Università di Firenze, November, 30, 2021, h. 14.30-15.30 CET

The history of science, and of natural philosophy in general, displays an eternal tension between tendencies pulling in opposite directions. On the one hand, we want to explain as many phenomena as we can (ideally, all phenomena whatsoever) in purely physical terms. This means positing a clear fundamental-level ontology and the laws of nature that characterize its behavior, and then showing how this level is sufficient to capture and explain all (alleged) higher-level phenomena. In one recent incarnation, this project is called ‘flat physicalism’ (Hemmo & Shenker 2020). On the other hand, in the drive to understand and explain innumerable particular phenomena, science has inexorably introduced more and more kinds, types of entities, properties, and structures, without ever showing (and usually without even bothering to try to show) that these ideological novelties are reducible to fundamental physical entities and processes. Despite the elimination of a few suspect kinds from our world-view (such as spirits, deities or humours), scientific progress over the centuries has, in my view, overall taken us further and further from seeing how we might possibly vindicate a flat physicalist ideology.

Arguing for this sweeping claim is beyond what can be attempted in this talk. What I will try to do is question whether flat physicalism can even be defended for fundamental physics itself. My thesis will be that it cannot. Current candidate fundamental theories, all quantum theories of some sort, are themselves resistant to being given a “flat” interpretation; they seem to require higher-level categories, epistemic and/or anthropomorphic in nature, for their very expression. If this is correct, philosophers attracted to flat physicalism and similar programs should feel free to ignore the difficulties of reducing mental, social and teleological categories to the physical, for the time being: the first job that needs doing is to work on making physics itself compatible with physicalism.

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