another heuristic, the persistence heuristic. According to this second heuristic, small changes do not matter (Williamson 2024).
In the second part, I discuss the obstacle heuristic’s implications for the problem of free will. On the one hand, we firmly judge to have free will understood as the ability in the relevant sense to act otherwise. On the other hand, we firmly judge both the consequence and the Mind argument to sound according to which free will is incompatible both with determinism and indeterminism and thus impossible (van Inwagen 1983; 2017). Hence, some of our judgments must be false. As they concern abilities, we judge the crucial premises of both the consequence and Mind argument to be true based on the obstacle heuristic. However, both theses are only true according to the obstacle heuristic if the persistence heuristic is inhibited such that we also consider small changes. But normally we only use the obstacle heuristic in conjunction with the persistence heuristic. Our judgement that we have free will, on the other hand, is based on the obstacle heuristic used with the persistence heuristic. Given this, the most charitable interpretation of our thinking about free will is that the incompatibility arguments are unsound and that we have free will.
Literature
Inwagen, Peter van. 1983. An Essay on Free Will. Oxford: Clarendon Press.
———. 2017. Thinking about Free Will. Cambridge University Press. https://doi.org/10.1017/9781316711101.
Lewis, David. 2023. ‘Nihil Obstat: An Analysis of Ability (2001)’. In Philosophical Manuscripts, by David Lewis, edited by Frederique Janssen-Lauret and Fraser Macbride, 214–17. Oxford: Oxford University Press. https://doi.org/10.1093/oso/9780192847393.003.0043.
Williamson, Timothy. 2020. Suppose and Tell: The Semantics and Heuristics of Conditionals. Oxford: Oxford University Press. https://doi.org/10.1093/oso/9780198860662.001.0001.
———. 2024. Overfitting and Heuristics in Philosophy. Oxford: Oxford University Press. https://doi.org/10.1093/oso/9780197779217.001.0001.
Chair: Satbhav Voleti
Time: 03 September, 18:10-18:40
Location: HS E.002
SOPhiA 2026 