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Descartes's Imagination: Proportion, Images, and the Activity of Thinking

University of California Press

In the introduction I mentioned Descartes's indebtedness to a tradition of philosophical psychology that placed so-called internal or inward senses between the five external senses and the powers of intellect. The purpose of this chapter is twofold: (1) to introduce the chief elements of the doctrine of the internal senses and situate the imagination within it and (2) to demonstrate the connection of the psychology and physiology of understanding elaborated in Descartes's Regulae ad directionem ingenii to this tradition. As we shall presently see, although at first glance the psychophysi-ology of the Regulae reads like an anticipation of the later theory of the pineal gland (as the seat of the soul in the body), it is in a more original sense an outgrowth of the doctrine of internal senses.

A. IMAGINATION AND THE INTERNAL SENSES BEFORE DESCARTES

Imagination is a name traditionally given to one of the powers of the mind enumerated in so-called faculty psychologies,1 which divide the human soul according to fundamental capacities. Most medieval discussions follow Aristotle in taking the vegetative, sensitive, and intellectual parts as

As pointed out by Jerry A. Fodor, although faculty psychology is pronounced dead in every century, it invariably recovers; see Fodor, The Modularity of Mind: An Essay on Faculty Psychology (Cambridge: MIT Press, 1983). The central issue for a psychology of faculties is not whether mind or soul is thought to have various functions but the degree of independence of these functions from higher powers. For example, if the senses are thought to operate in essential independence from intellect, then sensibility is an independent faculty; intellect, in its turn, might function independently of sense, for instance insofar as it does not require the immediate action of the senses. As soon as one allows even a small degree of independence to a function, one has in fact taken the first step into a psychology of faculties.

basic; Thomas Aquinas amplifies this to five by adding the appetitive (including will) and the locomotive powers.2 Each of these parts may in turn be subdivided according to its various functions and objects. The intellectual power, for instance, can be divided, according to its mode of operation, into intellect, which is immediately apprehensive, and discursive reason, which proceeds by stages; or, emphasizing instead the object toward which the faculty is directed, one can divide it into the three capacities of knowing (l) what is changing, (2) what is unchanging but material, and (3) what is unchanging and wholly immaterial.

The sensitive powers include not just the five external senses of sight, hearing, touch, smell, and taste but also the internal senses. Although there was no little disagreement about the precise number of the internal senses, their proper names, their organic locations, and the correct delimitation of their functions, there was sufficient consistency in medieval presentations for us to abstract a core theory. The core theory ultimately derives from Aristotle but has admixtures from other philosophical traditions and incorporates scientific and medical doctrine as well.

In a first approximation we should note that the sensitive powers, which human beings share with other animals, are intermediate between the vegetative-nutritive-reproductive powers possessed by all living things and the intellectual powers possessed (at least among physical beings) only by humans. In contrast to the vegetative powers, the sensitive powers involve an awareness of things, or at least of aspects of things. Awareness does not make them intellectual, for the intellectual powers proper operate at the level of abstractions, universal concepts, and generalizations, whereas the sensitive powers deal with sensory aspects of singular things. Still, there can be more than a superficial resemblance to understanding in animal sensibility. This is evident not so much from individual sensations—seeing a color, hearing a tone, smelling an aroma—as from the ability of animals to use multiple sensations of the same and different types, to compare and remember them, in order to survive and prosper. So, for example, most mammals learn from a small number of incidents to avoid situations that produce unpleasant effects, and they can make discriminations in their environment that permit them to secure food and shelter and to raise their young. Although some might be inclined to call these abilities forms of intelligence and to treat them as in essence intellectual, the tradition I am describing saw these as closer to the external senses than to intellect. Nevertheless, they opened the way to the conception of a deeper kind of sensibility that is crystallized in the internal sense tradition.

As I have already noted, the ultimate source of the internal senses doc-

Summa theologiae, 1, q. 78, art. 1.

trine is Aristotle's psychological writings, especially De anima (On the Soul). The second and third books of De anima develop a theory (beyond the vegetative) of the sensitive and cognitive powers of soul: the five external senses, the common sense (aisthesis koine ), imagination (phantasia ), receptive intellect (nous pathetikos ), and agent or productive intellect (nous poietikos ). This cognitive psychology was predicated on the existence of forms in substances (for our purposes 'substance' can be taken to mean physical objects, though for Aristotle there are immaterial substances, too): an essential form, which constitutes the nature of the thing and makes it the kind or species of thing it is (e.g., the form of human being), and sensible forms, which determine the various (many nonessential) sensible qualities of the thing (e.g., the visible form/shape of a particular human body).3 Sensible forms can be communicated to the properly disposed sense organs of animals, and they are divided into two kinds: proper sensibles, those things that are perceived by one and only one sense (color in vision, odor in smell, sound in hearing, etc.), and common sensibles, like movement, rest, figure, magnitude, number, and unity, which are communicated to more than one sense (e.g., both the eye and touch can detect figure).

It must not be thought that this communication of forms necessarily occurs through local motion or that it takes time, say by means of an "Aristotelian photon" flying through space from object to sense. Aristotle does not, for example, conceive of vision as being due to the transmission of little objects or impulses. Rather, a proper sensible in the object, for example its color, acts on the organ when the medium between them, in the case of color what Aristotle calls the diaphanous or transparent, is made actually transparent by light. In darkness, transparent materials are only potentially diaphanous, and so colors cannot be communicated to the eye; but light activates the medium, thus enabling it to be the means through which the sensible form communicates itself to the sense organ.4 The result is that the sense receives into itself the sensible forms of things without the matter.

To use the classic formula, the sense in act is the sensible...