In quantum mechanics, the wavefunction predicts probabilities of possible measurement outcomes, but not which individual outcome is realised in each run of an experiment. This suggests that it describes an ensemble of states with different values of a hidden variable. Here, we analyse this idea with reference to currently known theorems and experiments. We argue that the ψ-ontic/epistemic distinction fails to properly identify ensemble interpretations and propose a more useful definition. We then show that all local ψ-ensemble interpretations which reproduce (...) quantum mechanics violate Statistical Independence. Theories with this property are commonly referred to as superdeterministic or retrocausal. Finally, we explain how this interpretation helps make sense of some otherwise puzzling phenomena in quantum mechanics, such as the delayed choice experiment, the Elitzur-Vaidman bomb detector, and the Extended Wigner's Friends Scenario. (shrink)

In discussion of the interpretation of quantum mechanics the terms ‘ontic’ and ‘epistemic’ are often used in the sense of pertaining to what exists, and pertaining to cognition or knowledge respectively. The terms are also often associated with the formal definitions given by Harrigan and Spekkens for the wavefunction in quantum mechanics to be ψ-ontic or ψ-epistemic in the context of the ontological models framework. The formal definitions are contradictories, so that the wavefunction can be either ψ-epistemic or ψ-ontic but (...) not both. However, we argue, nothing about the informal ideas of epistemic and ontic interpretations rules out wavefunctions representing both reality and knowledge. The implications of the Pusey–Barrett–Rudolph theorem and many other issues may be rethought in the light of our analysis. (shrink)

Quantum Counterfactual Communication is the recently-proposed idea of using quantum physics to send messages between two parties, without any matter/energy transfer associated with the bits sent. While this has excited massive interest, both for potential ‘unhackable’ communication, and insight into the foundations of quantum mechanics, it has been asked whether this process is essentially quantum, or could be performed classically. We examine counterfactual communication, both classical and quantum, and show that the protocols proposed so far for sending signals that don’t (...) involve matter/energy transfer associated with the bits sent must be quantum, insofar as they require wave-particle duality. (shrink)

The aim of this paper is to bring an end to the interpretative dispute on Descartes’s cog­ito: is the cogito known by intuition or by inference? There have been several studies based on both analytical and historical approaches to the dispute, and it seems that we have exhausted all interpretations. Nevertheless, I wish to revisit this dispute, as it ap­pears that the previous studies have overlooked Descartes’s use of words and phrases, which is the most significant for understanding his various (...) discourses on the cogito con­sistently. In this paper, I focus on the terms which Descartes uses to indicate the varied status of the cogito, such as ‘haec cognitio, ego cogito, ergo sum’, ‘hanc propositionem, ego cogito, ergo sum’, ‘hanc conclusionem: cogito, ergo sum’, and so on; Descartes changes carefully the terms in each of the cogito arguments. By focusing on these terms, I try to interpret Descartes’s explanations consistently. (shrink)