Date of Award


Degree Name

Master of Arts



First Advisor

Dr. Timothy McGrew

Second Advisor

Dr. Arthur Falk

Third Advisor

Dr. David Newman

Access Setting

Masters Thesis-Campus Only


In classical epistemology it is often assumed that the only means by which epistemic justification may be conveyed from one set of beliefs to another is by one of two means: deduction, or strict induction. Since many regard these as insufficient for justifying propositions not confined to sense data, beliefs about unobservables are still widely regarded as vulnerable to views of skepticism. In response to these views, I argued for a third means of justificatory conveyance in the form of explanatory inference. My goal was to demonstrate that, when properly explicated, explanatory inference provides virtual certitude to many of our nonbasic beliefs on grounds of basic tenets of probabilistic induction. This simultaneously involved arguing for the general thesis of indirect realism. In so doing, necessary conditions were proposed for explanatory inference. As a metalevel justification of the use of these conditions, two nonempirical criteria were employed. These criteria were corroborated by appeal to theorems of the probability calculus, but were also argued to stand on their own as self-justified in virtue of their inherently rational character. It was argued that, under the auspices of these principles, two skeptical counterproposals, phenomenalism and the Cartesian deceiver scenario, are implausible next to that of indirect realism.