Ella van Dalen
Radboud University
Do we have free will? This question has plagued philosophers for centuries. In the modern
debate on free will, it is a central problem whether and how free will could exist in a deterministic world. In their 2006[1] and 2009[2] papers, John Conway and Simon Kochen present the Free Will Theorem (FWT), which they hope will provide direction in this debate. They claim that their theorem defends libertarianism.
More specifically, Conway and Kochen aim to prove that if an experimenter can make a choice that is not determined by what has happened in the past, then so can a particle. This freedom is different from free will in philosophy, where free will is often defined as a combination of the conditions of agency and the possibility to do otherwise. This makes it difficult to relate the FWT to the free will debate in philosophy.
Besides Landsman’s argument that the FWT can disprove local miracle compatibilism [3] and Wüthrich’s argument that the FWT does not prove indeterminism [4], the FWT has overall received little attention from philosophers. It has been mostly criticized for its physics claims and lack of novelty in physics[5]. In contrast, I aim to analyse the claims of the FWT from a philosophical perspective, to see to what extent the FWT can be used as an argument in the free will debate.
I then defend the following claims: (1) Conway and Kochen do not prove a meaningful version of free will for particles and (2) their theorem cannot prove indeterminism.
I argue that Conway and Kochen’s use of ‘free will’ is ambiguous and I pose two options for
consistently defining free will in the FWT. I argue that either way the Free Will Theorem does not prove a philosophically meaningful version for particles.
Then I argue that the FWT cannot prove indeterminism, which would be necessary to use the
FWT as an argument for libertarianism, as Conway and Kochen aim to do. In line with Wüthrich [4], I argue that using the FWT as proof for indeterminism is circular reasoning. Because indeterminism is included with the initial assumption that an experimenter can make an undetermined choice.
References
[1] J. H. Conway and S. Kochen, “The Free Will Theorem”, Foundations of Physics 36, 1441–1473 (2006).
[2] J. H. Conway and S. Kochen, “The strong free will theorem”, Notices of the Americal Mathematical Society 56, 226–232 (2009).
[3] K. Landsman, “On the notion of free will in the free will theorem”, Studies in History and
Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 57, 98–103 (2017).
[4] C. Wuthrich, “Can the world be shown to be indeterministic after all?”, in Probabilities in
physics, edited by C. Beisbart and S. Hartmann (Oxford University Press, 2011), pp. 365–389.
[5] S. Goldstein, D. Tausk, R. Tumulka, and N. Zanghi, “What does the free will theorem actually prove?”, Notices of the American Mathematical Society, 1451–1453 (2010).
Chair: Brian Ortmann
Time: 04 September, 10:40-11:10
Location: HS E.002
SOPhiA 2026 