"Common by Causality and Common by Predication: Avicenna and Aquinas on a Twofold Division of Principles"

This article examines Avicenna as the source of a distinction Thomas Aquinas employs repeatedly: the division of common principles into those common by causality and those common by predication. Although the distinction has roots in Aristotle, it is explicitly formulated by Avicenna, who uses it to clarify the principles proper to natural philosophy and metaphysics and to reserve demonstration of the First Mover to metaphysics. After considering its Aristotelian background and Avicenna’s account of the commonality of the four causes, the article traces Thomas’s adoption and expansion of the distinction in his commentary on the *Sentences*, *De veritate*, and his commentaries on Boethius’s *De trinitate* and Aristotle’s *Physics*. Thomas preserves Avicenna’s distinction while extending it to differentiate metaphysics from theology. This development illustrates both Avicenna’s refinement of Aristotelian thought and the importance of Avicennian philosophy for Thomas’s account of scientific principles.