Journal of the History of Philosophy

Journal of the History of Philosophy 39.1 (2001) 49-75

Sensible Ends:
Latent Teleology in Descartes' Account of Sensation

Alison Simmons

One of Descartes' hallmark contributions to natural philosophy is his denunciation of teleology. It is puzzling, then, to find him arguing in Meditation VI that human beings have sensations in order to preserve the union of mind and body (AT VII 83). ¹ This appears to be just the sort of teleological explanation that he proscribes. Descartes' Anglo-American commentators have had little to say about the teleological overtones of his claims about sensation. His French commentators acknowledge these overtones, but seem largely untroubled by them. ² It is worth pausing to be troubled, for a closer analysis reveals that Descartes' famous proscription against teleology is not as simple as it is generally thought to be. In the first half of this essay, I argue that Descartes advocates a genuinely teleological conception of the senses. My aim is not to charge Descartes with employing illicit teleology, but to argue that there is a place for teleology even in his revisionist natural philosophy. Accordingly, in the second half of this essay, I argue that Descartes' assault on teleological explanation is [End Page 49] not a sweeping assault on finality, but a more directed attack on particular uses of ends in natural philosophy. Descartes' assault leaves standing a form of teleological explanation that proves crucial to his own treatment of sensation.

1. Descartes' Rejection of Teleological Explanation at a Glance

A teleological explanation is one that purports to account for something in terms of its ends or its function relative to the ends of the system of which it is a part. Aristotle's physics provides many classic examples: plants produce leaves for the protection of their fruit; spiders spin webs in order to catch food; animals grow sharp front teeth and dull back teeth in order to facilitate biting and chewing respectively; eyes are for seeing. According to Aristotle, all natural phenomena are directed toward ends and no explanation is complete without a teleological component that specifies the end for the sake of which the phenomenon occurs. Indeed ends take explanatory priorityover other causes: "Both causes [the end and the matter] must be stated by the student of nature, but especially the end; for that is the cause of the matter, not vice versa." ³ And:

[T]he causes concerned in natural generation are, as we see, more than one. There is the cause for the sake of which [the end], and the cause whence the beginning of motion comes [the efficient cause]. Now we must decide which of these two causes comes first, which second. Plainly, however, that cause is the first which we call that for the sake of which. For this is the account of the thing, and the account forms the starting-point.⁴

In other words, Aristotle argues that natural substances have the matter they do, have the parts or organs they do, are organized as they are and act as they do for the sake of their ends. To explain why things are as they are, the natural philosopher must therefore explain the ways in which they contribute to ends.

Among the late scholastic Aristotelians familiar to Descartes there is considerable debate concerning the causal efficacy of ends. Genuine final causation, in which something is said to be acted on by an end, is limited to the intentional behavior of rational agents who consciously recognize their ends: only something that recognizes an end can be "moved" by one. Even here the sort of causation involved is peculiar: a rational agent is "moved" by an end insofar as the end induces a "metaphorical motion" toward (or desire for) the end in the agent's will. ⁵ While these scholastic Aristotelians resist attributing final causation [End Page 50] to non-rational creatures, they nevertheless persist in attributing ends to them. When Toletus, Rubio, the Coimbrans and Suarez take up the question whether nature acts propter finem, each answers it affirmatively: natural...