Abstract

This dissertation gives an original account of the historical development of modern cosmology along with a philosophical assessment of related methodological and foundational issues. After briefly reviewing the groundbreaking work by Einstein and others, I turn to the development of early universe cosmology following the discovery of the microwave background radiation in 1965. This discovery encouraged consolidation and refinement of the big bang model, but cosmologists also noted that cosmological models could accommodate observations only at the cost of several "unnatural" assumptions regarding the initial state. I describe various attempts to eliminate initial conditions in the late 60s and early 70s, leading up to the idea that came to dominate the field: inflationary cosmology. I discuss the pre-history of inflationary cosmology and the early development of the idea, including the account of structure formation and the introduction of the "inflation" field. The second part of my thesis focuses on methodological issues in cosmology, opening with a discussion of three principles and their role in cosmology: the cosmological principle, indifference principle, and anthropic principle. I assess appeals to explanatory adequacy as grounds for theory choice in cosmology, and close with a discussion of confirmation theory and the issue of novelty in relation to cosmological theories.