Many arguments found in the physics literature involve concepts that are not well-defined by the usual standards of mathematics. I argue that physicists are entitled to employ such concepts without rigorously defining them so long as they restrict the sorts of mathematical arguments in which these concepts are involved. Restrictions of this sort allow the physicist to ignore calculations involving these concepts that might lead to contradictory results. I argue that such restrictions need not be ad hoc, but can sometimes (...) be justified by considering some of the metaphysical issues surrounding the question of the applicability of mathematics to physical reality. 1 Introduction 2 Rejecting inferential permissiveness 3 The agreement problem 4 Independent objections to the liberal view. (shrink)

Applied mathematics often operates by way of shakily rationalizedexpedients that can neither be understood in a deductive-nomological nor in an anti-realist setting.Rather do these complexities, so a recent paper of Mark Wilson argues, indicate some element in ourmathematical descriptions that is alien to the physical world. In this vein the mathematical opportunistopenly seeks or engineers appropriate conditions for mathematics to get hold on a given problem.Honest mathematical optimists, instead, try to liberalize mathematical ontology so as to include all physicalsolutions. Following (...) John von Neumann, the present paper argues that the axiomatization of a scientifictheory can be performed in a rather opportunistic fashion, such that optimism and opportunism appear as twomodes of a single strategy whose relative weight is determined by the status of the field to beinvestigated. Wilson's promising approach may thus be reformulated so as to avoid precarious talk about a physicalworld that is void of mathematical structure. This also makes the appraisal of the axiomatic method inapplied matthematics less dependent upon foundationalist issues. (shrink)