Representation and Scepticism from Aquinas to Descartes by Han Thomas Adriaenssen (review)

It is by now a truism that early modern debates are heavily indebted to their medieval antecedents. Just in what way, and to what degree, is controversial. Han Thomas Adriaenssen's excellent book follows its topics from the medieval controversy over species (according a chapter each to Aquinas and Henry of Ghent, Peter John Olivi, Peter Auriol, and Ockham) through the early moderns (Descartes, Malebranche, Arnauld, Robert Desgabets, and the English anti-Cartesian, John Sergeant). A final part gives an overview of the debates. Throughout, Adriaenssen's work achieves a high level of clarity and insight.

The chief subject of controversy is indirect realism, the view that an extra-mental object x "is cognized in virtue of the apprehension of a representational device y that is different from x" (21). Adriaenssen divides the problems it faces into two categories: criteriological and representational (222). The representational problems fall into two groups. First, we have the question whether an intermediary can direct the mind beyond itself. Critics argue that indirect realism slides toward idealism, with mental objects serving as the termini of acts of perception. Second, we find philosophers arguing that representations cannot resemble their objects to the degree necessary to serve as representations at all.

The criteriological problem is the worry, familiar from Berkeley to Putnam and Rorty, that indirect realism interposes a "veil of ideas" between subject and world and provides a launching pad for skepticism. But as Adriaenssen argues, following Steven Nadler and others, direct realism is no better off. As long as it allows for the possibility of illusion and error (which any theory must), direct realism is just as vulnerable to skeptical doubts as its counterpart. Each time one of his philosophers claims epistemic advantages for his form of direct realism, Adriaenssen is quick to point out its limitations (see, e.g. 53, 176, and 243). Adriaenssen argues that the medievals' epistemic optimism explains their comparative neglect of the criteriological problem; only with the rejection of the largely common-sensical ontology of the Aristotelians in the modern period do we see skeptical issues take a leading role.

Adriaenssen begins with Aquinas, arguing that, although at times equivocal, Aquinas's texts point to indirect realism, with species serving as the apprehended device. Nevertheless, these species are formally (if not materially) identical with those instantiated in the external world. In Adriaenssen's telling, Aquinas's critics treat species instead as "devices that, like imprints in sand, need to be interpreted by the subject" (107). This means their arguments often miss their target. Moreover, most of these figures (with the possible exception of Ockham) substitute their own apparatus to deal with non-veridical perception, imagination, and memory (witness Olivi's "memory species" (77), or Auriol's "apparent being" [98]). One is left with the impression that many of these departures from Aquinas are terminological and that there is not much substantive difference between the direct and indirect realisms of the medieval period; what differences there are appear to be primarily theological (79).

The second part of the book takes up the debate among the moderns. And here we reach the book's only weak point: Adriaenssen's attempt to resurrect the direct realist reading of Descartes. I was never clear exactly what Descartes's alleged direct realism was meant to consist in, nor why the interpretive maneuvers Adriaenssen shows are logically possible should be thought at all plausible. Adriaenssen rightly points out that Cartesian ideas are not a veil but a window; ideas "disclose the world" (54). But that is, of course, just what the indirect realist wants to say.

Adriaenssen is at his best in reconstructing arguments and showing how they persist, or are transformed, across figures and periods. To give just one example: Ockham questions the ability for species to serve as representations with his example of the statue of Hercules. The statue cannot serve as a representation of Hercules for anyone who has not already, by some other means, acquired...