Functionalising the wavefunction

Functionalism, Reductionism, and Levels of Reality

“…In the philosophy of mind (cf. Kim 1998), the reduction of folk psychology to physiology is used to functionally reduce mental states to brain states; in Wüthrich (2018, 2020), theoretical reduction of general relativity to quantum gravity backs the functional reduction of space-time to nonspatiotemporal structures; in Albert (2015) and Lorenzetti (2022), theoretical reduction between laws of quantum mechanics and classical laws is used to argue for the functional reduction of three-dimensional entities to quantum wave functions; finally, a realist stance is supported by Butterfield and Gomes (2020b) in the recovery of time from geometrodynamics. 8 We can thus notice that, given that the Lewisian model delivers (deduced) bridge laws in the form of identities between the theoretical terms, if we give an ontological interpretation of those terms, then it follows that functional reduction entails (type) identity relations between the elements of the two ontologies.…”

“…I present here an example of functional reduction in physics, concerning classical and quantum systems, drawing on Lorenzetti (2022). This is a simple instance of functional reduction, but it is nevertheless a realistic case study, and it allows us to see more closely how functional reductionism works in the Lewisian model and how it leads to identity relations.…”

“…The reductionist aspect of functional reductionism then follows from how this This leveled and asymmetrical conception of reality can indeed be found in those situations in which functional reductionism is applied in practice. For instance, if we functionally reduce classical systems to quantum systems (as we did in our simple earlier example and as is done by Albert [2013Albert [ , 2015 and Lorenzetti [2022]), or space-time to nonspatiotemporal structures (cf. Lam and Wüthrich 2018), the assumption would be that the former kind of entity is functionally reduced to the latter and not the other way round.…”

“…See also Butterfield (2011aButterfield ( , 2011b and Dizadji-Bahmani et al (2010). 4 See Lewis (1970), Kim (2005), Morris (2020), Esfeld and Sachse (2007), Wüthrich (2018, 2020), Gomes (2020b, 2020a), Robertson (2020), Lorenzetti (2022).…”

“…Then, there is functional reductionism. Versions of this view have been defended in the philosophy of science by several authors, especially in recent years (see Lewis 1970; Kim 2005; Morris 2009; Esfeld and Sachse 2007; Lam and Wüthrich 2018, 2020; Butterfield and Gomes 2020a, 2020b; Robertson 2022; Lorenzetti 2022). 2 The target of this article is, in particular, the Lewisian formulation of functional reductionism, which is the most developed version of the account to date.…”