We suspect that the answer is: as a result of an unthinking adherence to a mutant form of Cartesianism. It was a characteristic feature of Cartesian dualism to ascribe psychological predicates to the mind, and only derivatively to the human being. Sherrington and his pupils Eccles and Penfield cleaved to a form of dualism in their reflections on the relationship between their neurological discoveries and human perceptual and cognitive capacities. Their successors rejected the dualism – quite rightly. But the predicates which dualists ascribed to the immaterial mind, the third generation of brain neuroscientists applied unreflectively to the brain instead. It was no more than an apparently innocuous corollary of rejecting the two-substance dualism of Cartesianism in neuroscience. These scientists proceeded to explain human perceptual and cognitive powers and their exercise by reference to the brain’ s exercise of its cognitive and perceptual abilities.
The ascription of psychological attributes to the brain is senseless
It is our contention that this application of psychological predicates to the brain makes no sense. It is not that as a matter of fact brains do not think, hypothesize and decide, see and hear, ask and answer questions. Rather, it makes no sense to ascribe such predicates or their negations to the brain.14 The brain neither sees, nor is it blind – just as sticks and stones are not awake, but they are not asleep either. The brain does not hear, but it is not deaf, any more than trees are deaf. The brain makes no decisions, but neither is it indecisive. Only what can decide can be indecisive. So, too, the brain cannot be conscious; only the living creature whose brain it is can be conscious – or unconscious. The brain is not a logically appropriate subject for psychological predicates. Only a human being and what behaves like one can intelligibly and literally be said to see or be blind, hear or be deaf, ask questions or refrain from asking.
Our point, then, is a conceptual one. It makes no sense to ascribe psychological predicates (or their negations) to the brain, save metaphorically or metonymically. The resultant combination of words does not say something that is false; rather, it says nothing at all, for it lacks sense. Psychological predicates are predicates that apply essentially to the living animal as a whole, not to its parts. It is not the eye (let alone the brain) that sees, but we see with our eyes (and we do not see with our brains, although without a brain functioning normally in respect of the visual system, we would not see). So, too, it is not the ear that hears, but the animal whose ear it is. The organs of an animal are parts of the animal, and psychological predicates are ascribable to the animal as a whole, not to its constituent parts.
Neuroscientists’ ascription of psychological attributes to the brain may be termed ‘the mereological fallacy’ in neuroscience
Mereology is the logic of part/whole relations. The neuroscientists’ mistake of ascribing to the constituent parts of an animal attributes that logically apply only to the animal as a whole we shall call ‘the mereological fallacy’ in neuroscience.15 The principle that psychological predicates which apply only to human beings (or other animals) as wholes cannot intelligibly be applied to their parts, such as the brain, we shall call ‘the mereological principle’ in neuroscience.16 Human beings, but not their brains, can be said to be thoughtful or thoughtless; animals, but not their brains, let alone the hemispheres of their brains, can be said to see or not to see, to hear or not to hear, to smell or not to smell and to taste or not to taste things; people, but not their brains, can be said to be decisive or to be indecisive.
It should be noted that there are many predicates that can apply both to a given whole (in particular, a human being) and to its parts, and whose application to the one may be inferred from its application to the other. A man may be sunburnt, and his face may be sunburnt; he may be cold all over, so his hands will be cold too. Similarly, we sometimes extend the application of a predicate from a human being to parts of the human body; for example, we say that a man gripped the handle, and also that his hand gripped the handle; that he slipped, and that his foot slipped. Here there is nothing logically awry. But psychological predicates apply paradigmatically to the human being (or animal) as a whole, and not to the body and its parts. There are a few exceptions, such as the application of verbs of sensation like ‘to hurt’ to parts of the body – for example, ‘My hand hurts’, ‘You are hurting my hand’.17 But the range of psychological predicates that are our concern – that is, those that have been invoked by neuroscientists, psychologists and cognitive scientists in their endeavours to explain human powers and their exercise – have no literal application to parts of the body. In particular, they have no intelligible application to the brain.
3.3 Qualms Concerning Ascription of a Mereological Fallacy to Neuroscience
Methodological objections to the accusation that neuroscientists are guilty of a mereological fallacy
If a person ascribes a predicate to an item to which the predicate in question logically could not apply, and this is pointed out to him, then it is only to be expected that he will indignantly insist that he didn’ t ‘mean it like that’. After all, he may say, since a nonsense is a form of words that says nothing, that fails to describe a possible state of affairs, he obviously did not mean a nonsense – one cannot mean a nonsense, since there is nothing, as it were, to mean. So his words must not be taken to have their ordinary meaning. The problematic expressions were perhaps used in a special sense, and are really merely homonyms; or they were analogical extensions of the customary use, as is indeed common in science; or they were used in a metaphorical or figurative sense. If these escape routes are available, then the accusation that neuroscientists fall victim to a mereological fallacy may be unwarranted. Although they make use of the same psychological vocabulary as the man in the street, they are using it in a different way. So objections to neuroscientists’ usage based upon the ordinary use of these expressions are irrelevant.
Things are not that straightforward, however. Of course, the person who misascribes a predicate in the manner in question does not intend to utter a form of words that lacks sense. But that he did not mean to utter a nonsense does not ensure that he did not do so. Although he will naturally insist that he ‘didn’ t mean it like that’, that the predicate in question was not being used in its customary sense, his insistence is not the final authority. The final authority in the matter is his own reasoning. We must look at the consequences he draws from his own words – and it is his inferences that will show whether he was using the predicate in a new sense or misusing it. If he is to be condemned, it must be out of his own mouth. So, let us glance at the proposed escape routes that are intended to demonstrate that neuroscientists and cognitive scientists are not guilty of the errors of which we have accused them.18
First objection (Ullman): the psychological predicates thus used are homonyms of ordinary psychological predicates, and have a different, technical, meaning
First, it might be suggested that neuroscientists are in effect employing homonyms, which mean something altogether different. There is nothing unusual, let alone amiss, in scientists introducing a new way of talking under the pressure of a new theory. If this is confusing to benighted readers, the confusion can easily be resolved. Of course, brains do not literally think, believe, infer, interpret or hypothesize, they think*, believe*, infer*, interpret* or hypothesize*. They do not have or construct symbolic representations, but symbolic representations*.19
Second objection (Gregory): the psychological predicates thus used are analogical extensions of the ordinary expressions
Second, it might be suggested that neuroscientists are extending the ordinary use of the relevant vocabulary by analogy, as has often been done in the history of science – for example, in the analogical extension of hydrodynamics in the theory of electricity. So, to object to the ascription of psychological predicates to the brain on the grounds that in ordinary parlance such predicates are applicable only to the animal as a whole would be to
