The Vis Cogitativa and Primary Substance
The vis cogitativa is the principal sense faculty in Aquinas’s theory of perception. It is by the conditioned awareness of this faculty of inner sense that the individuals of the world are perceived as primary substances. Insofar as Aquinas affirms the existence of a world of individuals, he also provides the epistemological machinery by means of which a human perceiver can be aware perceptually of those individuals. Furthermore, because in Aquinas’s ontology a primary substance is always an individual of a natural kind, which natural kind is determined by the substantial form, the vis cogitativa is also the faculty whose conditioned awareness achieves perception of an individual as one belonging to a natural kind. In essence, the vis cogitativa explains, after a modified Gestalt fashion, the possibility of perception of primary substances. To reiterate a suggestion from an earlier chapter, using Strawson’s term, this analysis of Aquinas approaches ‘descriptive metaphysics’. This faculty of inner sense saves both epistemological realism and ontological realism for Aquinas.
This inquiry into the nature of phantasms is thus concluded. The logic of the concept of phantasm is such that a phantasm is never equated with a sense datum, only partially analysed as a sense image, and structurally never to be associated totally with the external sensorium alone. More constructively, a phantasm is an epistemological category connected with three distinct operations of inner sense. Obviously, the phantasm is critically important for Aquinas’s theory of perception. It is by means of phantasms that Aquinas, using a complicated and sophisticated intentionality of perception and faculty psychology, has endeavoured to explain the possibility of a human perceiver’s awareness of the world of individual primary substances. The phantasm is crucial in providing a conceptual analysis of the vis cogitativa. Perhaps it is the vis cogitativa that best argues against both the sense datum and the imago interpretations of the phantasm. Both of these interpretations demand that there be an object for each act of awareness. Yet the vis cogitativa does not itself have an object perceptible by means of the external sensorium. Rather, it is the faculty that actively contributes a conditioned awareness for interpreting the bundles of sensation perceived by the external sensorium. The structured mental act of the vis cogitativa is an essential part of Aquinas’s philosophy of mind. Without such a structure, it seems impossible to explicate consistently Aquinas’s theory of perception regarding an awareness of individuals. Phantasm-2 is the vehicle for this structured awareness through the vis cogitativa. Of course, the principal mainstay entity in Aquinas’s ontological realism is the primary substance.
What is driving Aquinas at this point is the following issue in the philosophy of mind: what must be the case in order for a human perceiver to be aware of primary substances? A primary substance—the individual of a natural kind—is the principal metaphysical category in Aquinas’s scheme of things, his ontological realism. A primary substance is a combination of materia prima and forma substantialis, modified by a set of accidental or incidental forms. Through a dialectic in his philosophy of nature, Aquinas argues that this Aristotelian realism is the best metaphysical account available for the things of the world. Each individual thing naturally occurring in the world is an instance of a natural kind. The forma substantialis determines the set of necessary properties that ‘define’ the category of the natural kind. In Aquinas’s ontology, materia prima is the principle of individuation.
Aquinas next asks: how can a human knower become aware of these primary substances? It is through the process of the external sensorium—the external senses and the sensus communis—that a human perceiver is aware of the set of incidental or accidental forms. It is through the rather complicated process of abstraction through the work of the intellectus agens and the intellectus possibilis that a human knower is aware of the essence rooted in the substantial form—the sortal properties—that determines the natural kind. However, if the principal ontological category is the individual—the primary substance—then it seems plausible that Aquinas would postulate some sort of cognitive process so that a human knower might be aware of this fundamental category. It is at this point that the vis cogitativa with its structured mental act of awareness using an intentio non sensata comes into play. It is with the vis cogitativa using Phantasm-2 that Aquinas melds his ontological realism with his epistemological realism. Moreover, it is through an analysis of the vis cogitativa with Phantasm-2 that he justifies the distinction between sensation and perception. It is, furthermore, by means of the vis cogitativa with the contribution of Phantasm-2 that he not only offers but also justifies a category difference between sensation and perception. The vis cogitativa provides a placeholder in Aquinas’s philosophy of mind that prevents a vacuum or lacuna from developing—i.e. how do we know the principal category in his ontological realism, the primary substance?
White perceptively points out the general lack of understanding of the cognitive as opposed to the moral or practical reasoning account of awareness Klubertanz generally accepts in his extensive study of the vis cogitativa. This position articulated by Klubertanz is opposed to the general thrust of the analysis undertaken in this book and especially in this chapter. The vis cogitativa is that faculty of inner sense that identifies an individual of a natural kind; this phantasm-structured awareness is then stored in the sense memory, from which the species intelligibilis is abstracted by the intellectus agens. Hence the cognitive function of the vis cogitativa as articulated and defended in this analysis indicates that this cognitive faculty of inner sense is far more important than Klubertanz acknowledged; nonetheless, Klubertanz’s study is one of the more extensive accounts of this faculty on inner sense published in the twentieth century. This present study, therefore, attempts to remedy these important theoretical shortcomings exhibited in the analysis put forward by Klubertanz and followed by many philosophers commenting on Aquinas’s philosophy of inner sense.
-  In his analysis of the vis cogitativa, White writes the following about the Klubertanz muddles in discussing Aquinas on inner sense: ‘George Klubertanz actually denies that the cogitative power representsthe nature of the individual to the intellect. According to Klubertanz, the imagination rather than thecogitative power is the source of the phantasm from which the intelligible species are abstracted; the cogitative power merely focuses one’s attention on the phantasm in the imagination’: Leo A. White, ‘Why theCogitative Power?, Proceedings of the American Catholic Philosophical Association 72 (1998), 224, n. 2.