Epistemology of a Theory of Everything

In this dissertation, I examine the debate between Hermann Weyl and Albert Einstein over Weyl's 1918 unified field theory, both for its own merit and for the epistemological implications it holds for the ultimate goal of physics: a theory of everything. I provide a detailed explication of Weyl's response to Einstein's objection, including a careful exegesis of Weyl's somewhat enigmatic distinction between the determination of physical quantities through persistence versus adjustment. I show that Einstein's concerns were ultimately more methodological in nature than has been previously argued in the literature, thereby providing a novel explanation for the apparent inconsistency he evinces in the well-known 1921 lecture, 'Geometry and Experience.' Seen in this light, the differences between Einstein and Weyl in this period appear rather small, especially regarding one of the central themes of the dispute: how to make a physical theory testable. They both argue that, in a fully-developed theory, the behavior of measuring devices should not be taken as given but rather derived from first principles; i.e., as composite objects able to determine the properties of more basic entities, rigid rulers and regular clocks should arise as particular solutions of the fundamental equations. I argue that this requirement, though important for explaining how theories can make claims about the world that are capable of test through observation, leaves the task half-finished. Equally important is the task of showing why those measuring devices should be considered observable in the first place. I conclude that if we demand that this also be done without arbitrary stipulation, then we will need a detailed, scientific account of the sense-organs we use to make observations, constructed on the basis of the first principles of the theory we wish to test.