Editorial Note

Dennis W. Jowers is a senior majoring in philosophy in the College at the University of Chicago.

Metaphysics and the Question of Animal Intelligence in the Thought of Descartes

by Dennis W. Jowers

One might be surprised to learn that Descartes' Meditations on First Philosophy, a book whose avowed purpose is to demonstrate "the existence of God and the distinction between the human soul and body," contains so much discussion of non-human animals. [1] The Second, Third, Fourth, Fifth, and Sixth Objectors raise the subject of animals in order to counter Descartes' arguments for the incorporeality of the soul, its immortality, and even the existence of God. [2] All of these Objectors advance, either directly or indirectly, the notion that animals can think in their criticisms of Descartes; his spirited replies suggest that the subject was not unimportant to him. [3] Why, then, is the question of whether animals can think important for Cartesian metaphysics? The reasons will appear in starker contrast if we first examine some reasons that do not explain Descartes' attention to the subject of animal intelligence.

Descartes does not devote attention to animal intelligence out of concern that its existence would imply the falsehood of his principle of causality: i.e., the principle that all material or objective reality must proceed from some cause which contains at least as much reality either formally or eminently (the idea which undergirds Descartes' proofs of the existence of God from his idea of Him and from the necessity of a causa sui). [4] The Second Objectors raise the possibility of this principle's falsehood by noting that animals proceed from "sun and rain and earth, which lack life". The same animals, however, possess life, which is said to be "nobler than any merely corporeal grade of being". [5] Descartes responds by simply denying the notion that "life" is nobler than inanimate being. In accordance with his mechanistic philosophy, he holds the body to be "nothing but a statue or machine made of earth," and apparently thinks this conclusion sufficiently well established that he need not defend it at length. [6]

Descartes, likewise, does not deny that beasts have reason so vehemently because such a conclusion would directly imply the corporeality of the soul. Descartes grants that if thought consists of nothing more than corporeal motion, then animals do possess the same sort of reason as humans, although in a lesser degree. [7] But he vigorously denies the converse: the notion that if animals possessed thought, then thought would constitute nothing more than corporeal motion. On the contrary, he claims that if animals have reason, then they must have immortal souls and cites the Platonists and Pythagoreans in support of the reasonableness of this inference. [8]

Here lies the problem. According to Descartes, if animals can think, then they must have immortal souls. If the fact that I think proves that I have a soul, then, according to Descartes, the fact that animals think would prove that they have souls. Such a conclusion would be so counterintuitive and grossly contrary to Christian theology that it would call into question Descartes' entire philosophy and, in particular, his proof of the immateriality of the soul. If Descartes is right in ascribing immateriality to the soul, then the investigation of the soul, just as much as God, belongs to the realm of metaphysics. If this is so, then the question of whether animals can think strikes to the very heart of metaphysics.

Descartes is, therefore, justified in addressing the subject of animal intelligence and, indeed, would be negligent if he ignored it. In order to prove that animals cannot think, Descartes advances several plausible arguments; they cannot use language (or so he says), their behavior is not terribly adaptable, their supposed exhibitions of intelligence are instinctive, etc. But one argument stands out from the rest. Because all of the other arguments constitute premises of this more dramatic argument, we shall confine our attention to it and examine the others in the course of criticizing it. In a letter to the Marquess of Newcastle, Descartes claims that if one concludes that any animals think, one, if he thinks consistently, must hold that all animals think "because there is no reason to believe it of some animals without believing it of all, and many of them such as oysters and sponges are too imperfect for this to be credible." [9] Descartes does not even attempt to explain why a person who ascribed souls to apes or dogs would, for the sake of consistency, have to draw the same conclusion about oysters. Instead, he immediately quits his discussion of intelligence in animals on the pretense that he is "boring" his interlocutor. [10]

In the Second Set of Replies, Descartes expands this claim by asserting that "it is certain that [animals] have no perfection which is not also present in inanimate bodies". [11] It follows, therefore, that any argument, derived from the observation of nature, which purported to prove that dogs or apes have reason would apply with the same force, not only to sponges, but even to rocks. The quick abandonment of the discussion in the letter to the Marquess of Newcastle may indicate some lack of confidence in his analogy between higher and lower animals. The fact that Descartes only mentions this argument, in its more radical form, in one sentence of his Second Set of Replies lends further support to the verdict that Descartes himself mistrusts this argument. Such a dismissal, however, would be overly hasty. Upon closer analysis, the "if apes, then oysters, then rocks" argument appears to have some merit.

Descartes believes that his other arguments for animal automatism are so powerful that a person can defend the intelligence of higher animals against his attacks no more cogently than he could defend the intelligence of sponges. He uses the nearness of higher animals to humans, which seems to contradict the ape and sponge analogy, as an argument against the existence of mental activity on their part. If one objects that animals perform some tasks better than humans, Descartes responds that the very perfection of the animal's acts render it less likely that it thinks. As Descartes notes in Olympian Matters, a collection of thoughts compiled around the time of his famous dreams, "the high degree of perfection displayed in some of their actions makes us suspect that animals lack free will". [12] In addition, Descartes turns the superiority of animals in some areas to his advantage by pointing out the comical alteration between seemingly brilliant maneuvers and crassly stupid ones. The animal does some things skillfully, Descartes answers, because he is equipped for those things with an infallible instinct which cannot aid him in different circumstances. A person may claim, reasons Descartes, that animals do some things well by virtue of their intelligence, but he surely cannot explain how this intelligence strangely departs from them in so many different situations. [13] Descartes also argues that the similarity between humans' and beasts' organs make mental states in animals unlikely. Since even idiots can use signs to communicate "something pertaining to pure thought, and not to natural impulse," animals too, if they were intelligent, could use their human-like organs to communicate some information "relevant to particular topics, without expressing any passion." [14] So Descartes has strong reasons for believing that the similarity of some to human beings fails to imply a scale of levels of mental activity rising as one turns from lower to higher animals. On the contrary, animals' anthropoid qualities underscore Descartes' stark division between humans and all other forms of life.

At least four objections against Descartes' analogy of higher animals with lower animals relate to the higher animals' status relative to humans. First, one may claim that higher animals' apparently purposive behavior evidences some mental activity which sponges lack. A beaver, with no formal education, may be more adept at some aspects of engineering than a student of that subject. If this excellence were due to sheer intelligence, however, the beaver would similarly excel the student in composition and chess. The beaver's skills, therefore, have nothing to do with his putative intelligence. A persistent objector would point out that this same argument could be urged with equal success against the claim that, say, a welder is intelligent. Any welder could perform his work better than a novelist could. It does not follow from this that any welder could write better novels. Descartes' argument, therefore, seems to condemn the mass of humanity to mindlessness.

In this case, Descartes cannot simply attribute the welder's skill to instinct; no one is born knowing how to weld plates of iron together. But a welder can learn his trade by understanding the actions required and modifying the relations between his mental states and the actions of his glands so that he becomes deft at the required motions. Indeed, according to the explanation of the first of Descartes' Rules for the Direction of the Mind, the welder's learning of his trade actually renders him less capable of mastering other arts and sciences. [15] So the welder need not have inherited a disposition for welding and does not prove himself sub-human by displaying more aptitude in one area than in others.

Gassendi, however, points out that animals too acquire skills for which they have no genetic predisposition (he claims to have seen "a dog matching his barks to the sound of a trumpet, so as to imitate all the changes in the notes, whether sharp or flat, or slow or fast"). [16] Furthermore, they appear to 'learn' these skills in much the same way that humans learn them. [17] While this may not prove that animals think, an objector might argue, this human-like acquisition of skill by animals is much more advanced than anything displayed by sponges and oysters, not to mention rocks. Descartes argument, therefore, that if the former are intelligent, the latter must be also, seems absurd. We should be wary, however, of regarding such an argument as conclusive. These kinds of intuitions are the very things that make Descartes' analogy such a rhetorically effective argument. Descartes would deny neither of the objector's premises, viz., that animals appear to learn in much the same way as humans do and that oysters emphatically do not. What he claims is that animals display such vivid indicators of mindlessness that in order to attribute intelligence to them, one would have to be ignorant of their behavior, to rely on prejudice, or to waive the empirical evidence altogether. In the third case, the defender of animal intelligence would have no reason to deny the same to sponges and rocks. In order to validate his objection, therefore, Descartes' opponent would have to prove that the person who attributes intelligence to animals, after considering all the known facts about their behavior, is relying on something more substantial than prejudice. Such a validation, in turn, would require proof of at least one of three propositions: first, that animals can actually adapt to many different situations; second, that animals' learning requires something more than the conditioning of their passions; or, third, that animals can use language. The first proposition is scarcely tenable. In light of that weakness, the second seems unlikely as well. If one knew that animals possessed minds, one would not hesitate to affirm that they think while they learn. People have good reason to believe, however, that animals do not possess minds. The animals also, as far as anyone knows, do nothing which requires mental activity. So the wise objector would attempt to refute Descartes' analogy-with-oysters argument by showing that animals use language.

The objector could not succeed, however, without altering Descartes' definition of language. For Descartes, to use language is not merely to communicate, but to use "words, or other signs that are relevant to particular topics without expressing any passion." [18] The objector would be hard pressed to produce examples of such a feat performed by animals. They do indeed indicate what passions they are presently experiencing, but they do not devise ways of telling humans about their future or past desires or about remote subjects or generalizations they may have formed. [19] The objector may point out, correctly, that many actions performed by animals would be considered linguistic if performed by humans, but that does not prove that these actions are genuinely linguistic. In the case of human beings, observers consider communicative actions linguistic, because they know that the people performing them can think; observers have no such knowledge in the case of animals. If the objector responds (as Gassendi does) that animals are not human beings and thus should not be expected to speak with them, Descartes would refute him by appealing to the nature of animals. [20] Those that appear to be the most intelligent interact closely with humans, rely on the humans for their sustenance, and communicate a multitude of passions to them. Furthermore, higher animals are able to scratch, paw, rub, lick, cry, inflect their cries, etc. while human invalids have far fewer potentially communicative tools. Yet the invalids express their thoughts through language while the animals do not. [21] Once again, the higher animals' outward similarity to humans paradoxically moves the likelihood of their intelligence closer to that of sponges.

The objector may argue, finally, that one may more reasonably ascribe mental states to higher than to lower animals , because higher animals have brains which lower animals lack. According to Descartes, a person's mind remembers something when it (or, rather, its pineal gland) disperses animal spirits throughout the brain until they reach the pores in the brain where the imprints of previous consideration of the thing remain. [22] Likewise, a person imagines something new only when his animal spirits reach certain pores of the brain which allow some new image to be formed. [23] A setter, therefore, may have a mind, but be incapable of using language, because his brain is so defective that he cannot imagine new signs, or combine ordinary actions to make signs, or remember what certain signs signify long enough to exhibit a consistent pattern which would make them intelligible. The setter's inability to adapt to different circumstances may also arise because of some brain defect which impedes his imagining of possible new behaviors or his remembrance of the imagined behaviors long enough to execute them. God could create such brains without making Himself a deceiver, because He need not give the animals the faculty of judgment whose conclusions alone may legitimately be termed true or false. [24] The possibility that inferior brains make animal thinking imperceptible to human beings does not establish the fact of animal intelligence. It does, however, make, say, thinking by apes more probable than thinking by oysters and sponges, not to mention rocks. These latter organisms lack the most elementary cerebral organization which makes mind-body interaction possible. So to say of an oyster that it has a Cartesian mind is to equivocate in one's definition of oyster. Nothing would connect the hypothetical oyster mind to the tiny organism in a shell which we typically name 'oyster'. The hypothesis of animal intelligence, therefore, does not seem to imply that of oyster and rock intelligence.

If one grants Descartes his definitions of mind, thought, and language and his account of mind-body interaction, his argument for animal automatism fares well. His contention that "there is no reason to believe...[that]...some animals...[think]...without believing it of all," however, is false. [25] The dramatic physiological differences between dogs and oysters make this argument striking; they also prove it wrong. Even such a strict dualism as Descartes' does not allow one to ignore an animal's brain when assessing the likelihood that it has a mind.

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Editorial Note

Metaphysics and the Question of Animal Intelligence in the Thought of Descartes

by Dennis W. Jowers

Copyright (c) 1999 Dennis W. Jowers, All Rights Reserved

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