Abstract

This dissertation analyzes the differences in the epistemological foundations of two Thomistic philosophers, Desire Mercier and Jacques Maritain, regarding observational science in the late 19th and early 20th centuries. During Mercier's time, theoretical expressions were regarded as a mirror image of the world. The image became more accurate as more propositions--which were derived from experiment--were added to it. Conjecture played a part in the scientific process in that the scientists would form hypotheses before conducting an experiment. The connection among propositions at the theoretical level was a mathematical one. Maritain, however, wrote at a time in which scientists like Einstein had begun to conjecture not only at the level of experiment, but also at the level of theory. Einstein, for example, had replaced the use of Euclidian geometry to connect theoretical statements with the use of Riemannian geometry. ;Both Mercier and Maritain worked to connect the philosophical statements of Thomism to the form of physical science prevalent in their day. This dissertation argues that Maritain's epistemology is superior to Mercier's. Maritain's epistemological principles allow a more accessible connection between Thomism and theoretical physics. Such accessibility is not possible given the representationalist theory of knowledge developed by Mercier. For Mercier, the truth of a mental representation depends on how well it reflects the real world. Truth, for him, is not and cannot be a property of the real world; it is a property of a mental image. But Maritain presents an epistemology in which the mind actually becomes identical with the intelligible structure of real things. Maritain puts the location of truth in a place that is external to the mind; he thus acknowledges truth's superabundance and ultimate mysteriousness. ;The difference between the epistemological system of Mercier and that of Maritain shows itself in three consequences, each of which is explored in this dissertation. First, the difference necessitates disparate interpretations of the history of the relationship between metaphysics and observational science. Second, philosophy bears a markedly different relationship to observational science in the works of these two men. And, third, these two men construct different models of observational science