Physics, Determinism, and the Brain

Abstract: This paper responds to claims that causal closure of the underlying microphysics determines brain outcomes as a matter of principle, even if we cannot hope to ever carry out the needed calculations in practice. Following two papers of mine where I claim firstly that downward causation enables genuine causal powers to occur at higher emergent levels in biology (and hence in the brain) [arXiv:2004.13591], and that secondly causal closure is in reality an interlevel affair involving even social levels [arXiv:2006.00972], Carlo Rovelli has engaged with me in a dialogue where he forcefully restates the reductionist position that microphysics alone determines all, specifically the functioning of the brain. Here I respond to that claim in depth, claiming that if one firstly takes into account the difference between synchronic and diachronic emergence, and secondly takes seriously the well established nature of biology in general and neuroscience in particular, my position is indeed correct.