St. Thomas Aquinas and the self-evident proposition: A study of the manifold senses of a medieval concept

Michael Vincent Dougherty, Marquette University


This dissertation is an historical and exegetical study of the concept of self-evidence as found in the works of the thirteenth-century philosopher and theologian St. Thomas Aquinas. I have sought to identify all of the explicit self-evident propositions found in the writings of the Angelic Doctor, to indicate the terminology of the discussions of self-evidence, and to provide a context for understanding the appeals to self-evidence in the corpus thomisticum . To this end, the dissertation is divided into six sections. The introduction of the dissertation presents an account of the general neglect the concept of self-evidence has received by many contemporary philosophers. The first chapter is an examination of Aquinas's various definitions or descriptions of self-evidence. By examining the various ways in which definitions can be formulated, it is argued that self-evidence can be viewed as an equivocal notion, for there are different senses in which terms can be defined. In the second chapter I turn to Aquinas's doctrine of intellectual habits to explain how Aquinas justifies some of the divisions of self-evident propositions into classes. I argue that, for Aquinas, the designation of a proposition as self-evident is always, in itself, an incomplete characterization, requiring that it be supplemented with a more specific account of the intellectual habit whereby the proposition can be cognized precisely as self-evident. The third chapter examines a significant epistemic problem surrounding the cognition of self-evident propositions. Particular attention is paid to Aquinas's often-neglected doctrine that the essences of material things are hidden to human beings. The fourth chapter returns to a presentation of intellectual habits as that which allows for self-evident propositions to be cognized as self-evident. I focus on the habit of faith, and examine some texts that suggest that the intellect can be fortified with supernatural habits. The final chapter examines Aquinas's views on the role of self-evident propositions in moral psychology and moral science. The seven explicit ethical self-evident propositions from Aquinas's writings are set forth and discussed, with particular attention to the nature of the practical syllogism in moral decision-making. A summary of findings completes the dissertation.

Recommended Citation

Dougherty, Michael Vincent, "St. Thomas Aquinas and the self-evident proposition: A study of the manifold senses of a medieval concept" (2003). Dissertations (1962 - 2010) Access via Proquest Digital Dissertations. AAI3093140.