In his searching criticismFootnote ¹ of my proposal to shift the point of breakdown of ‘neuroscience as psychology’ from the mereological fallacy to the fallacy of slipping into an ‘ought’ from an ‘is’, my old and valued friend and colleague Peter Hacker defends the force of the mereological fallacy in the context of what I take to be human beings qua members of the species homo sapiens. I believe that this leaves us with two possibilities for managing research in psychology: the study of certain aspects of the lives of members of the species homo sapiens qua higher animal and the study of members of the homo sapiens qua person. Hacker and I are concerned to explore the nature of the relation between the presentation of our knowledge of biological aspects of being a human being and features of the cultural-discursive practices with which people manage their lives and which are the topic of one important branch of scientific psychology, the cultural-instrumental-historical psychology initiated by Lev Vygtosky.Footnote ² The above distinction in ways of apprehending human beings seems to be clearly foreshadowed in the writings of Immanuel Kant, particularly in his Metaphysics of Morals.Footnote ³

We agree that there is a semantic fracture in the pattern of uses of the key words that are used in describing members of the species in general. My focus in shifting the place of this semantic fracture for the purposes of a defence of psychology from the mereological fallacy to the ‘is-ought’ fallacy, famously emphasised by David Hume,Footnote ⁴ is to see the flaw in hegemonic neuroscience in the context of cultural-discursive practices and the uses of what purport to be the same key words in neuropsychology. We find ‘depression’ and ‘serotonin reuptake inhibitor’ in the same sentence in a description of the state of the very same human being. Yet not so long ago, but before the rise of synaptic chemistry, people distinguished between candida bilis and atra bilis, as distinctive ways of being gloomy with respect to the cultural patterns of the day.Footnote ⁵ So far as I know this distinction has not lived on into neurochemistry. So ‘depression’ as a feature of how some people feel is a more complex human affair than a matter of correlations with reactions among the molecules of synaptic chemistry.

In their comprehensive study of the philosophical aspects of neuroscience Bennett and HackerFootnote ⁶ illustrate their argument with a plethora of examples of fallacious uses of predicates appropriate to persons when ascribed to their bodily parts.Footnote ⁷ This discussion is important in that it bears upon the attempts to promote neuroscience as the scientific version of psychology, the study of human beings thinking, feeling, acting and perceiving. My rejoinder to Hacker's comments is to highlight the distinction between human being qua higher animal and human being qua person, and to defend the autonomy of cultural-discursive psychology as a scientific discipline devoted to understanding human beings qua persons by picking up a different philosophical error characteristic of the proceedings of entrepreneurial neuroscience from the mereological fallacy emphasised by Bennett and Hacker.

Using the concept of ‘human being’ as a device for delineating the field in which psychology is to be pursued as a cluster of scientific research programs leaves much indeterminate. The trouble with ‘human being’ is that it might be located in an empirical discourse such as genetics or synaptic chemistry or the procedures of mapping the brain regions active in human beings who are carrying out various tasks, or it might be located in a normative discourse such as that of a war crimes tribunal, or the safety instructions in an engineering apprentice training scheme, or the distribution of household tasks among reluctant adolescents, or hoping for a Gold medal in an athletic context, or remembering what seems to be an undoubted fact, or how to maintain a cognitive skill such as playing a musical instrument, and so on, for all of the affairs of humanity.

I am quite ready to accept Bennett and Hacker'sFootnote ⁸ identification of the mereological fallacy in analysing the relation between a human being qua member of the higher animal species homo sapiens and that being's body as part of the human being as a whole.Footnote ⁹ Identifying the mereological fallacy in this context blocks too ready a transference of predicates from discourses apropos of the whole human being qua higher animal to the organic processes that go on in the body of that human being. This leaves us at the level of psychiatry as chemotherapy, synaptic chemistry of the relevant neurotransmitters as the material grounds of various emotional experiences, some aspects of sport science and ethology à la Desmond Morris.Footnote ¹⁰ Hacker reminds us that many animals, including higher animals like ourselves, live in life-worlds with discernible moral characteristics that are not just the products of anthropomorphism. For a psychology that will treat of these beings, as persons, I maintain that the ‘is-ought’ fracture appears in the semantic fields of words recruited from the vernacular to the purposes of neuropsychology. ‘Anger’ is a morally defensible response to a justified harm, while ‘flush of adrenalin’ is chemistry.

However when we turn to the predicates that are the stock-in-trade of cultural-discursive psychology as they appear in discourses that purport to be about the relation between a human being qua person and the neuroscience set aside by the mereological argument, that argument will not catch hold because a person has no parts, as Hacker agrees. Nevertheless, it is even more important for the health of cultural-discursive psychology as an independent discipline that unqualified wholesale transfers of predicates from their use for a person to an application to that person's body or some of the parts thereof should be blocked. There might be instances in which a special case could be made for the non-toxic character of such a transfer, but it would need to be made for each such putative exception, for example the search for the biological basis of chronic fatigue syndrome in the face of accusations of malingering.

Our debate is only superficially about which fallacy to choose as the basis of a reprimand to too ambitious neuroscientists. Either the mereological fallacy or the ‘is’/‘ought’ fallacy would block the hegemonic bid by certain neuroscientists to be reconstructing the core of a scientific psychology, illustrated in a wide range of cases by Bennett & Hacker.Footnote ¹¹ Rather our debate is about how to qualify ‘human being’ for the purposes of defining the field of such a psychology. The point of disagreement and the focus of the debate appears clearly in Hacker's remark that ‘psychological predicates are predicates that apply essentially to the whole living animal, not to its parts’.Footnote ¹² Cultural-discursive psychology, exemplified in the writings of Lev Vygotsky,Footnote ¹³ Jerome BrunerFootnote ¹⁴ and others is concerned with predicates that apply to the human being, but not qua higher animal, the whole living animal, rather to the human being qua person, such as ‘reminisces with old friends’, ‘chooses from the menu’, ‘hopes for a fine afternoon’, ‘finds the prisoner “Guilty”’ and so on and so on. What makes these predicates special is that their uses are embedded in normative systems characteristic of the local culture,Footnote ¹⁵ and what they mean case by case depends in part on the details of that culture. Predicates that apply to human being qua member of the animal species homo sapiens are of peripheral interest for cultural-discursive psychology and are relevant only in so far as they loosely limit the scope of the attribution of psychological predicates as they appear in the phenomena that psychologists study. From my reading of the extensive examples in Philosophical Foundations of Neuroscience,Footnote ¹⁶ it seems to me that the authors see the topics that concern cultural-discursive psychologists as the proper field for the methods of analytical philosophy. Of course, Bruner et al would agree but would look to empirical studies of the ways these key words are used in the management of life as a fit topic for an alternative scientific psychology.

If I am to succeed in distinguishing studies of human beings qua members of a higher animal species and human beings qua persons I need to elaborate the concept of ‘person’ further, as it appears in the foundations of these studies. This notion informs the thought behind the original paper in this debate.Footnote ¹⁷ Much more would need to be said apropos of Hacker's assertion that ‘The concept of a person is not a substance concept, as is the concept of a human being’Footnote ¹⁸ followed shortly thereafter by the further comment that ‘… the concept of a person qualifies a substance concept of an animal of such and such a kind … identified by its powers and capacities …’Footnote ¹⁹ Does that allow ‘person’ to refer to a kind of animal? But what kind? Psychologists aiming at a working hybrid discipline that gives due place to biological and cultural studies assume that there is a ubiquitous material world into which the barely prepared human animal is ‘thrown’, and one or other local moral worlds which have been constructed by others in which that being is transformed into a person.

I can only attempt a brief sketch of what ‘person’ means in cultural-discursive psychology.Footnote ²⁰ As the concept is used in that version of psychology, a person is a singularity having a unique trajectory in space-time. A person is embedded in a world of moral relations to other persons, is held responsible for his or her actions and in the default condition is morally protected. Thus ‘person’ is, inter alia, a ‘forensic’ concepts as Hacker reminds us, but a great deal more. As BrinkmannFootnote ²¹ and others have emphasised, psychology is or ought to be a ‘moral science’ – that is concerned with research into implicit and explicit norms and rules for the conduct of life – moral, (being selfless) prudential (eating right) and practical (holding a saw the correct way). This is made explicit in the research programs of ‘positioning theory’ – that is studies of how rights and duties to say and do and refrain from saying and doing certain things, are distributed moment by moment among a group of people. In some contexts personal embodiment is a relevant consideration but by no means in all.

These features of the concept of ‘person’ are displayed in the indexical functions of the first person ‘I’. Using it to introduce a speech-act indexes the content of the act with the spatial location of the speaker (like ‘here’ does) and the illocutionary force of a speech act introduced by ‘I’ with the standing of the speaker in the local moral order (reliable, dishonest, casual. self-serving and so on). Correct application of the conventions of first-person grammar means that local knowledge of the relevant moral order and the speaker's place in it is necessary to understand what someone is saying and doing. Grooming on the Internet as a discursive practice in which the first person singular occurs is spatio-temporally indeterminate but morally unforgiveable.

The contrast in research programmes to which my article was directed was not that between neuroscience and mainstream psychology (a dying art) but between neuroscience and cultural-discursive psychology. This leads to the second phase of the debate between us. What is the most fruitful trope with which to elaborate the meaning of ‘person’ in the cultural-discursive paradigm with respect to the fact that, in the circumstances in which research into some phenomenon using cultural-discursive psychology is often undertaken, it is relevant that each person is embodied?

If I am to defend my way of setting aside part/whole as the best interpretation of the human being qua person as the source of the incoherence of reductive neuroscience as a general psychology I must propose some more useful tropes with which to shape research programs in which embodiment is a relevant feature of the cultural-discursive situation. An alternative to the part/whole metaphor that recurs frequently in psychiatric and medical contexts, and risks commission of the mereological fallacy, is something that could be expressed in the distinction between ‘person’ and ‘site for a person’. When Michael Sciavo defended his decision to terminate the life support for his ‘brain dead’ wife, Teri Sciavo, despite the protests of her family and the disapproval of the President of the United States, his argument amounted to the claim that there was no person there. The body was uninhabited by a person, and only persons are fully morally protected.Footnote ²² This presupposes that Teri Sciavo's body was perhaps a feature of the original establishment of a person Vygotsky-wise, but the skills and abilities that were distinctive of personhood had ceased to be displayed by that being. Using the body-as-site-for-person trope the person had disappeared. Perhaps the relation ‘site of’ captures the presumed relation in this history somewhat better than any other. A site and the building erected on it are strongly related, for example they have the same street address, but the site is not part of the building. Demolition of the building can occur independently of the integrity of the site. Back to the choice of trope!

Another metaphor for managing research programs in cultural-discursive psychology in which embodiment is an important consideration is that of person as agent undertaking a task and body and its parts as a tool kit for accomplishing some of them. Peter Hacker 's criticism of the use of the ‘task-tool’ metaphor as a way of linking the discourses of human being qua higher animal with human being qua person was based on a thorough examination of the uses of ‘tool’ in a variety of contexts. My defence of the ‘task-tool’ metaphor should not be seen in the context of the surview of a field of family resemblances among the uses of ‘tool’. Rather it should be tested in the context of the problem of devising research programs in which neuroscience and cultural-discursive psychology are both used to explore the nature of mental disturbances, as defined by the current norms of society that appear in the activities of people going about their everyday lives. An elderly person no longer recognises her relatives. A man claims to hear voices urging him to carry out socially and morally unacceptable actions. The psychiatrist proposes the hypothesis that there is something abnormal about the brains of such people. The lawnmower cuts an uneven swathe – the gardener proposes that the blade is wrongly positioned. Youthful remembering, acceptable modes of action and tidy lawn mowing are dependent on the right working of the equipment where ‘rightness’ is determined by the propriety of the activity being performed in the relevant form of life. The delineating of a task and the standards that must be met for it to be well done in a certain cultural-historical context are independent of neuroscience. While failures to perform ‘correctly’ are sometimes due to ignorance or misunderstanding or wilful rejection of the local normative framework, they are sometimes due to a defect in the ‘machinery’, some aspect or part of person's body qua instrument by means of which the proper task is to be carried out. Adopting this trope is not a contribution to the ‘grammar’ of ‘tool’ but to a way of shaping hybrid research projects, such as those that have revealed the role of the chemical serotonin re-uptake inhibitor in the management of the socially and the culturally defined form that depression currently takes. Genetics tells us of the origins of the neuro-machinery while cultural-discursive psychology tells us how people of this or that tribe ‘use’ it.Footnote ²³ Robin Dunbar is fond of the correlation between the genetic determination of the optimum tribal population size and the number of people involved in the practice of sending Christmas cards! Mutatis mutandis, when tasks are accomplished correctly according to local standards the mechanism that was defective in the sufferers from psychopathologies may be taken to be functioning ‘correctly’. The metaphor of ‘use’ goes along with the basic trope of ‘tool and task’. The history of engineering tells of the origin of the lawnmower, but it is to garden designers we look for the ways in which it should be used. After all, one can use a saw as a musical instrument. The involvement of the local culture is evident in the use of ‘lawn’ to qualify ‘mower’. A mower will cut grass but a lawn mower is capable cutting grass according to the local standards of what is a good lawn – the White House lawn is left much longer than the Buckingham Palace lawn.

As a final remark apropos of Wittgenstein's reflections on embodiment, it is worth returning to the famous paragraph in the Philosophical Investigations §281, where he lists the distinguishing psychological features of human beings.Footnote ²⁴ The list comprises the following attributes: ‘Only of a human being and what resembles a human being (behaves like a living human being)Footnote ²⁵ can we say it has sensations, it sees, is blind, hears, is deaf, is conscious or unconscious’. Then it ends. Why doesn't it continue with hoping, remembering, intending, willing and so on, topics that are discussed at large by Wittgenstein, not only in the Philosophical Investigations, but in many other places? The psychological phenomena discussed in these topics are intrinsically normative. The list Wittgenstein provides is just the attributes that distinguish human beings qua higher animals and which are shared with our primate cousins and some domestic animals. But it falls short of those that distinguish persons from other primates. Is it that the study of such phenomena such as hoping, being angry with someone, failing to attend to what one should have, making plans for a trip, and so on are the preserve of analytical philosophy? Cultural-discursive psychology takes its inspiration from what is passed over in silence in §281 in making its claim to be as much a scientific discipline, properly understood, as neuroscience, though with distinctive methods, and with extensive use of predicates the meaning of which has an ineliminable moral or normative aspect. Here we have the nub of this discussion: there can be no doubt that the accusation of the commission of a mereological fallacy or fallacies is fatal to the use of psychological predicates the meaning of which is determined by their use in the context of the lives of higher animals in any putative neuroscience. However, the predicates that appear in cultural-discursive psychology are just those that do not appear in the list in §281. Their target of attribution is a person or persons. And we all agree that persons have no parts. So neuroscience which purports to ascribe say, hoping, to some part of the brain of the person who is properly said to be hoping (and its use covers a wide field of family resemblances) cannot be committing the mereological fallacy. The relation of ‘brain’ to ‘person’ is not that of part to whole, but perhaps tool to performer of a task. The fallacy, as I have argued, is none other that the old ‘is/ought’ fallacy identified by David Hume.