Using three intuitive notions about causes, including Redhead's robustness condition, I formulate necessary conditions on partial causes. I then demonstrate that we cannot explain the EPR correlations in terms of partial causes unless we abandon the quantum mechanical framework and adopt a nonlocal hidden-variable theory. The argument, unlike its predecessors, does not appeal to relativity theory.

I derive a Gleason-type contradiction from assumptions weaker than those needed to reach a Bell inequality. By establishing the inconsistency between local realism and QM's perfect EPR-type anticorrelations, the proof fills in a gap left open by Bell arguments.

Decoherence results from the dissipative interaction between a quantum system and its environment. As the system and environment become entangled, the reduced density operator describing the system "decoheres" into a mixture (with the interference terms damped out). This formal result prompts some to exclaim that the measurement problem is solved. I will scrutinize this claim by examining how modal and relative-state interpretations can use decoherence. Although decoherence cannot rescue these interpretations from general metaphysical difficulties, decoherence may help these interpretations to (...) pick out a preferred basis. I will explore whether decoherence solves nagging technical problems associated with selecting a preferred basis. (shrink)

Three claims about what makes a theory “physically complete” are (1) Shimony's assertion that a complete theory says “all there is to say” about nature; (2) EPR's requirement that a complete theory describe all “elements of reality”; and (3) Ballentine and Jarrett's claim that a “predictively complete” theory must obey a condition used in Bell deviations. After introducing “statistical completeness” as a partial formalization of (1), we explore the logical and motivational relationships connecting these completeness conditions. We find that statistical (...) completeness motivates but does not imply Jarrett's completeness condition, because Jarrett's condition encodes further intuitions about locality and causality. We also dispute Ballentine and Jarrett's claim that EPR-completeness implies Jarrett's completeness condition. (shrink)

According to Popper and Miller [1983 and 1987], the part of a hypothesis that transcends the evidence is probablistically countersupported by the evidence. Therefore, inductive support is not probabilistic support. Their argument hinges on imposing the following necessary condition on ‘the part of a hypothesis h that goes beyond the evidence e’: that transcendent part, called k, must share no nontrivial consequences with e. I propose a new condition on k that is incompatible with Popper and Miller's condition. I then (...) show why the new condition is a viable alternative to Popper and Miller's. By doing so, I refute their argument that probabilistic support cannot be inductive. *I'd like to thank Michael Redhead. Jeremy Butterfield. and an anonymous referee for comments on earlier drafts. Thanks especially to David Miller for insightful criticisms. Adopted from work done in the Department of History and Philosophy of Science. University of Cambridge. 1989. (shrink)

Specker contradiction, I prove that ‘local realistic’ theories predict nontrivial violations of the quantum mechanical EPR-type perfect anticorrelations. The proof invokes the same stochastic local realism conditions used in Bell arguments. For a class of theories called ‘orthodox spin theories’, the perfect anticorrelations used in the proof emerge from rotational symmetry. Therefore, an orthodox spin theorist must abandon either the spirit of relativity, as encoded by local realism, or the letter of relativity, which demands rotational invariance.

Without invoking macrorealism, we derive a contradiction between the quantum mechanical predictions forsquid's and two intuitive conditions. First, we assume that asquid can be measured without significantly disturbing its subsequent macroscopic behavior. Second, we assume a trivial realism condition much weaker than Leggett's macrorealism. Quantum mechanics itself obeys our realism assumption. This proof suggests that althoughsquid experiments cannot rule out macrorealism, they can rule out most theories that allow noninvasive measurements.