Spacetime emergence in quantum gravity: functionalism and the hard problem

Abstract

Spacetime functionalism is the view that spacetime is a functional structure implemented by a more fundamental ontology. Lam and Wüthrich have recently argued that spacetime functionalism helps to solve the epistemological problem of empirical coherence in quantum gravity and suggested that it also (dis)solves the hard problem of spacetime, namely the problem of offering a picture consistent with the emergence of spacetime from a non-spatio-temporal structure. First, I will deny that spacetime functionalism solves the hard problem by showing that it comes in various species, each entailing a different attitude towards, or answer to, the hard problem. Second, I will argue that the existence of an explanatory gap, which grounds the hard problem, has not been correctly taken into account in the literature.

On the empirical coherence and the spatiotemporal gap problem in quantum gravity: and why functionalism does not (have to) help

“…The spatiotemporal gap problem is a specific conceptual gap problem between a putatively non-spatiotemporal theory and a derivative spatiotemporal theory, first and foremost set up by Le Bihan (2018a, b) and Le Bihan and Linnemann (2018), and further illustrated in Le Bihan (2019). To be clear: surely, intertheory relations generically involve conceptual gaps.…”

“…Le Bihan (2019) makes an analogy to the qualia problem of consciousness: The spatiotemporal gap problem refers to an explanatory gap between non-spatiotemporal and spatiotemporal structures similar to the explanatory gap between physical states and the supposedly qualitative marks of mental states called qualia (such as what it is like to experience 'redness'). In reference to a well-known nomenclature by Chalmers (2011) who calls the issue of explaining qualia from physical states the hard problem of consciousness, Le Bihan then dubs the problem of bridging the conceptual gap between the non-spatiotemporal and the spatiotemporal the hard problem of spacetime emergence.…”

“…Before we consider whether functionalism would solve the spatiotemporal gap problem, let us remind ourselves that functionalism cannot straightforwardly address the spatiotemporal gap problem of naturalising qualia in the philosophy of mind. As Le Bihan (2019) acknowledges: Functionalism, in the philosophy of mind, aims at solving the mind-body problem by functionalising mental states, namely identifying them with functional roles realised by physical states. Functionalism aims at explaining the (or some) specific marks of the mental with respect to physical entities, namely intentionality and phenomenal consciousness.…”

Humeanism in light of quantum gravity

“…We thus argue that one can attack the problem of reconciling entanglement and Humeanism not by modifying either one or the other, but instead by looking at some tantalising approaches and conjectures regarding the extension of QM to the realm of gravity and spacetime. Studying the interaction of QG with metaphysics is a practice more and more common in the literature, as witnessed by Le Bihan (2019), Matarese (2019), Wüthrich (2019) and Jaksland (2020). This approach holds much promise for the interaction between the edge of physical and metaphysical research.…”

Humeanism in Light of Quantum Gravity

“…We thus argue that one can attack the problem of reconciling entanglement and Humeanism not by modifying either one or the other, but instead by looking at some tantalising approaches and conjectures regarding the extension of QM to the realm of gravity and spacetime. Studying the interaction of QG with metaphysics is a practice more and more common in the literature, as witnessed by Le Bihan (2019); Matarese (2019); Wüthrich (2019); Jaksland (2020). This approach holds much promise for the interaction between the edge of physical and metaphysical research.…”