1. Human beings, persons and parts

In his paper ‘Behind the Mereological Fallacy’ (this journal, 85 (2012), 329–52), Rom Harré challenges what Max Bennett and I have called ‘the mereological fallacy’. We argued that it makes no sense to ascribe psychological predicates such as ‘perceives’, ‘believes’, ‘thinks’, ‘hopes’, ‘wants’, ‘intends’, and so forth to the brain of an animal, since these are predicates that apply only to the animal as a whole, not to its parts. Harré argues that the fallacy is not a mereological one at all, but rather a Humean one of making an illicit transition from ‘is’ to ought', from factual considerations pertinent to physiology to normative ones pertinent to discourse about persons. So, for example, being angry is a reaction to what a person discerns as a moral fault in another's behaviour, and this normative discernment cannot intelligibly be derived from any description of the limbic system. Similarly, it is a moral fault to forget certain things (one's mother's birthday, for example), or to mislead someone by making overconfident memory claims, but one cannot ascribe moral faults to the hippocampus on the basis of its activities. So the roots of the error lie not in mereology, but in the Humean insistence that one cannot make a transition from ‘is’ to ‘ought’.

The reason the ascription of psychological attributes to the brain is not mereological, Harré avers, is that the brain is not a part of a person at all. So applying psychological predicates to the brain cannot be incoherent because it illicitly ascribes predicates of a whole to a part of that whole, for the brain is not a part of a person. The brain, he claims, is a part of a person's body, ‘and a person's body is not part of that person in the relevant sense’.Footnote ¹

Organs of human beings, according to Harré, are tools that a person uses to perform tasks. The hand is a tool we use to manipulate things, and the brain (or its parts) is a tool we use to perform psychological tasks. So, for example, we use the hippocampus and entorhinal corpus to remember. So, he claims, we can perfectly cogently say that the hippocampus is an organ for remembering, even though one cannot say that the hippocampus remembers.

I think that my friend and erstwhile teacher Rom Harré is mistaken. The error of ascribing psychological attributes to the brain is indeed mereological. It is true that we would not comfortably say that the brain is a part of a person – and there is a reason for that. Nevertheless, the brain is a part of the living human being, and a part of the corpse of a human being. Psychological predicates are predicable of living human beings (and many are predicable of other animals too), but they are not predicable of their brains. To predicate them of the brain is indeed a mereological fallacy. It is, I shall show, mistaken to assimilate parts of the body to tools. Furthermore, in the sense in which the eyes are organs of sight or the legs the organs of locomotion, the hippocampus cannot be said to be the organ for remembering. Nor can it be said to be the locus of remembering in the sense in which the stomach is the locus of a stomach ache. The answer to the question ‘Where and when did you remember that … ?’ is given by statements such as ‘When I was walking down the High Street’, or ‘While I was in the Library’ – not by ‘In my hippocampus, of course’.

Evidently the relationship between the concept of a person and that of a human being needs to be clarified before invoking the mereological fallacy and defending it. This is what I shall do here.

Harré correctly states that Max Bennett and I wrote ‘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 fallacy”.’Footnote ² Harré immediately states that this passage contains two presuppositions: first, that we clearly take the brain to be a part of a person, ‘since the predicates they are concerned with are psychological predicates, such as intending, being conscious, and so on, the application of which to animals is debatable’. Second, we presuppose that the normative implications of human psychological predicates can be taken through to the descriptions of lives of animals'. Harré rightly expresses qualms about saying that the brain is a part of a person in the same sense as that in which the liver is a part of the human body. John Searle raised the same worry in his response to us in the APA Meeting in New York in 2005.Footnote ³ We replied to this objection, but clearly the points need elaboration.Footnote ⁴

In Philosophical Foundations of Neuroscience, we stated that the mereological fallacy in neuroscience was the fallacy of ascribing psychological attributes to parts of an animal that can only intelligibly be ascribed to the animal as a whole. In the case of human beings, it is the fallacy of applying predicates that can only sensibly be applied to a human being to parts of a human being, such as the brain. The same principle was elaborated by Wittgenstein in 1953 in Investigations §281 (‘Only of a living human being and what resembles (behaves like) a living human being can one say: it has sensations, it sees; is blind; hears; is deaf; is conscious or unconscious’), and by G. H. Lewes in 1877 in The Physical Basis of Mind (‘it is the man and not the brain, that thinks; it is the organism as a whole and not one organ that feels and acts’.Footnote ⁵ We did not presuppose that the brain is a part of the person. The brain is a part of a human being in exactly the same sense in which the liver is part of the human being. One can also say, as Harré does, that the brain (and liver) are parts of the human body. The human body, in one sense, is the human being – the human organism. For human beings are animate bodies – living spatio-temporal continuants with a distinctive range of powers. However, one must not confuse and conflate the body (the living organism) that a human being is with the body (the somatic features) that a human being has.Footnote ⁶ Whatever is true of the body I have is true of me – if my body is sunburnt, I am sunburnt; if my body is healthy, I am (physically) healthy. But not everything that is true of me is true of the body I have – I may be proud or ashamed of my body, but my body cannot be proud or ashamed of its body; I may be in debt, but there is no such thing as my body's being in debt. However, everything true of the body – the living organism, the human being – that I am, is also true of me, since I am that (not: my) living body.

We did not ‘presuppose that the normative implications of human psychological predicates can be taken through to the descriptions of lives of animals’. Numerous psychological predicates have perfectly decent uses without any normative implications. Non-human animals feel pains, itches and tickles no less than we do. Many of them see and hear, smell and taste rather better than we do. They have appetites (as we do), and want things. They learn and come to know certain things, and in a rudimentary fashion they think and believe things (those things believing which is expressible within their behavioural repertoire). Although ascription of intentions to animals has been contested (by Stuart Hampshire and Anthony Kenny), the ascription of consciousness to animals is contestable today only in the sense in which the rotundity of the earth is contestable. The mereological fallacy that concerned us applies to non-human animals no less than to human beings. The brain of a dog does not see, any more than the brain of a cat is in pain or the brain of a rabbit afraid. These are predicates that can intelligibly be ascribed only to the animal as a whole. This is not an arbitrary whim of idiom. For it is the behaviour of the animal as a whole, in the circumstances of life, that licenses the application of such psychological predicates to it. Nothing a brain can do, no matter whether a human or a non-human brain, can satisfy the constitutive grounds (the criteria) for saying of it, that it sees or is blind, feels pain, wants to go for a walk or wants to be prime minister.

It is a moot question why we are reluctant to say that a part of a human being, such as the brain, is also a part of a person. After all, one has no qualms about saying that Jack has a brain, two legs and two arms, and so forth. One has no qualms about saying that people (persons?) have brains and limbs, and so forth. Similarly, Jack's brain is surely a part of Jack, no less than his legs and arms are. If Jack is so unfortunate as to be blown to smithereens, we may find his brains splattered all over the wall, and if we have to gather his parts for decent burial, we shall not omit his brains. Why then do we balk at saying that parts of the organism that is a person are also parts of the person? In particular, why are we loath to say that the brain is a part of a person, especially when we happily concur that Jack's brain is part of Jack? I conjecture that the explanation lies in the difference in categorial status between the formal concept of a person and the concept of a human being (much less marked, incidentally, between the concept of people and the concept of human beings). The concept of a human being is, inter alia, a biological one – a human being is an anthropoid ape, of the kind homo sapiens. The concept of human being also has obvious moral overtones, given that human beings qualify as persons.

The concept of a person is not a biological concept, but an ethical and otherwise normative one. Unlike the concept of a human being, it is not a substance concept. It is a status concept essential to our moral and legal thought. To be a person is to be a rational, language-using creature with powers of intellect and will, knowledge of good and evil, and possessed of free-will. That is why human beings, unlike the other anthropoid apes, qualify, qua species, for the status of persons. Babies are (immature, undeveloped, not yet responsible) persons, because it is part of their nature qua human beings to acquire those characteristics. Human beings who have lost the powers of reason through age, illness or injury are still persons precisely because they are damaged, impaired human beings – and must morally be treated as such. (A person in a vegetative state is not to be treated like a cabbage, but with the care due to a dreadfully injured human being.) Persons are bearers of rights and duties, they are answerable, responsible, for their deeds. They deserve the formal respect that is due to autonomous, free, beings. In so far as the (formal) concept of a person is invoked, we are moving in the domain of moral and legal status, not of corporeal characteristics (viz. ‘my/ your/ his/ her/ body’), nor of corporeality (in the sense in which human beings are (corporeal) organisms). That, I suspect, is why we are loath to link concepts of corporeal parts with the concept of a person, and yet feel no unease at characterizing the brain as being a part of any particular person one cares to mention. I originally offered the following analogy, in the hope that it might help to convey the point: London is a part of the United Kingdom. The United Kingdom is part of the European Union. But London is not a part of the European Union. That does not prevent London from being a part of the United Kingdom. So too, Jack's being a person does not prevent his brain being a part of him.

2. Organs and tools

Harré asserts that ‘The function of the brain in the life of a person is defined by the vernacular as an instrument or tool a person uses for carrying out certain tasks’.Footnote ⁷ This seems to me to be incorrect. Of course, we do say such things as ‘Use your brain!’ – but that, like ‘Use your mind!’, just means ‘Think!’. It is no more to be taken literally than the enjoinder ‘Consult your heart!’. After all, if someone were to reply ‘I'd happily do so, but what should I do with it?’, we should rightly think he had misunderstood an English idiom (like ‘My heart is broken!’ – ‘Then get some glue’).

We do have the notion of an organ, and the notion of the function of an organ. We also have the notion of an organ that we use in order to fulfil a function. These are not the same. Finally, we have the notion of tools and instruments that we make and use to fulfil certain functions. But organs are neither tools nor instruments, they are parts of an organism, and, contrary to what Harré (in an aberrant Cartesian moment) avers, the human organism (i.e. the human being) is not ‘a human machine’.Footnote ⁸ Machines do not have a good. They do not enjoy good health nor do they suffer from disease. They do not flourish and prosper. They do not have a life cycle of birth, maturation, reproduction and death. They suffer no pain nor do they enjoy pleasures. They are neither conscious nor unconscious. They are not free agents with two-way powers, and they are not responsible for their deeds.

The organs of an organism have functions. Some organs fulfil their functions independently of us: our stomach, liver, kidneys, spleen are not subject to voluntary control. One cannot do anything with these organs. Some organs are under partial control, such as the bladder or the lungs – but only up to a point. The use of our limbs, however, is subject to voluntary control. We use our hands to touch, to feel, to pick things up or move them, to manipulate things. We use our legs to walk and run, to step up and down, to kick or prod. We can use our head to nod assent or to shake dissent, and also to butt. The sense organs are firmly connected to the sense faculties. For it is by the use of our eyes that we can see, look at, detect or spot visibilia in our environment. We bring our eyes to the keyhole to see through it, or to the telescope to look through it. We shade them when the light is too strong. So too, we cock our ears to hear better, or go closer to the source of the sound. And so on.

It is, therefore, obvious that the brain is not an organ with which we can do anything, in the sense in which the limbs and the sense organs are. We have no voluntary or intentional control over the movement of our brain, because the brain cannot move and we cannot move it in order to do something with it. We cannot do anything without our brain, but it does not follow that we do anything with our brain. We cannot walk unless the motor centres of the brain are functioning normally, but that does not mean that we walk with our brain or that the brain is the organ for locomotion, as the legs are. We cannot see unless the ‘visual’ striate cortex is functioning normally, but for all that it is with our eyes that we see, not with our brain. We do not think with our brain, nor do we remember with our hippocampus.

Harré claims that the organs of the body in general, and the brain in particular, should be conceived as tools and instruments. The ulterior motive for this is to show that what he calls ‘the semantic fracture’ between neuroscience and psychology is not due to a part/whole category mistake, but rather to failure to keep a clear line between the factual and the normative. The descriptions of tools, Harré contends, is independent of the normative characterization of the tasks they are used to perform. Are organs of a human being (or any other animal) not kinds of tools or instruments? There are analogies. First, we use our limbs and our sense organs to do things, just as we use tools such as screwdrivers. Secondly, we use instruments, such as spectacles or hearing aids, to improve our perceptual abilities in the case of defects in our sense organs, or to extend our perceptual acuity and range (in the case of microscope or telescope). So it is tempting to think that the organs, including the brain and its parts, are akin to instruments we use.

This temptation should be resisted. Organs are not designed, instruments are. Organs are parts of substances, but not substances themselves; instruments, by contrast, are substances.Footnote ⁹ Organs are internally related to the beneficial, to the good of the animal whose organs they are. Their proper functioning contributes to the animal's successful engagement in activities characteristic of its kind. The function of artefacts and hence too of instruments is related to their usefulness when employed for the purpose or purposes for which they were made. Good organs, including good organs of perception, are healthy organs that perform their function optimally. The goodness of organs in general and of organs of perception in particular is privative. Good eyes are eyes that are not deformed, diseased, or defective – they function well. Optimal functioning is tested by reference to standards of normalcy of the species. Good instruments, by contrast, are not normally-functioning instruments. A good knife not one that is all right, and that there is nothing wrong with one's telescope does not imply that it is a good telescope. The goodness of instruments, unlike the goodness of perceptual organs, is not privative. A good instrument of a given kind is one that can be used (by someone with the requisite skill) to serve well, or even exceptionally well, the purpose for which they were designed.Footnote ¹⁰ We manipulate instruments and tools, but we do not manipulate our hands when we use them to manipulate instruments, and there is no such thing as manipulating our brain. We use, and can misuse instruments. But although we can abuse our organs, as when alcoholics abuse their liver, and as when people become addicted to brain-damaging narcotics, there is no such thing as misusing our brain, our stomach or our liver. To drill a hole right through a wall, instead of in the wall, is to misuse the drill. To miscalculate, misunderstand or misremember is not to misuse one's brain, and to have a couple too many is not to misuse one's liver.

Ascribing psychological attributes to the brain of animals in general and of human beings in particular is a mereological error (that leads to fallacies). It ascribes predicates that can intelligibly be ascribed only to the animal as a whole to its parts. The reason for that is that only the animal as a whole can satisfy the constitutive behavioural grounds or criteria for the ascription of such psychological predicates. This has nothing to do with Humean qualms concerning fact and norm, even though it is perfectly true that one cannot hold one's organs morally responsible for one's deeds. Neither the brain nor any other organs of the body are tools or instruments. Neither the brain nor its parts are organs for exercising psychological powers in the sense in which eyes are organs for seeing and ears are organs for hearing.