Neo-scholastic Philosophy and Recent Work in Perception Theory
Given the emphasis on the philosophy and theology of Aquinas by the neo-scholastic movement during the last part of the nineteenth and the first half of the twentieth centuries, certainly one might wonder whether Aquinas’s position on sensation and perception had not been discussed sufficiently. Certainly much has been written about the philosophical and theological system of Aquinas. Nonetheless, there is little existing analysis in detail of his theory of sensation and perception. Much neo-scholastic writing dealt principally with Aquinas’s ontology. When epistemological issues were discussed, much effort went into rendering Aquinas’s account significant in light of the critical problems raised by Kant together with the sceptical problems posed by Descartes and several empiricists. Moreover, for the most part, epistemological accounts in neo-scholasticism were directed towards explaining the formation of the species intelligibilis by abstraction using the intellectus agens and concept formation and concept awareness with the intellectus possibilis. Like poor cousins, sensation and perception theories seemingly were treated only as incidental material propaedeutic to the analysis of intellect. Little conceptual analysis on sense knowledge is found in these writings. In fact, Aquinas himself suggests this focus in the Prima Pars of the Summa Theologiae. In addition, at the moment, a book-length monograph utilizing the techniques of analytic philosophy solely on Aquinas’s texts dealing with sensation and perception does not exist. This study intends to fill this lacuna by providing an analysis using the methods appropriate to the structural history of analytic philosophy. The closest book undertaking this analytic project is Pasnau’s Thomas Aquinas on Human
Nature. Yet Pasnau, while treating the external senses in some detail, spends less time with the ‘internal sensorium’ of Thomas’s theory. Likewise, Stump’s treatise spends little time on perception issues. Brian Davies’s well-received The Thought of Thomas Aquinas is at best cursory on the issues in the philosophy of mind. Kerr’s two recently published books on Aquinas, while covering many issues central to the thought of Aquinas mostly from a philosophical perspective, nonetheless render precious little content regarding sensation and perception. 
This book differs, therefore, from the general pattern exhibited in Aquinas research and scholarship by rendering a thorough and conceptually coherent account of Aquinas’s exposition of sensation and perception as found in his Commentary on Aristotle’s ‘On the Soul’. In addition, Aquinas’s position on the necessary conditions of his thesis of inten- tionality is spelled out more completely in this Aristotelian commentary. In general, one can make this claim without taking sides in the long-standing debate—more common at mid-twentieth century than at present—over whether the ‘real’ Aquinas is to be found in the Aristotelian Commentaries or in the two Summae: the Summa Theologiae and the Summa Contra Gentiles.2 The most that this book suggests on this debate is that on the specific question pertaining to a coherent analysis of the necessary conditions for his exposition of sensation and perception, Aquinas provides a more fully developed and sophisticated account in his Commentary on Aristotle’s ‘On the Soul’ than can be discovered in either the Summa Theologiae or the Summa Contra Gentiles. This present study, therefore, will pay close attention to the development of his theory of sensation and perception as elucidated in the Aristotelian commentary. In the manner of an explicatio textus, the following chapters often will follow the ‘logic’ of Aquinas’s narrative as presented in the Commentary On Aristotle’s ‘On The Soul’.
Because matters pertaining to perception theory did not affect theology directly (or so Aquinas thought), in the Summa Theologiae one should not expect a thoroughly developed monograph on sensation and perception. Nonetheless, his extensive commentary on Aristotle’s account of the soul fills whatever lacuna remains in the Summa Theologiae. This is a principal reason why the Commentary on the Soul serves as the primary text for this study and analysis. While the Quaestiones Disputatae De Anima, De Veritate, and the Summa Contra Gentiles also consider several of these issues, with several texts from these three works among others being incorporated into the fabric of this study, nonetheless the Commentary offers a more structured development of the issues central to sensation and perception. Stump argued that Aquinas’s account of mind and mental acts illustrate a ‘scattered development’ but one that is nonetheless a ‘systematically unified theory’. This unity depends upon the ontological theory on which the theories of mind and of knowledge rest. Regarding many issues in the philosophy of mind, this is a correct account; in the Commentary, however, Aquinas proceeds in a structured manner and provides a unified analysis of sensation and perception. This is another reason that this specific study devotes so much time to the Commentary rather than to the other scattered works.
-  Eleonore Stump, Aquinas (London: Routledge, 2003), chs 7 and 8.
-  Brian Davies, OP, The Thought of Thomas Aquinas (Oxford: Clarendon Press, 1992).
-  Fergus Kerr, OP, After Aquinas (Oxford: Blackwell, 2002); Kerr, Contemplating Aquinas.
-  Mid-20th-c. scholastic philosophers like Ramirez, De Koninck, and Oesterle held the former position,while Gilson and Pegis, with Owens more nuanced, among others, adhered to the latter interpretation. SeeVernon Bourke, ‘Thomas Aquinas, St’ in Paul Edwards (ed.), The Encyclopedia of Philosophy (New York:Macmillan, 1967), vol. 13, 106; this is a somewhat dated but still useful general account.
-  Stump, Aquinas, 21; one might argue that several philosophical positions in Aquinas’s writings appear‘scattered’. This is probably because Aquinas both wrote and dictated quickly.