From Ontology to the Philosophy of Mind
In reconstructing Aquinas’s take on issues in the philosophy of mind, philosophers must begin with his account of the fundamental category in his metaphysics, which is the primary substance. Aquinas’s ontology is a world of individuals—a world, nonetheless, of individuals grouped as members of natural kinds. The discussions of Kripke and the earlier Putnam illustrate of several issues that drove Aquinas in considering how to categorize the world of individuals. The language of formal cause rigidly designates the ontological category of substantial form in a hylomorphic ontology. The individual is a member of a natural kind because its set of essential, sortal properties established through its substantial form determines the essential structure of the natural kind. This is a de re and not a de dicto account. Thus, the sortal properties are definitive of the kind in more than merely a linguistic sense. This individual is modified incidentally by a set of accidental forms. It is these forms that serve as the basis for the formal causality that Aquinas requires in order to explain the possibility of human knowledge. A substantial form, however, in opposition to Platonism, is always ‘embedded’ with matter in the space-time realm; it is never a stand-alone ontological entity or reified property.
Put differently, Aquinas’s question, given this metaphysical theory, is: how are these individual primary substances known? In other words, what kind of intentionality theory must one accept in order to explain the possibility of an awareness of these individuals? Aquinas appears to construct a block-by-block intentional edifice in the philosophy of mind; all the important objects of awareness come through the various faculties or cognitive dispositions of the external and internal senses leading up to the formation of a concept through the ingenious abstractive activity of the intellectus agens and then known by the intellectus possibilis.
Regarding sensation, what this account proposes is that the intentional form in the perception of a proper sensible—the esse intentionale—is identical with the structure of the causal incidental or accidental form in the primary substance. Hence, for Aquinas, ‘red’ has a causal structure in the world. What intentionality theory forces Aquinas to accept is that the knower is aware of the red—for example, in the Jonathan apple—by sharing in the form identically in an intentional but not an entitative manner. This is the ‘esse intentionale’ and ‘esse reale’ distinction. There is a strict isomorphism between the esse intentionale and the esse reale. This is what renders perception possible. Renaissance scholastics, to be sure, went through many contortions trying to explain this causal structure. The intentional form, it must be emphasized, is never the object of knowledge. It is the ‘a quo’ for perceiving, not the ‘id quod’ of knowing; in other words, the intentional form is that by means of which the thing in the world is known. From this it follows that Aquinas is not a sense datum philosopher. Furthermore, a phantasm is not the object of knowledge with the external senses. To identify a phantasm with a sense datum is a substantial category mistake. There is sufficient textual evidence demonstrating that a phantasm is associated only with the faculties of the internal sensorium—the imagination, the vis cogitativa, and the sense memory. A phantasm is never found in the external sensorium alone. This intentional analysis put forward by Aquinas depends radically on the theory of formal causality. This is a category difference in causal analysis from the paradigm of efficient causality adopted by the early modern philosophers with the corresponding entanglement of representative realism. Aquinas’s analysis of a metaphysical theory of form enables his theory to transcend the limits of perception theory enunciated in the texts of modern philosophy.
It is sufficient for now to have considered, albeit briefly, how Aquinas treated indirect realism. Throughout the remainder of this book, Aquinas’s direct realism will be analysed in detail. Obviously, indirect realism has been suggested only in a limited manner so far. One principal purpose of this book will be to establish direct realism. This will be true when the thesis of objective relativism is considered later in this study. Textually, Aquinas’s account repeatedly is removed from under the umbrella of indirect realism.
In contrast to the almost negligible worry about the possibility of indirect realism in perception theory, Aquinas provides detailed analysis and criticism of exaggerated realism or early Platonism. This problem is related to an analysis of the intellectus agens and the ‘coming to be’ of the universal in the mind. Transcendental Platonism is, in essence, related to concept formation through the process of anamnesis, which is Plato’s classic theory of recollection. Aquinas, on the other hand, roots every act of knowledge in the things of the common-sense world of experience. Hence, his analysis is opposed theoretically to positions that entail subsistent or transcendental objects of awareness. He argues against any theory of universalia ante rem, which entails Platonism. Much of Aquinas’s efforts in analysing the ontological requirements for epistemology were directed at refuting the need for ‘illuminatio divina’ and the ‘separate intelligences’ common to the Arabian philosophers. Historians suggest that during Aquinas’s time, various forms of divine illumination were defended vigorously at the University of Paris, by both the Latin Averroists and the Franciscan philosophers, especially Bonaventure. Recent work by Pasnau suggests that Aquinas may be a more significant figure in the tradition of divine illumination than many scholastic historians of philosophy have been wont to admit. Pasnau writes: Aquinas represents the end of a long tradition in western philosophy. All the great philosophers, until the end of the thirteenth century, had seen no way to explain the workings of mind without appealing to the supernatural.’ Pasnau argues that with Duns Scotus, the break with a supernatural ‘illumination’ is finally achieved. Scotus, Pasnau writes, ‘would propose a thoroughly naturalistic account of the working of the mind’, and hence ‘viewed from this perspective, Aquinas marks the end of the first chapter in the history of the philosophy ofmind’.
An analysis of the intellectus agens will occur near the end of this book. At that time, Pasnau’s intriguing suggestion about illuminatio divina and its connection with Aquinas’s intellectus agens will be discussed in more detail.
Nonetheless, Taylor and Herrera provide one of the better accounts refuting the divine illumination thesis, although they do not refer to Pasnau’s account directly.  The foil for their analysis is Smit, who argues that a form of divine illumination is the only consistent reductive analysis of the intellectus agens5 Taylor and Herrera argue that Aquinas, following insights from Averroes, held that the intellectus agens is able to utilize its ability for abstraction following the standard interpretation of Aristotle’s philosophy of mind, which is not reducible to Augustine’s divine illumination theory. Taylor and Herrera argue, moreover, that when Aquinas mentions the ‘divine light’ in referring to the intellectus agens, what he means is a use of primary causality, which would be similar to the continuous creation adopted by Descartes. This is the overall dependence that any created object has in Aquinas’s view of the world. This is not reducible to rendering the abstractive power of the intellectus agens into a divine cognitive operation.
-  Pasnau, Thomas Aquinas on Human Nature, 309.
-  Ibid., 310. In a review of Pasnau’s book, Kenny argues against this interpretation of Aquinas’s intellectus agens; see Times Literary Supplement (7 Mar. 2003); see also Anthony Kenny, Medieval Philosophy(Oxford: Clarendon Press, 2005), 164.
-  Richard Taylor and Max Herrera, ‘Aquinas’s Naturalized Epistemology’, in Social Justice: Its Theoryand Practice: Proceedings of the American Catholic Philosophical Association 79 (2005), 85-102.
-  Smit, ‘Aquinas’s Abstractionism’, 85-118.