Howard argues that the existence of unitarily inequivalent representations in Quantum Field Theory presents a problem for structural realism in this context. I consider two potential ways round this problem: 1), follow Wallace in adopting the 'naive' Lagrangian form of QFT with cut-offs; 2), adapt Ruetsche's 'Swiss Army Knife' approach. The first takes us into the current debate between Wallace and Fraser on conventional vs. algebraic QFT. The second involves consideration of the role of inequivalent representations in understanding spontaneous symmetry (...) breaking and quantum statistics. In both cases, I suggest, the structural realist has sufficient room to manoeuvre. (shrink)

How can it be rational to work on a new theory that does not yet meet the standards for good or acceptable theories? If diversity of approaches is a condition for scientific progress, how can a scientific community achieve such progress when each member does what it is rational to do, namely work on the best theory? These two methodological problems, the problem of pursuit and the problem of diversity, can be solved by taking into account the cognitive risk that (...) is involved in theory choice. I compare this solution to other proposals, in particular T. S. Kuhn's and P. Kitcher's view that the two problems demonstrate the epistemic significance of the scientific community. (shrink)

Within the philosophy of science there has been a great deal of rather vague talk about the 'heuristic fruitfulness' (or what Peirce called the 'esperable uberty') of theories. It is my aim in the present paper to add some precision to these discussions by linking this 'fruitfulness' to the satisfaction of certain heuristic criteria. In this manner the demarcation between 'discovery' and 'pursuit' becomes blurred. As a case study, I present the competition between the paraparticle and colour models of quarks (...) in the late 1960s. I argue that the eventual appraisal of the latter as the more fruitful of the two was based on the incorporation of a particular symmetry principle, regarded as a heuristic guideline, rather than on non-epistemic factors concerning 'cognitive resources' and the like. (shrink)