Against the disappearance of spacetime in quantum gravity

TL;DR

This paper challenges the view that spacetime is non-fundamental in quantum gravity, arguing that current proposals lack ontological robustness and that functionalist approaches presuppose spacetime, thus questioning the disappearance thesis.

Contribution

It critically examines the ontological claims about spacetime's non-fundamentality in quantum gravity and highlights the limitations of functionalist reconstructions that presuppose spacetime.

Findings

Current proposals lack ontological robustness.

Functional definitions presuppose spatiotemporal relations.

Spacetime's fundamental status remains plausible.

Abstract

This paper argues against the proposal to draw from current research into a physical theory of quantum gravity the ontological conclusion that spacetime or spatiotemporal relations are not fundamental. As things stand, the status of this proposal is like the one of all the other claims about radical changes in ontology that were made during the development of quantum mechanics and quantum field theory. However, none of these claims held up to scrutiny as a consequence of the physics once the theory was established and a serious discussion about its ontology had begun. Furthermore, the paper argues that if spacetime is to be recovered through a functionalist procedure in a theory that admits no fundamental spacetime, standard functionalism cannot serve as a model: all the known functional definitions are definitions in terms of a causal role for the motion of physical objects and hence presuppose spatiotemporal relations.