Conference Agenda

A particular theoretical development of quantum mechanics, called the process matrix formalism (PMF), features what is called causal nonseparability. The PMF appeals to the notion of quantum process, which is a generalisation of the concept of quantum state allowing to represent quantum-like correlations between quantum events over multiple parties without specifying a priori their spatiotemporal locations. Crucially, since the PMF makes no assumption about the global causal structure between quantum events, it allows for the existence of causally nonseparable quantum processes having an indefinite causal order (ICO).

As a first step, this work aims at investigating the philosophical implications of causal nonseparability, especially for the notion of spatiotemporal relations. We show that, depending on the interpretative framework, causal nonseparability suggests some kind of indeterminacy of spatiotemporal relations. Importantly, this result hinges on the particular physical implementation of ICOs.

As a second step, we discuss possible implications on the laws of nature, and ask whether these results could help illuminate the status of spacetime in approaches to quantum gravity in which spacetime is emergent, rather than fundamental

Cases in which many agents contribute to an outcome, such as individual agents contributing to climate change, pose puzzles for theories of causation. Tiefensee has recently argued that these cases may be infected with indeterminacy, since it is sometimes indeterminate whether such actions can make a difference to an effect. This result is consistent with earlier arguments by Bernstein, Sartorio, and Swanson, that causal claims are sometimes indeterminate. In this paper, I develop a theory of causal indeterminacy that can adequately capture both cases. The theory I propose combines Woodward’s interventionist approach to actual causation with the conceptual tools of supervaluationism, which are commonly used to explain semantic vagueness.

The paper first investigates (some) relations between multidimensional properties, graded properties and indeterminate properties. It then proposes different formal models that are able to capture significant aspects of those relations.