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Updated: Aug 7, 2026

Perspectives on Neuroscience
Published on: July 31, 2007
On indeterminism, chaos, and small number particle systems in the brain
Edwin R Lewis1, Ronald J MacGregor
1Department of Electrical Engineering and Computer Science, University of California, Berkeley, CA 94720-1770, USA. lewis@eecs.berkeley.edu
Abstract:
This paper presents rational, theoretical, and empirical grounds for doubting the principle of determinism in nature and in the brain, and discusses implications of this for free will and the chaos model of the brain. Small number particle systems are practically indeterministic and may be intrinsically indeterministic. Determinism in nature has often been taken to preclude free will. Strict determinism is a concept frequently applied to systems theory, establishing, e.g., the uniqueness of state-space trajectories. In order to consider determinism as a law of nature, however, one must be able to subject it to empirical tests. Presently, one is not able to and whether this can be shown to enable free will or not is not clear. It does remove, at least for the present, determinism itself as a rationale for precluding free will. The work partially supports the chaos model, but weakens the computational computer metaphor of brain function.
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