It is supposed to be common knowledge in the history of ideas that one of the few medieval philosophical contributions preserved in modern philosophical thought is the idea that mental phenomena are distinguished from physical phenomena by their intentionality, their directedness toward some object. As is usually the case with such commonplaces about the history of ideas, especially those concerning medieval ideas, this claim is not quite true. Medieval philosophers routinely described ordinary physical phenomena, such as reflections in mirrors or sounds in the air, as exhibiting intentionality, while they described what modern philosophers would take to be typically mental phenomena, such as sensation and imagination, as ordinary physical processes. Still, it is true that medieval philosophers would regard all acts of cognition as characterized by intentionality, on account of which all these acts are some sort of representations of their intended objects.Mental Representation explores the intricacies and varieties of the conceptual relationships between intentionality, cognition and mental representation as conceived by some of the greatest medieval philosophers. The clarification of these conceptual connections sheds new light not only on the intriguing historical relationships between medieval and modern thought on these issues, but also on some fundamental questions in the philosophy of mind as it is conceived today.

Skepticism, Causality and Skepticism about Causality studies the interrelated themes of causality and skepticism in contemporary, early modern and medieval philosophy. Thomas Aquinas's celebrated proofs of the existence of God (the Five Ways of the Summa Theologica) rely in part on an Aristotelian notion of synchronous causality, wherein the things that exist and persist require an accounting that ultimately terminates in the ongoing activity of a first mover, as the existence and persistence of an ecosystem is traceable to the sun. By contrast, in David Hume's early modern account, causality consists in the regularity of successive events (a rolling billiard ball's collision with a stationary one is always followed by the movement of the latter). Moreover, Newtonian and Einsteinian accounts respectively suggest that motion, once initiated, requires no explanation. In light of these developments, the first set of essays in this volume re-evaluates the Aristotelian paradigm and its relation to modern science, contending that in some fields (such as ecology, thermodynamics or information theory) contemporary science still preserves some intuitions about causality that support Aquinas's deliberations.Hume's skepticism about causality is heir to late medieval and early modern development that transformed not only the notion of causality in general, but also the idea of the causal connections between our cognitive faculties, God, and the world in particular, giving rise to extreme, solipsistic forms of skepticism, such as Descartes' Demon skepticism. The second set of essays considers whether Aquinas's thought would be susceptible in some ways to this form of skepticism, and what motivated, just a couple of generations later, the turn to epistemology already involving this sort of skepticism.