Includes bibliographical references and index.

Through species to the world: Aquinas and Henry of Ghent
Perception without intermediaries: Olivi's Critique of species
Direct realism about perception and beyond: Auriol and Ockham
Transformations of Cartesianism: Malebranche and Arnauld
Ideas and objects in Desgabets's radical Cartesianism
The solid philosophy of John Sergeant
From representation to object
Criteriological problems

In this book, Han Thomas Adriaenssen provides the first comparative analysis of the skeptical reception of representationalism in medieval and early modern philosophy. While Descartes is traditionally seen as the originator of a new form of skepticism by asserting that the direct objects of perception are mental images rather than external objects, Adriaenssen demonstrates that critics had already identified similar issues with Aquinas's theory of representation as early as the thirteenth century.