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Perceptual Dispositions

Aquinas next begins an analysis of the dispositions involved in perception. The distinctions engendered from the discussion of concept formation and concept exercise are utilized in this discussion. In De Veritate, Aquinas considers the structure of a sense faculty as a potency:

Sense is not an active but a passive power. Not every power that has an act, which is an operation, is called active, for then every faculty of the soul would be active. But a faculty that is related to its object as an agent to a patient is called active, and that which is related to its object as a patient to an agent is called passive. Now sense is related to the sensible thing as a patient

to an agent, because the sensible thing alters the sense [____] Seeing, however, is accomplished

by the fact that the visible species is received in sight; and this is a sort of passivity or suffering. Sense is, therefore, a passive power. (De Veritate, q. 26, no. 4; emphasis added)

Aquinas addresses the relation of potency to act in the intentional act of sensation.

[. . .] we must take into account that, as in the intellectual cognition, so too in sensation, potency and act are each twofold. For what so far possesses no sense faculty but is due by nature to have one, is in potency to sensation. And what has the sense faculty, but does not yet sense, is in potency to actual sensation in the same way as we have seen in the case of acquired intellectual knowledge. Now, as a subject moves from primary potency [Disposition-1] into primary actuality [Disposition-2/Actuality-1] when it acquires knowledge through teaching, so too a subject’s primary potency to the possession of a sense-faculty is actualized by her birth. But whereas a sense faculty is natural to every animal—so that in the act of being generated, it acquires a sense faculty along with its own specific nature—the case is not the same with intellectual knowledge. This is not naturally inborn in human beings. It must be acquired through application. (Commentary on the Soul, no. 373; emphasis added)

Referring back to Aristotle after denying the possibility of cognitive innate ideas, Aquinas raises the following issues regarding the Disposition-2/Actuality-1 status of sense faculties.

This is what he means by saying that ‘the first change in the sensitive being’ is caused by the parent. The ‘first change’, he notes, is from sheer potency to the primary actuality. And it is due to the parent, because there is a power in the semen to actualize the sensible soul with all its capacities (including the cognitive capacities). Once an animal has been generated, it has its senses in the same way as a human person who has been taught possesses knowledge. And when it actually senses, it corresponds to the person who actually exercises her knowledge by thinking. (Commentary on the Soul, no. 374; emphasis added)

Aquinas stresses an important point, which will have a bearing on discussions about the individual acts of the external sensorium. He asserts that an external sense faculty, by the very fact that it exists as a functional faculty, is found in a state of Disposition-2/ Actuality-1. In other words, nothing more than the existence of the functional sense faculty is necessary in order to have a sense faculty disposed adequately or rendered properly ready to sense a particular type of object. Accordingly, the sense faculty, in its very state of existing is in the state of Disposition-2/Actuality-1. In effect, this is the structural reason why Aquinas will argue that the external sense faculties are ‘per se infallible’ regarding their proper objects. This concerns only an awareness of the proper or special sensibles in Aristotelian perception theory.

The above passage is important for understanding Aquinas’s theory of sensation and perception. Here he provides the essential structural difference between sense knowledge and concept-formation. This epistemological distinction consists in the fact that different concepts are not innate to the knower but must be acquired dispositions of the cognitive agent. On the other hand, the abilities or dispositions to have different sensations—understanding the meaning of ‘sensation’ here to be the object of the act of sensation and not the mental act of awareness itself—are structurally innate to the human perceiver. These sensation dispositions or abilities are to be understood in terms of a disposition to see colours, to hear sounds, to feel roughs and smooths, hots and colds, and so forth. A perceiver, therefore, insofar as she exists and functions well as a human person, by her very nature as a human being possesses Dispositions-2/ Actuality-1 type sense faculties. Possessing properly disposed sense faculties is part of what it means to be a member of the natural kind of human persons. On the other hand, regarding concepts a knower must acquire these Dispositions-2/Actuality-1

habits through experience by ‘application and discipline’. They are not innate. Aristotle indicated this distinction in his Metaphysics: ‘All potencies are either innate (such as the senses) or acquired by habit (such as the potency for playing the flute) or by learning (such as those involved in the arts)’ (Metaphysics, bk IX, ch. 5 (1047b31-4)).

In summary, therefore, the structural difference between sense knowledge and concept formation is that perceptual dispositions are, by nature, innate at the level of Disposition-2/Actuality-1 abilities. On the other hand, generic conceptual dispositions, which are dispositions to acquire further dispositions, are by nature innate only on the level of a Disposition-1 ability. From this it follows that the set of dispositional properties, which makes up the substantial forms common to all human beings, comprises both instances of Dispositions-1 and Dispositions-2. Aquinas noted that a sense is ‘natural’ to every animal. This implies that it is a part of its nature or essence. This is Aquinas’s notion of a natural kind. A human nature possesses the following:

  • (a) dispositional properties, which are capacities that need acquired dispositions to function well, e.g. the ability to know concepts—intellectual knowledge;
  • (b) dispositional properties, which are so constituted that they do not need further acquired dispositions in order to function well, e.g. the ability or faculty to sense—sense knowledge.

Aquinas denies the need for acquired dispositions for the senses. Yet it would appear that one might ‘train the palate’, as it were, through courses in gourmet cooking, or ‘train the ear’ through music appreciation courses. Aquinas appears not to consider such possibilities. These cases may pertain to an analysis of the vis cogitativa, which occupies the latter part of this book.

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