On inter-theoretic relations and scientific realism

This thesis addresses three contemporary debates in the philosophy of science: namely, scientific realism, emergence, and theoretical equivalence. The thesis brings logico-semantic tools of the analytic tradition—about syntactic and semantic construals of theories, and about extensions and intensions—to bear on these debates. The thesis has two parts: Part I (Chapters 1-3) lays out the overall framework about scientific theories, scientific realism, and emergence. Part II (Chapters 4-6) develops more detailed themes. Part I first gives a conception of a scientific theory (Chapter 1), using logico-semantic tools that will be used in the rest of the thesis. Chapter 2 then brings these tools to bear on the debate about scientific realism, by construing the continuity of theories as a matter of extensions. The resulting position is a modest scientific realism, according to which one is justified in believing what confirmed theories say about extensions but not, in general, about intensions. I dub it ‘extensional scientific realism’. Chapter 3 proposes an account of the distinction between ontological and epistemic emergence, based on an explication of the notion of ‘novel reference’. The ontological emergence of one theory from another is defined as the failure of an appropriate linkage map between the two theories to ‘‘mesh’’ with the two theories’ interpretations. In Part II, Chapter 4 first develops a notion of theoretical equivalence, and introduces duality in physics, as an appropriate isomorphism between theories. The Chapter discusses the relation between duality and theoretical equivalence in philosophy of science. Chapter 5 discusses the heuristic roles of dualities in theory construction. It develops a distinction between the theoretical and heuristic functions of scientific theories, and illustrates the heuristic function of duality in theory construction. Chapter 6 discusses how theories without a spacetime can lead to scientific understanding. To this end, the Chapter describes three theoretical tools that are often used in theory construction and which lead to understanding, both in cases with and cases without straightforward spacetime visualisation.