Steven French

Dispositionalist accounts of scientific laws are currently at the forefront of discussions in the metaphysics of science. However, Mumford has presented such accounts with the following dilemma: if laws are to have a governing role, then they cannot be grounded in the relevant dispositions; if on the other hand, they are so grounded, then they cannot perform such a role. Mumford’s solution is drastic: to do away with laws as metaphysically substantive entities altogether. Dispositionalist accounts are also deficient in that they either make no mention of the significant role of symmetries in science, or attempt to inappropriately eliminate this role. Here we shall attempt to motivate a structuralist view of laws by showing how it evades Mumford’s dilemma and accommodates the role of symmetry principles. In addition we shall consider how this view deals with a number of issues that dispositionalism finds problematic and indicate how the supposed necessity of laws and the explanation of relevant counterfactuals look from this structuralist perspective.

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.