The Awareness of the Individual as of a Kind
The analysis so far suggests that the vis cogitativa has two cognitive functions: (a) to be aware of an individual as an individual; (b) to recognize an individual as a member of a kind. Aquinas writes: ‘Hence, the vis cogitativa is aware of a human person as this human person.’ In his Commentary on Aristotle’s Metaphysics, Aquinas also explains this cognitive role of the mental act of the vis cogitativa.37
In human beings, the next thing above memory is experience, which some animals have only to a small degree. For an experience arises from the association of many singular [intentions] received in memory. And this kind of association is proper to human beings and pertains to the vis cogitativa [also called the particular reason], which associates particular intentions just as universal reason associates universal ones. (Commentary on the Metaphysics, no. 15)
In his Commentary on the Soul, Aquinas brings in the notion of awareness of a nature or natural kind. Moreover, he offers a distinction between instinct from the vis aesti- mativa and an awareness of an individual as a natural kind from the vis cogitativa. ‘The vis cogitativa apprehends the individual thing as existing in a common nature, and this is because it is united to intellect in one and the same subject [ . . . ] Instinct, on the other hand, is not aware of an individual thing as in a common nature’ (Commentary on the Soul, no. 398).38 Aquinas argues that the higher animals have some degree of ‘experience’ resulting from the workings of the vis aestimativa. Nonetheless, it is a difference qualitatively distinct from the reasoning abilities of the human knower.
Now since animals are accustomed to pursue or avoid certain things as a result of many sensations and memory, for this reason they seem to share something of experience, even though it be slight. But above experience, which belongs to particular reason [the vis cogitativa], human persons have as their chief power a universal reason by means of which they live. (Commentary on the Metaphysics, bk 2, no. 5)
This passage continues with the theme Aquinas articulated earlier that there are different degrees of awareness in the animal world. The highest level is similar to the reasoning ability in human knowers, but nonetheless it is qualitatively different, which he spells out in the following passage.  
Then he proves the superiority of art and science [ . . . ] Those who know the cause and reason why a thing is so are more knowing and wiser than those who merely know that it is so but do not know why. Now human persons of experience know that something is so but do not know the reason, whereas human knowers who have an art know not merely that something is so but also know its cause and reason. Hence those who have an art are wiser and more knowing than those who have experience. (Commentary on the Metaphysics, bk 1, no. 24)
Aquinas considers the reasoning ability to form intentionally and understand concepts with universal characteristics, which is appropriate to what he calls an art and a science. These latter cognitive abilities are unique to human knowers, and transcend the intentional possibility of knowing essences that exceeds the cognitive abilities of even the higher animals. He ends this section of his Aristotelian Commentary on the Metaphysics noted above with the following sentence: ‘For the purpose of natural instinct in animals is to direct them in their actions and passions, so as to seek and avoid things according to the requirements of their nature’ (Commentary on the Metaphysics, bk I, no. 15; emphasis added). What is interesting philosophically about this last sentence is Aquinas’s claim that the vis aestimativa works in animals ‘according to the requirements of their nature’ This would suggest that instinct, which is a part of the natural function of the vis aestimativa, is a component of the ‘nature’ of the animal and works in accord with the nature of the animal. Accordingly, it would be a dispositional property rooted in the substantial form of the animal’s essence. One might extrapolate from this phrase and apply it to the mental act of awareness unique to the vis cogitativa in human persons. It is ‘according to the requirements of their nature’ that humans are able to perceive individual particular things as members of natural kinds. This would be part of human nature as a dispositional property of the requisite substantial form. Without this structured awareness on the part of the vis cogitativa, a human knower would be deficient cognitively in at least two ways:
Without this structured awareness of the vis cogitativa, a human knower would be deficient in these two ways. Aquinas, to be sure, was not one to permit philosophical deficiencies to appear in his ontological accounts. It is to fill this epistemological gap that Aquinas postulates the unique act of awareness for the vis cogitativa. This saves the epistemological realism by which Aquinas accounts for the possibility of knowing the instances of the principal category in his ontological realism, namely, the primary substances that are individuals of natural kinds. This is an aspect of Aquinas’s explanatory methodology.
Throughout these texts, it is apparent that Aquinas links animal awareness with the rudimentary awarenesses of human beings. Aquinas is neither a Cartesian nor a dualist metaphysician. In Dependent Rational Animals, MacIntyre writes about this set of issues, which he believes philosophers have neglected for too long a time.
But some commentators [ . . . ] have failed to ask the relevant questions about the relationship between our rationality and our animality. They have underestimated the importance of the fact that our bodies are animal bodies with the identity and continuities of animal bodies, and they have failed to recognize adequately that in this present life it is true of us that we do not merely have, but are our bodies.
In the final chapter of Mind and World, McDowell addresses the issues that concerned MacIntyre:
Animals are, as such, natural beings, and a familiar modern conception of nature tends to extrude rationality from nature. The effect is that reason is separated from our animal nature, as if being rational placed us partly outside of the animal kingdom. Specifically, the understanding is distanced from sensibility. And that is the source of our philosophical impasse. In order to escape it, we need to bring understanding and sensibility, reason and nature, back together.
Both MacIntyre’s and McDowell’s search for better connections with the animal dispositions of human nature ring true for the fundamental ontological category of human nature adopted by Aquinas. Given these texts on inner sense from Aquinas, one notes immediately that Aquinas pays special attention to the knowing apparatus and the mental acts ofnon-human animals. This suggests strongly the anti-dualist characteristic of Thomas’s metaphilosophy. In writing ‘Anima mea non est ego’, Aquinas suggests that in no sense of the term is he a Cartesian dualist. He is working the same side of the ontological street as MacIntyre and McDowell. The analysis of inner sense as an intentional awareness of something beyond introspection enables the medieval philosophers to tease out these important non-dualist properties. Pasnau writes that the human mind is not equivalent to an angelic mind. It follows that any attempt to render Aquinas’s theory of mind into a form of dualism is fraught with structural and textual difficulties. Nonetheless, historians of psychology often treat Aquinas as a dualist. It is this interpretation of Aquinas as a proto-Cartesian dualist that this study refutes.
The vis cogitativa is Aquinas’s way to provide, almost in a teleological fashion, the necessary ingredients for a fully worked-out philosophy of mind enabling the human knower to function within the metaphysical scheme already provided by Aquinas’s ontological realism. What this suggests is that a human knower as knower is not cut adrift amid a sea of primary substances without the philosophy-of-mind machinery to know his way about. This is another indication that a modified Gibsonian method rooted in the evolutionary development of human sense organs is found analogously in Aquinas. Developing in this way enables a human knower to make his path around and through the environment. While Gibson’s theory does not have an ontology of primary substances, nonetheless he considers extensively the role the environment plays in determining how sense organs and faculties develop and function. The same metaphilosophy is found, mutatis mutandis, in Aquinas. To emphasize this point, we need to reflect on how Aquinas begins the following article in the Prima Pars of the Summa Theologiae that considers inner sense:
Since nature does not fail in necessary matters, there needs to be as many acts of the sensitive soul as may suffice for the life of a perfect animal. If any of these acts cannot be reduced to the same one principle, it follows that they must be assigned to diverse sensible powers. This is because a power of the soul is nothing more that the proximate principle of the soul’s operation. (Summa Theologiae, I q. 78 a. 4)
Aquinas suggests that the way the animal has adapted to its environment determines the number and function of the various sensitive powers—both the external and the internal senses. This is the meaning of his claim that ‘nature does not fail in necessary matters’. This in turn teases out the reliabilist and the externalist themes embedded in Aquinas’s philosophy of mind.
According to the texts in the Aristotelian Commentary, Aquinas argues that the vis cogitativa is aware of an individual as a member of a particular kind. This mental act, however, is neither identical nor coextensive with the mental act of abstraction found in the intellectus agens. An intellectual concept is an awareness of the ‘nature’ or ‘essence’ of a thing. This is the content of a natural kind; this nature is common to many individuals. Hence, it follows that an awareness of the individual concretum—an awareness of a primary substance—is precluded by its cognitive function from the mental act of the intellectus agens or the intellectuspossibilis. It is precisely at this juncture that the vis cogitativa comes into play. This inner sense faculty exemplifies a conditioned mental act able to be aware of an individual as a member of a ‘kind’. This does not mean that the mental act of the vis cogitativa is an awareness of a ‘nature’ or ‘essence’ This is the role of first intentional awareness on the part of the intellectus possibilis, which is the result of the abstractive process of the intellectus agens. In other words, the vis cogitativa is not aware of ‘human nature as human nature’, but rather as Megan the human person and Elin the human person. Suffice it to say now, however, that the phantasm peculiar to the vis cogitativa ‘conditions’ or ‘colours’ the mental awareness of the vis cogitativa so that it interprets the object in the external world in a unique way. Accordingly, this is a structured act of awareness. The structure of the act of awareness of the vis cogitativa is determined by an appropriate phantasm, which in turn comes about only because of the range of the perceiver’s experience. In other words, the vis cogitativa ‘interprets’ an object as an individual of a kind and not merely as a unified concrete whole consisting of a bundle of sense qualities. This still remains an externalist position on mind; what is known is the individual and not a concept or ‘social construction’ of an individual. Aquinas is neither an internalist nor a representationalist. In reading him, we must realize that what he proposes has a strong ‘un-Kantian’ flavour to it. While Aquinas does suggest a ‘structured cognitive mental act, other aspects of a Kantian position are avoided. There is no division between intuition and concept, no synthetic a priori schematization of concepts, and no simultaneous assertion of transcendental idealism and empirical realism. The thrust of the arguments in this study suggests an integrated account of intentionality, perception, vis cogitativa, and intellectus agens that provides a philosophically significant rival to Kantian approaches. Aquinas’s analysis offers explanatorily powerful and plausible philosophical resources of a significant un-Kantian kind. While Owens appears committed to the philosophical position that one is directly aware of individuals as individuals and not as collections of sensible qualities, it is unclear whether he would admit that the vis cogitativa is the faculty of inner sense by which this is explained. Nonetheless, Owens interprets Aquinas on perception as an externalist and as a realist.
An awareness of a bundle of proper and common sensibles is the object of the sensus communis. Hence, at the level of the intentional object of the sensus communis, Aquinas’s philosophy of mind is much like that proposed by Berkeley and Hume. It is with the vis cogitativa, however, that Aquinas transcends the limits of British empiricism. This, in effect, distinguishes the vis cogitativa from the sensus communis. Furthermore, this is evidence for placing the sensus communis in the external senso- rium and not in the internal sensorium, even though the sensus communis is classified by Aquinas as an internal sense. The cognitive content of the sensus communis is limited to what is attained through the external senses. Therefore, the sensus communis is part of the external sensorium. Because the vis cogitativa goes beyond the limits of the external sensorium, it is part of the internal sensorium. In Aquinas’s philosophy of mind, the distinction between the act of awareness of the sensus communis and the act of awareness of the vis cogitativa entails a substantive distinction between sensation and perception. Sensation is limited to an awareness of proper and common sensibles. Perception is that intentional process by means of which a perceiver is aware of the individual as a substantial individual of a natural kind. The paramount example of ‘inner sense’ for Aquinas, therefore, is the vis cogitativa. Nonetheless, it is instructive to note the general lack of discussion of this role of the vis cogitativa in most philosophical discussions of Aquinas’s theory of perception.