The epistemology of equivalence: symmetries and dualities

Thesis

Do symmetries and dualities invariably allow us to interpret the models they relate as equivalent? Interpretationalists answer yes, whereas motivationalists say no. This thesis examines the debate between these two camps. Ultimately, a moderate motivationalism that accommodates the most important interpretationalist insights is defended. Chapter 1 is an introduction. Chapter 2 lays the groundwork for the discussion to follow by developing a new account of theory interpretation. Chapter 3 examines interpretationalism and motivationalism about symmetries. The view defended is that symmetry-related models of a theory cannot ab initio be interpreted as equivalent. Rather, for this to be permissible, the theory must first be reformulated so as to yield a new theory that is (a) recognizably as explanatorily powerful as the original theory and (b) such that any two symmetry-related models are isomorphic. Contra stronger forms of motivationalism however, it is argued that the reformulated theory need not provide a perspicuous metaphysical picture of the ontology shared by the symmetry-related models. Chapter 4 examines how these reformulations are to be achieved. It argues that among the strategies available, reduction is a more powerful and versatile approach than is commonly appreciated. Chapter 5 develops an extension of motivationalism to the interpretation of models as physical. Chapter 6 extends the view defended in Chapter 3 to dual models. Finally, Chapter 7 defends motivationalism against objections derived from Hilary Putnam’s internal realism.

Authors: Ehrenfels, D

• DOI: 10.5287/ora-jban4dyjr
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: interpretationalism; reduction; relationalism; dualities; Putnam; interpretation; equivalence; comparativism; symmetries; motivationalism; conceptual relativity
• Subjects: Philosophy of Physics; Philosophy; Philosophy of Science