Abstract

Whether nature is or is not systematic sounds at first like an idle metaphysical question, but considered in relation to the aims of science and the methods of appraisal of scientific theories, it can be given clear content. It is also necessary to ask the question in order to study the relation of causation, laws of nature, and theoretical structure. ; Aims. The doctrines that science aims to provide explanations, that science achieves success in this aim, that explanation involves unification, and that the principles on which explanations, properly so-called, are based, must be true, together imply that nature is a system. For a kind of explanation she calls "causal", Nancy Cartwright affirms , and but denies ; for a kind of explanation she calls "theoretical", Cartwright affirms , and but denies . I show by historical examples that Cartwright's distinction between "theoretical" and "causal" explanation is often impossible to make out. I show, largely through discussions of Galileo and Newton, that Cartwright has a misleading view of the role of idealization in physical science, a view apt perhaps for physics before Newton, but not for Newtonian physics. I use my historical case studies to undermine numerous specific sceptical arguments by which Cartwright supports her novel conception of "theoretical" explanation. ; Methods. I argue that the Newtonian, "bootstrap" method in terms of which Cartwright reconstructs low-level experiment- and measurement-based inferences to specific causal conclusions has its clearest and most cogent applications in inferences to high-level theoretical conclusions. Newton's method, however, presupposes that nature is a system. Nature must be systematic in order to be well suited to study by the bootstrap method. I argue that the method has been notably successful, and that it consequently is appropriate to assimilate the method's substantive presupposition concerning natural systematicity to what has been learned from the experience of the method's successful application, and to say that we have evidence that this presupposition is true, that is, evidence that nature is systematic. ; Causation, Laws, and Theory. Against Cartwright I defend a top-down, anti-metaphysical conception of this relation, and an "internal realist" conception of theoretical structure. By highlighting some facets of the mathematics appertaining to fundamental physical laws presumed true, I argue that certain phenomena concerning scientific practice from which Cartwright's metaphysical view of causes gains apparent strength in fact are conformable to my own account