Dylan Gault

Date of Award


Degree Type


Degree Name

Doctor of Philosophy




Bill Harper

Second Advisor

Wayne Myrvold


This thesis examines two recent research projects in cosmology with the aim of presenting them as a case study of the use of evidence in science. Descriptions of scientific reasoning commonly use language reminiscent of simple hypothetico-deductive methodology. However, a number of philosophers of science have argued that this model of scientific reasoning is inadequate. In particular, recent work has looked to the methodology of Isaac Newton for an addition to the standard hypothetico-deductive account. This methodology seeks to deliver a richer notion of empirical success through providing warrant for scientific claims on the basis of the ability of a theory to deliver agreeing measurements of its theoretical parameters from diverse and independent sources. One aspect of recent work in cosmology is the introduction of specific measurements of a positive value of the cosmological constant, A, a theoretical parameter that, prior to recent results, most cosmologists either ignored or assumed to be set at zero. This thesis claims that, in accordance with Newton's methodology, it is through the use of this richer notion of empirical success that the current research provides empirical support for the inclusion of the parameter and for the standard cosmological model in general.

The thesis examines the core of the course of cosmological reasoning regarding the relationship between observation and the mass-energy density parameters of the universe. Following an introductory chapter, Chapter Two reviews the standard cosmological model prior to the recent work on A, with a focus on the use of agreeing measurements in this research. Chapter Three reviews recent cosmological research on type la supemovae and the use of these events to produce measurements of cosmological


produce measurements of cosmological parameters. Chapter Five reviews the use of the agreement in the measurements produced by these theories and the nature of the empirical support that this agreement delivers to the standard cosmological model against systematic error and against alternative theories that may be potential rivals of the standard cosmological model.



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