R.I.G Hughes offers the first detailed and accessible analysis of the Hilbert-space models used in quantum theory and explains why they are so successful.

Noncontextual hidden variables theories, assigning simultaneous values to all quantum mechanical observables, are inconsistent by theorems of Gleason and others. These theorems do not exclude contextual hidden variables theories, in which a complete state assigns values to physical quantities only relative to contexts. However, any contextual theory obeying a certain factorisability conditions implies one of Bell's Inequalities, thereby precluding complete agreement with quantum mechanical predictions. The present paper distinguishes two kinds of contextual theories, ‘algebraic’ and ‘environmental’, and investigates when factorisability (...) is reasonable. Some statements by Fine about the philosophical significance of Bell's Inequalities are then assessed. (shrink)

I. Causal Thesis: Dispositions have a causal basis. II. Distinctness Thesis: Dispositions are distinct from their causal basis. III. Impotence Thesis: Dispositions are not causally active.

Several authors have recently attempted to provide a physicalist analysis of causation by appealing to terms from physics that characterise causal processes. Accounts based on forces, energy/momentum transfer and fundamental interactions have been suggested in the literature. In this paper, I wish to show that the former two are untenable when the effect of enclosed electromagnetic fluxes in quantum theory is considered. Furthermore, I suggest that even in the classical and non-relativistic limits, a theory of fundamental interactions should not be (...) reduced to either a theory of forces or of energy/momentum transfer, but should be understood as a classical account of mutual interactions. Causal links are therefore correctly characterised by generalised potentials. This leads to some speculation regarding the fundamental ontology of interactions and, in particular, the role of the quantum mechanical phase. (shrink)

The concepts in the title refer to properties of physical theories and this paper investigates their nature and relations. The first three concepts, especially gauge invariance and indeterminism, have been widely discussed in connection to spacetime theories and the hole argument. Since the gauge invariance principle is at the crux of the issue, this paper aims at clarifying the nature of gauge invariance. I first explore the following chain of relations: gauge invariance $\Rightarrow $ the conservation laws $\Rightarrow $ the (...) Cauchy problem $\Rightarrow $ indeterminism. Then I discuss gauge invariance in light of our understanding of the above relations and the possibility of spontaneous symmetry breaking. (shrink)

The objective of this paper is to show that, instead of quantum probabilities, wave packets are physically real. First, Cartwright's recent argument for the reality of quantum probabilities is criticized. Then, the notion of ‘physically real’ is precisely defined and the difference between wave functions and quantum probabilities clarified. Being thus prepared, some strong reasons are discussed for considering the wave packet to be physically real. Finding the reasons inconclusive, I explain how the Aharonov—Bohm effect delivers the final punch. I (...) conclude that wave packets are the quantum objects that underlie the indeterministic quantum processes and have the propensity of displaying probabilistic (or indeterministic) behavior. (shrink)