This dissertation investigates the possibility of justifying simplicity principles in science. The labor of these projects is organized into three chapters. The first chapter introduces some of the key authors and issues in the history of simplicity in science. This chapter also gives a detailed discussion of the work of the 19th century physicists Le Verrier and Newcomb who played a crucial role in setting the stage for Einstein's theory of relativity. These examples are used to illustrate points in the following chapters. However, they play a specific role in the first chapter to show serious problems with a view defended by an important contemporary author, Richard Swinburne, that one version of the principle of parsimony contributes to the probability that scientific theories will be true. The second chapter elucidates the problems involved in specifying and measuring the simplicity of scientific hypotheses and theories. When simplicity criteria are employed in a scientific methodology, we find that simplicity judgments of one kind are always traded-off with simplicity judgments of another kind. We also find that the scientific project involves a delicate balancing of several aims. This analysis renders a valuable result: that some dogmas, in particular, the dogma that principles of parsimony are the final court of appeal in scientific theory selection must be jettisoned. I also find that it is misguided to ask the question of whether or not simplicity of some clearly specified kind is related to the truth. In point of fact, the legitimate questions about the justification of specific simplicity judgments in science are much more complex and nuanced than this. This becomes clear when it is seen exactly how different simplicity criteria are related to one another and to the various desiderata of science. The third chapter investigates which argument forms may be available to justify simplicity principles in science. In some cases it is nonsense to ask the question of how simplicity is related to the truth. However, we can investigate the forms of various arguments that may be given to justify methodological principles involving simplicity criteria. The results from the second chapter are employed in two ways. First, methodological principles stand in a tight-knit set of interrelations, so our analysis of justificatory argument forms must incorporate the complexity of these relations. Second, simplicity is extremely heterogeneous and since no conceptual reduction of all of the various simplicity criteria is possible, justificatory arguments must deal with clusters of interrelated principles. This result may have certain advantages and other disadvantages for inductive, transcendental, or inference to the best explanation approaches to the justification of simplicity. My analysis shows what will and what will not work for these possible approaches to the question of justification and shows what some of the systematic and metaphilosophical commitments would have to be were philosophers to pursue this project.

In the first chapter of this paper I focus on the general overview of Occam's Razor, and develop several interpretations and adaptations of Occam's Razor as a principle of simplicity. In the second chapter I apply these different interpretations in the Physicalism/Dualism debate, and critically assess the validity of these implementations of Occam's Razor in philosophy of mind. In the final chapter I give an overview of my discussion thus far, and make assertions about what my paper means for the usage of Occam's Razor's as a whole.