5: We are constructs ourselves
Gerhard Roth on the creation of reality in the brain, on a reality independent from human consciousness, and on the relationship between neurobiology and philosophy
Gerhard Roth (b . 1942) studied philosophy, German philology, and musicology, obtained doctorates in philosophy and in zoology. Since 1976, he has been professor of behavioural physiology at the University of Bremen, since 1997 also founding president of the Hanse-Wissenschaftskolleg at Delmenhorst near Bremen. This College is intended to be a place for the cross-border debate of questions of cognitive science, and a forum for the interdisciplinary exchange between the social and the natural sciences.
Roth’s primary research interest - he is, at present, engaged mainly in brain research - is the encounter of a barely conceivable kind: the encounter between matter and mind, nature and cognition, in the brain of an adult human, an organ weighing about 1300 grams and containing between 100,000 million and a billion neurons. It is still something of a puzzle how the material substance of the neurons affects the immaterial substance of the mind (and vice versa). It is well known that the act of thinking is accompanied by a concert of firing neurons, and that it cannot, therefore, take place without a base that is located in the brain; but as yet, a full understanding of the mechanisms of this interaction has not been achieved.
The basic project, whose contours have - despite the many unsolved problems - become discernible, is committed to unravelling ultimate mysteries that do not repose in remote regions of space or in an external universe but deep within human beings. Their solution is now expected to be delivered by biology. Geneticists are decoding the human genome; neurobiologists are working on a naturalist explanation of cognition and consciousness. Therefore, Roth - director at the Institute of Brain Research at the University of Bremen - calls cognitive neurobiology, with reference to the German terminological tradition, a geisteswissenschaft, “of a special kind”. It investigates how perceptions and mental states take place. It attempts to tackle the key question of the relation between res extensa (matter) and res cogitans (mind; spirit; consciousness) that has remained virulent since René Descartes first formulated it in the 17th century. It describes how a human brain produces the image of an external world with all its riches of sounds, smells, colours and shapes. The link between this research programme as designed by Roth and the cognitive quest of constructivism is immediately apparent: the purpose of cognitive neurobiology is to discover the rules of reality construction as they operate in an organism’s brain.
The unknowability of the absolute
Poerksen: It is commonly assumed that perception is a representation of reality: the knowing mind, it is claimed, mirrors something that is external to it. You insist, however, that our organs of perception and our brains are essentially incapable of apprehending the world in its primordial, its real, gestalt. What are the arguments supporting this claim?
Roth: The first argument is that only very few events in the world can stimulate the sense organs and affect them at all. What is perceived is, therefore, never a representation of what exists but always a selection. The most ancient sense organs are probably the chemoreceptors; they are a particularly archaic equipment for the perception of the world. For organisms living in a watery environment, it is important to distinguish between food, enemies, and mating partners, to maintain equilibrium and orientation, but certainly unnecessary to know what the properties of the world as such might be. Neither are the human sense organs geared towards the exact apprehension of reality; they serve to identify happenings in the environment that are relevant for our survival. Only when the problems of survival are solved, can we start the philosophical discussion as to whether anything exists at all, or whether something exists independently from our biological needs.
Poerksen: Now we could argue, however, that sense organs have - relative to the intensity and the duration of the survival training during the course of evolution - become ever better adapted to the external structures of the real world. The more successful an organism’s activities in its environment are, it is claimed, for instance, by the proponents of evolutionary epistemology, the greater the precision of its representation of an external world will be.
Roth: It is an interesting fact that most of the oldest organisms that have survived and reproduced successfully for a very long time - bacteria, unicellular and simple multicellular organisms - do not possess anything resembling a brain. The view of evolutionary epistemologists is wrong for one basic reason: successful survival, in the majority of cases, is simply not dependent on complex sense organs and a complex nervous system. Often quite primitive perceptual equipment is sufficient. However, as soon as the organisms with simple structures have occupied all the niches, brains that are more complex develop because, due to the competitive struggle, animals are pushed into environments that are more difficult to cope with: the enemies camouflage themselves; it is more laborious to find food and to recognise prey; and social and sexual relations are proportionately more complicated.
Poerksen: So the brain was originally an organ of flight and a mode of dodging in order to colonise other niches.
Roth: We might say so, indeed, when examining the course of evolution with all due calm and restraint. The increase in the complexity of sense organs and brains does not imply, however, that organisms are able to apprehend the world with a higher degree of ontic adequacy: the perception of bats, working with low-band echolocation, is tuned to fluttering insects. These animals are not truth seekers; all they want is to catch their prey in complete darkness.
Poerksen: Are you suggesting that human perception is no better or worse than a bat’s vision in darkness? Or do our images of reality indeed come closer to the absolute reality of what is given?
Roth: That might certainly be the case unless we are under the impression of a gigantic delusion - which cannot be excluded, of course. The brains of our primate relatives are not designed to attain absolutely valid knowledge of the world; we humans, however, unlike most other animals, possess the capability of looking ahead, the fundamental ability of presaging what will happen next. Such predictive competence sets us apart from bats or macaques and does indeed imply that our grasp of the world is of a more objective kind. The potential increase of objective knowledge would then be no more than a sort of by-product of the peculiar evolution of our brains.
Poerksen: How would you check a gradual approximation of reality?
Roth: This will have to remain a hypothesis, a reasonable assumption, no more. However, we can definitely claim within the confines of our experiential reality that it would be an enormous advantage for macaques to be able to discern what their tribal companions were planning to do within the next few hours. Macaques, however, are not very interested in the thoughts of others (unlike chimpanzees and humans); they may not even possess a theory of mind: they may not be able to take another’s point of view so as to predict their activities. Are the perceptions of macaques less objective? The answer to this question must remain a matter of taste, which is not amenable to a final assessment.
Poerksen: The question of taste, then: are you in favour of assuming that human perception is increasingly getting closer to ontic reality?
Roth: One of my beliefs is that we are indeed able - within given constraints on cognition - to assess different or even contradictory theories as more or less valid. An astronomer’s prediction of the position of a planet is either correct or incorrect; we can, therefore, say with some justification that the correct computation is a more adequate representation of the world of the planets than other models that lead to incorrect predictions. That is why I am not a radical constructivist viewing science and magic as equally valid conceptions of reality. I insist on a precise distinction between different levels of plausibility. Science is on a different plane from magic; its predictions are more successful.
Poerksen: Reviewing the first few moves of our conversation, I notice a constant oscillation between two positions. You emphasise, on the one hand, that there can be no doubt that we are cognitively constrained. On the other hand, you appear to imply that certain perceptions are more valid than others in an absolute sense. It seems to me that these two positions contradict each other.
The brain and its reality
Roth: The contradiction arises only if one fails to make accurate distinctions, in one’s epistemological worldview, between metaphysical statements about the existence of the objective world, and differentially reasonable assumptions. I cannot, in principle, say anything about a world that is independent from my mind. Everything I am capable of saying is dependent on my consciousness and my unconscious. An “objective statement” in this context would indeed be a contradiction in terms. Nevertheless, it seems possible to increase the internal consistency of assertions in our worlds of experience and science by allowing ourselves to be guided not just by intuitions but by strictly regulated procedures of scientific investigation. In this way, we can reach an extremely practicable system of assumptions, which it would be simply absurd and unreasonable to call into question. When someone tells me that it is raining, I can easily check that by going outside and observing whether the sun is shining, whether there is only a drizzle, or whether it is pouring. I may ask other people to corroborate my individual perception intersubjectively in order to increase its internal consistency and coherence and to exclude possible sensory delusions. But this phase of doubt, although reasonable and significant, must terminate at some point.
Poerksen: In your books, you present the thesis that the brain, which constructs its own world, belongs itself to a world independent from the human mind; the brain, you claim, is part of the sphere of absolute and unconditional reality. How are we to understand that?
Roth: The thesis is necessary because the world of science does not admit logically contradictory statements. For neurophysiology, the basic assumption is, of course, that everything I perceive is constructed by a brain that also constructs me, my own self. To render such an assumption plausible I must presuppose the real existence of a brain that produces this experience. Although there can be no final proof, it seems most reasonable and plausible to me to posit the existence of an external world independent from the human mind, which contains, amongst other things, real brains. Extending radical doubt to the brain and its existence in reality would entangle me in contradictions.
Poerksen: I do not see why. I can argue with wonderful consistency: as a neurobiologist I formulate whatever I say within given biological and cultural cognitive constraints; the assumption of an external world that is independent from these constraints is unnecessary. I would in fact propose a contrary claim: the dualist division between a real brain and a tenuous reality constructed by that brain leads to a contradiction. My thesis is: this dualism is essentially a clandestine realism.
Roth: Let us attack the problem as clearly and logically as possible. The claim in question is: B is produced by A and depends on A; it is, however, uncertain that A exists. If I do not know that A exists, I cannot know whether B exists. Consequently, the existence of both A and B is uncertain. If I take as my point of departure my own conscious experience and the feeling and thinking instance of my self, which it would be absurd to doubt because there is no alternative, then there must also be a brain that produced that experience and the perceived phenomenal world, in the first place. This reality-producing system - namely, the brain - cannot, for logical reasons, be part of the constructed experiential world that I perceive: the author of a play cannot be part of it, except as an actor; the painter of a picture cannot be part of it, except as one of its components.
Poerksen: A consistent formulation from a constructivist perspective might look like this: we are all drifting around in a dark universe, we draw up certain projections of reality in places, we describe - conditioned by education and socialisation - a brain and its reality, and at some stage we stop. There can be no point at which I could possibly extricate myself from my world of observer-dependent descriptions and make assertions that would factually refer to an absolutely valid reality and a brain in itself.
Roth: But that is not the problem at all. The problem is much rather that even constructivists are compelled to make certain logical assumptions to make their assertions and pronouncements meaningful. Constructivists cannot deny the existence of an observer and of observations; they must presuppose the existence of their minds.
Poerksen: Who is this observer? Who is this consciously experiencing self?
Roth: Ultimately, of course, nothing but a construct, too. There is no self that is sitting somewhere in the brain watching the images of an external world on a screen, and trying hard to puzzle out whether these images match an unintelligible world or not. Such scenarios correspond precisely to the epistemology of subjective idealism held by many constructivists. The question how such a self constructs its own world seems totally absurd to me; this kind of view must be radically abandoned. There is no self that constructs the world and watches images in its brain; nothing exists except constructs by brains. We are constructs ourselves. I am forced to formulate: I exist, but as a state of sensation and experience, I am a construct, I am an image, only a virtual actor, a virtual world of experience for trying and testing possibilities of action, for planning a future. Such a virtual centre we call a self; it is extremely beneficial for survival in complex and strongly fluctuating environments.
I think, therefore I am
Poerksen: What do you then mean by asserting that the mind and a self nevertheless exist? What does existence mean?
Roth: To exist simply means: I exist, think, and sense myself here and now! Apart from that, the concept of existence cannot be defined with precision from a scientific point of view (just remember the oddities of quantum physics). To deny the reality of one’s thinking and, consequently, of one’s existence would be bizarre, as was already clear to René Descartes. The cultivation of total doubt would render any further investigation of mind and brain pointless and logically incoherent. However, if my own thinking is no longer in doubt I can take the second logical step and seek an answer to such questions as: where do I come from, who created me and my conscious experience, who produced me? If I do not take the view of the solipsist that I have created myself, then I must have been produced by something else. The answer of the constructivist and neurobiologist Gerhard Roth is: there is a system called the brain; it has produced me and caused my existence; and if I exist in my world of experience then that brain must exist, the brain that I can describe with neurobiological models. And then the next logical step is: if the neurobiological assumptions are correct and internally consistent, if the brain is actually present in my body, then an environment must also be assumed, with which I can interact and by which I am nourished. So there must be an environment for purely logical reasons.
Poerksen: The intellectual approach and the figure of argument you are employing are, consequently, anchored in the Cartesian “I think, therefore I am”, and you then proceed to generalise this primary and indisputable existential assumption step by step and finally extend it to cover both the brain and the environment.
Roth: You could put it that way. The final remaining question is whether the assumption of a mind-independent world is inconsistent with this line of reasoning. My answer is: no, it is not. On the contrary, it is highly plausible to assume that my self is identical with a state of my brain, that this brain is an integral part of my body, that my body belongs to an organism, and that this organism is situated in an environment that is independent from my mind. Such a line of reasoning carefully evades the question whether my assertions are objectively correct. It rests entirely on logical inference, and not on metaphysical speculation.
Poerksen: I cannot follow the last argumentative step in the chain of your generalisation of existential assumptions. I cannot see how you finally manage to derive the claim that a mind-independent reality exists.
Roth: Well, in that case you fail to understand one of the central assumptions of both the moderate and the radical variants of constructivism: even the radical constructivist admits that it would be absurd to cast doubt on the view that there is a world existing independently from my thinking and the existence of my mind.
Poerksen: For me, utterances of this sort betray the hidden metaphysics of constructivism: something is claimed about which - according to accepted premises - nothing can be said, and then fundamentally untestable existential assertions are derived. The assumption of an unquestionably existent external world certainly sounds more reasonable and more welcoming and will certainly boost its public acceptance. All the same, against the background of the basic contentions, the assumption seems to me mere speculation.
Roth: Your criticism is fallacious. Although I may start with the admission that my claims concerning a mind-independent world are in no way absolutely certain, nobody can prevent me from speculating about the potential existence of that world and to try to develop my own ideas about it in as rational a way as possible. Let us assume that there is a mind-independent world to which we ascribe specific properties. I can then ponder what might follow from those assumed properties. As a scientist, I can make certain predictions; and I may in the end - should the predictions be confirmed - arrive at an intersubjectively plausible model of that world, which can continually be improved. Let me repeat that the only possibility I see is the optimisation of this internal consistency. Scientists, however carefully they may proceed, can do no more than to perceive observations and research data and relate them to each other. Their observations can only be checked by means of other observations; they can never extricate themselves from the world of human perception and thinking. Saying this and asserting it explicitly beforehand, entails that I cannot be classified as an objectivist and a metaphysicist.
Poerksen: Nonetheless, whoever describes an unbridgeable frontier of cognition and an eternally hidden absolute, will unavoidably inspire attempts to tackle the question of what might lurk behind that frontier. They will arouse curiosity and interest and stimulate the exploration of the unknown. Perhaps metaphysics and mysticism will regain a place in the wake of such constructivist inspiration.
Roth: It is indeed my impression that some constructivists are mystics straight and simple. Their glorification of the unknowable is the reason for my reserve and also, of course, for various disputes. I approach these questions in a much more innocent way, and I am amazed to observe over and over again how even sane people can perceive the so-called one and only world in so many different ways, immune to any enlightenment, and how they construct their own realities in their brains.
The language of the neurons
Poerksen: How does this take place? Perhaps the best approach would be the demonstration of a very simple situation: some external stimulus is registered, and suddenly we perceive something, we hear a melody, feel pain, or see a picture. How does our brain construct such sensations and impressions?
Roth: Only a tiny fraction of the totality of external stimuli reaches us, and only a portion of that fraction is transformed into electric activity, the uniform code of the nervous system, and into chemical messengers, so-called transmitters. The brain has produced the reality we experience and live in. The brain, however, has no direct contact with the environment, and therefore the transition from the physical and chemical environment is a radical break. Everything we see, hear, smell, think, and feel is the result of a gigantic construction performance of the brain.
Poerksen: In precise detail: What happens when we both see a picture?
Roth: Seeing a picture has many dimensions. What reaches the brain from the photoreceptors in the eye, the rods and cones, via a number of intermediate processors, are, however, only two kinds of information relating to the wavelength and the intensity of a point of light. From the different wavelengths, the brain later computes the colour of the picture; the light intensity is the source of the distinction between bright and dark areas. The impression of spatial distribution, gestalt, form, and depth is derived from the activities of many different receptors by the brain. The consequence is that there is no colour, no form, no space, no movement, no depth, and definitely no meaning, at the level of the retina.
Poerksen: You say: what excites my sense organs is not coded there in its specific physical or chemical properties but reaches the brain exclusively in the form of electric impulses and neurotransmitters. This means, however, that the motley, multi-coloured, and many-shaded world in which we live must somehow re-emerge from the indistinguishable grey of the uniform neuronal code.
Roth: It is the highly skilled task of the theory of perception to explain this. The first father of modern physiology, Johannes Müller, believed that relating the different sensory qualities and modalities to various substances that are transmitted through the nerves might solve the problem of the infinite multiversity of perception. He postulated substances of vision, hearing, smell, and taste, which on external stimulation creep from the eyes, the ears, the nose etc. through the neural tubes to the brain. The brain then assesses the incoming substances and decides: aha, a visual impression, a smell, or a taste!
Poerksen: This would actually mean that the world’s infinite nuances are already integrated into the receptive apparatus of human beings.
Roth: This view inspired Johannes Müller to formulate the famous law of the specificity of sensory energy. His pupil Hermann von Helmholtz, who discovered together with his colleagues that all sensory stimulation was transformed into relatively uniform nervous impulses, refuted it just over a hundred years ago. This is the principle of the neutrality of the neuronal code. Its acceptance renders the multiplicity of perceptual contents very mysterious. Sensory physiology, the growing sceptic Hermann von Helmholtz asserted, would never be able to explain the different experiential qualities. However, this is an error. Our sensory apparatus, it is true, converts all the different stimuli - electromagnetic waves, odorous molecules, sound waves, mechanical deformations - into more or less identical neuronal excitations. When I record such excitations in my laboratory, I cannot tell whether the registered nerve impulse is related to smell or taste, feeling or thinking. But the brain can do that. How does it manage to create our infinitely varied experiential world from the uniform pulp of neuronal events? The solution of the puzzle: it essentially depends on the location of the impulse in the brain. If there is an impulse in the visual cortex, a visual impression will arise independently from where the excitation comes from, whether it originates in a natural input from the retina or in an electric stimulation. If the same impulse, however, reaches the auditory cortex, an auditory sensation will arise, if it arrives in the somatosensory cortex, the brain will register an impression of touch. There are comparable special areas in the brain for qualities like colour and form.
Poerksen: The activation of a particular spot causes a specific impression to arise; suddenly we hear and feel.
Roth: Exactly. The optic nerve terminates in a particular section of the brain, which is different from the terminal areas of the auditory nerves. If there were confusion, we could hear lightning and see thunder for a while, until the brain had registered the mix-up through behavioural control and rewired itself. The specificity of an impulse results, as we know today, from the topology of the brain: different locations of activity define the modality, the quality and the intensity of a stimulus.
Poerksen: How does this explanation fit the observation that we cannot perceive stimuli separately, that we cannot experience colour, form, and movement independently? There ought to be a further mechanism in the brain that integrates the diverse excitations into the final comprehensive impression, which might, for instance, mean: this is a big red ball flying through the air.
Roth: There is indeed such a mechanism but before it can be activated, the different sensory stimuli must first be constituted independently from each other. This is necessarily so because after the different kinds of information have been pooled they cannot be recovered again. Whenever we see something we do not only perceive the total image but we can always pick out singular impressions and details, describe particularities like colour or form etc. This means that the possibility of recognising both details of arbitrary calibre and the overall image must be available in parallel. Here, too, the brain works with distributed and anatomically clearly distinguishable centres. Some are responsible for details, others for the total view.
Poerksen: In the process of perception an event first becomes a stimulus, which is then translated into the language of the brain and processed in certain places so that it gains further specificity. Is this happening all the time; is something new happening every time?
Roth: No, at least not with adult human beings. Many details of what we see, hear, and construct as adults are not supplied to the brain by an actual process of perception but by memory. The ingenious cognitive skill of remembering is what makes memory effectively our most important sense organ: a brain with years of experience, if placed in some arbitrary situation, can establish within seconds whether it is familiar with the environment. When after a few milliseconds the unconscious feedback reports that the situation is familiar, that I am in my study, for instance, memory will at one stroke produce the image of this room. The re-enactment of the image, released by only a few sign stimuli, is far quicker than it would be if the eye had to scan the environment atomistically every single time. This is to say: the process of construction only very rarely runs through all the laborious details that I have described. It does so with babies and small children; with adults only, when they find themselves in a completely unfamiliar environment. As a rule we can, however, because of our experience, see within moments what the matter is.
The step theory of communication
Poerksen: Up to now, we have been dealing with a particular constellation: there is a clearly discernible external stimulus that is processed. In the world of thinking, however, which so fundamentally conditions our reality, such an unambiguous input is lacking; there is no clearly defined external stimulus releasing just one specific thought. How far has cognitive neurobiology progressed in the explanation of what goes on in the mind?
Roth: We know today that the wiring of the cortex that is responsible for our conscious experiences shows that it is essentially busy with itself. An excitation that is known to come from outside is followed by 100,000 excitations inside the brain; a single scrap of information is processed by 100,000 instances. Only a small number of the perceptions of adult humans are related at all to external sensory stimuli, they are increasingly taken from memory. Thinking increases this constructivity of the brain, and the detachment from external events reaches a new level: thoughts and images are clearly abstracted perceptions and derived movements. One of the sensational research results of recent years is that brain centres, which are active in the case of movements, are equally active when we see movement or even when we only imagine it. So much on the construction of thoughts in the individual reality of a single brain.
Poerksen: To what extent are the realities that we construct for ourselves, in fact, unique? You keep emphasising that human individuals live in very different perceptual worlds. Your claim is, however, evidently contradicted by observations and experiences that are easily accessible: we do not misunderstand each other all the time; we are able to meet at agreed times; we can make appointments in the future; we can, within certain limits, agree about seeing the same things. The problem arises, therefore, how our different brains and their realities have been aligned with each other, how mutual understanding becomes possible - despite all individual construction?
Roth: One of the well-justified claims of constructivism is that meaning, and information in the sense of meaning, cannot be transmitted. What we are exchanging in this conversation is sound waves to which we possibly assign different meanings in our brains. I cannot guarantee in any way that the sound waves I am producing will be given the meanings I desire and hope for. The receiver, and not the sender, constitutes these meanings. Nonetheless, under normal circumstances a certain mutual understanding will be achieved. The explanation is everything but trivial: the sound waves must set something in motion in the inner ear; the auditory system must be attuned to the specific frequencies of human speech. An ant’s brain cannot construct language from the same sound waves; a dog may learn it, but the capability of speech recognition is innate only to human beings. A further prerequisite is that we can instinctively recognise and comprehend certain speech sounds - threats, flattery, moans, etc. - independently from any natural human language. Communication proper, finally, rests on a shared language, which does not, however, guarantee mutual understanding. The next building block and the next step are provided by a similar education: it safeguards the assignment of at least comparable meanings to the same words. The last step of communicative ability requires common life experience. Complete understanding remains an illusion, however, although we may expect a stepwise increase in the probability of the same words generating the same meanings in our minds.
Poerksen: Does this step theory of communication imply that we are fundamentally lonely even when we have reached the ultimate plane, the last step?
Roth: Yes. We remain locked into our own cognitive worlds. Maximal communicative understanding probably occurs with people living together for many years. Everybody knows, however, that even partners of many decades may have radically different views of the meaning of certain expressions. Every individual, therefore, not only develops a peculiar cognitive system but also an individual linguistic system. People decide about their semantic universes in early childhood - in shocking detachment from the meaning universes of others.
Poerksen: In one of his papers, Heinz von Foerster once offered an enlightening reformulation of the questions and topics we are discussing here. He called brain science the one-brain problem. The situation of the two-brain problem is represented by marriage and education: here one single brain influences another brain. The many-brain problem is society. My question is now: how do all these many different, individually constructing brains connect to form that strange structure which we call society?
Roth: It is not at all difficult to explain because two central mechanisms are at work here. On the one hand, it is possible, through common education and socialisation, intellectual training, feedback and mutual correction in conversation etc., to strengthen the consensual domains temporarily, whenever necessary. This is the basis and the result of all long-term interaction, of all common planning and collective searching for the solution of problems. On the other hand, we must be aware that the brains making up a society do not need to understand each other totally all the time, but only partially, and only in certain situations - if at all. When I buy a ticket from a train conductor, it is irrelevant whether he has seen any of my articles on brain physiology or whether he finds me a nice person. We must simply manage to communicate on a certain required level, unperturbed by the indisputable fact of fundamental incomprehension. But the use of language permanently suggests, of course, that we basically understand each other, that we comprehend the worlds of others, even when this happens to be untrue. However, I claim that the primary function of language is not mutual understanding. The perpetual public and private talk, similar to the permanent twittering of birds, serves mutual comforting, sedates our nervous system, and signals: we are friends, we do no hack each other to pieces, everything is all right. The contents appear to be quite irrelevant. Minimal societal cohesion is produced particularly in the form of common emotional experiences; it also results from non-verbal communication. We all yell in the football arena, we all get worked up over some scandal, we organise ourselves against some threat - and suddenly society arises.
The brain in the group
Poerksen: We see, you say, with the visual centres in the brain; perceptions are correlates of brain activity; meanings are personal. Another view proposes, however: we do not see with the visual centres of the brain but with the eyes of a group, of the social community and the linguistic and cultural world we come from. We construct a world together; meanings exist above the individual. How could your biological constructivism (the theory of the single brain) be connected with social constructivism (the theory of many brains)? They definitely contradict each other.
Roth: No, not at all. The first axiom is that everything concerning the construction of our world passes through our brains. The second axiom is, however: the individual brain of a primate would never reach full maturity in the “normal” way outside a group of primates. For us to become human requires the immediate proximity and the sign stimuli of other primates from the moment of birth; our brain craves in an elementary and dramatic way the voice and the warmth of the mother, the proximity of the father, the provision of food. We must see individual and social collective together. The individual brain needs the presence of the group unconditionally and existentially. An ape on its own is no ape, as Konrad Lorenz already remarked. And we are apes.
Poerksen: You believe that humans are apes?
Roth: What else? Naturally, constructivism with is fixation on rationality prefers to envisage an autonomous self and a glorified linguistic creature that constructs its particular reality in an act of conscious decision. We are not so very different from other animals, though. There is empirical evidence now that humans are also controlled by smells in large measure. We just do not notice because our organ of smell has no direct access to our cortex, and therefore we do not become aware of these control processes. It is now well known that the socially transmitted smells, the pheromones, strongly influence whether we find each other appealing or unappealing. In experiments, people were given batteries of armpit sweat to smell and asked to classify the various odours along a scale. The resulting, widely varying, appeal values were then used to perform a highly interesting experiment: young men and young women, unknown to each other, who had judged each other’s odour to be extremely appealing, are brought into contact. It is found that they do indeed find each other extremely appealing and that they fall head over heels in love because the minute odorous stimuli have reached their brains and released the corresponding behaviour.
Poerksen: Hearing the experience of love described in this way immediately releases a humanities-conditioned reflex - and raises the reproach of reductionism. The fundamental formula of reductionism is given by the statement: Falling in love is nothing but the mutual stimulation by odours. Are you a reductionist?
Roth: If the description that I have just given makes me a reductionist in the eyes of certain philosophers, then I am not at all impressed but really rather pleased. All I am interested in is to establish whether a hypothesis is consistent and coherent within defined limits of knowledge, no more. People who cast doubt on the results should check them and not withdraw from the game by devaluing them. Such behaviour has nothing to do with science. What would you say if I managed to present such an experiment and to demonstrate that it is possible to calculate precisely which of the subjects will fall in love with each other?
Poerksen: I would object that your experiment and its interpretation do not adequately cover the essential dimension of the experience of people falling in love with each other.
Roth: This is correct but it does not at all contradict my fundamental considerations: we first experience many things unconsciously that only later reach our cortex, and thus enter our awareness - and then start to scream for an explanation. Obviously our mind cannot simply accept the bare fact of falling in love; it demands verbal processing, individual stories, which can, of course, take place only after the preceding unconscious decisions.
Poerksen: Does the kind of biological reductionism that you are presenting here include the activity of the human mind? One of the creators of the DNA-model, Francis Crick, once said: “The self, its joys and sorrows, memories and desires, the feeling of personal identity and free will, are nothing but the behaviour of a large number of nerve cells.” Would you agree to that?
Roth: No. Francis Crick has never - as far as I know - investigated neurons in his life but dealt with other things, as we know. His pertinent knowledge is exclusively derived from reading and talking to neurobiologists. I have been investigating neuronal processes for 20 years, and I do not at all consider myself as a protagonist of a reductionist approach. What we can say today is that mental phenomena recognisably arise whenever very many neurons in an extremely complex network interact in a highly specific manner. The close correspondence between certain brain processes and mental phenomena does not at all endorse the thesis that mind and consciousness are nothing but firing neurons. I would never assert anything like that. A close correlation between neurons and mind does not mean identity, even though neuronal activity is undoubtedly a necessary condition of the phenomena of mind and consciousness.
Worlds of science
Poerksen: The history of modern science can be written as a story of continual offence. With the discovery by Nicolaus Copernicus, the earth ceased to be the centre of the universe. Following Charles Darwin’s doctrine, humans are naked apes. According to Sigmund Freud’s teachings, they are governed by unconscious drives. Richard Dawkins claims that we are vehicles of our selfish genes. Some people seem to be worried that neurobiology may, in the end, add to these offences: the imminent threat is the decoding of the mind. How do you come to terms with your own research goals? Do you experience them as offensive?
Roth: No, I do not. I think that modern brain research is, at present, merely confirming what people with adequate insight into the human mind have known for ages. It has been known all along that human beings live in their own small and peculiar worlds and are prone to aggression, that the unconscious control of behaviour triumphs over their conscious motives, that being in love is a matter of fate, a sort of disease. All this is not new. So why get excited? Why feel offended? Being confronted, however, with the latest findings of genetics that humans and chimpanzees are related much more closely than chimpanzees and gorillas, is indeed extremely disillusioning. One gulps - and in all the nasty dealings among chimpanzees one detects an enormous similarity to certain human ways of behaving - and vice versa.
Poerksen: One of your books is entitled Interface Brain. The thesis you elaborate is that the brain is an interface between mind and matter, absolute reality and constructed reality, biology and society. Could there also be, with regard to a neurobiology of consciousness, an interface between the natural, and the cultural sciences? Could the brain initiate and sustain a novel kind of interdisciplinary cooperation? Is the age of division over?
Roth: I have never believed in this division. Brain research must be supported by psychology and psychiatry. How can we possibly investigate memory without the treasures hoarded by the psychology of memory? How could you ever work without the knowledge accumulated by psychiatry and neurology? Without the research into brain lesions performed by these disciplines, we would know next to nothing about the human brain. The social and cultural sciences also contribute by investigating the influence of social rules on the brain. A cooperation with Egyptologists, German or Romance philologists, is not in sight, however, because the subject matter of the respective disciplines is too disparate. In addition, there are fundamental difficulties hindering the cooperation between these disciplines. The reason is not that the explanations of human behaviour by the natural and the cultural sciences might be incompatible, in principle. That is not the point. My criticism of many cultural scientists is quite simply that they do not practise any kind of science in the proper sense. They claims they put forward owe their existence to purely private reasoning.
Poerksen: It may be objected, however, that natural and cultural scientists are fundamentally different and, therefore, diverge in their practices of enquiry. Natural scientists, it has been asserted since the days of Wilhelm Dilthey, deal with the general, the law-like, and the immutable. Their goal is the explanation of the processes in nature. Cultural scientists are, by contrast, connected with their subject matter in quite a different way; they deal with the mutable, with phenomena arising through the historical development of human individuals and social processes; they want to understand cultural products.
Roth: My view is that there is only one kind of science, which is practised with diverse methods. There are no two essentially differing ways of attaining knowledge that may both be called science. When natural scientists make claims, they try hard to supply evidence to confirm their theses, they quote corroborating witnesses or their own investigations, adduce sources and statistics that are accessible for examination. That alone is science. You state something and you provide arguments, you expose yourself to the critical debate of qualified experts. Many cultural and social scientists, on the contrary, proceed as follows: they settle down at their desks and think up something as excitingly original as possible. Purported scientific knowledge is thus transformed into a pure emanation of intuitive claims.
Poerksen: I have the impression that you equate science with empirical procedure.
Roth: That is right. There is no science without empirical method. Nobody has so far managed to prove the contrary case. Whoever wants to achieve scientific progress must struggle for minimal consent. Without consent, there can be no science and no progress of knowledge. Otherwise, everybody is just shooting their mouths off. We therefore need procedures that are open to examination. In today’s social and cultural sciences, however, which are without empirical foundation, that consent is conspicuously lacking. The persistent proclamation of differences and theses with a somehow novel and exciting ring but without any connective potential has, regrettably enough, become a career booster. Natural science proceeds differently. Natural scientists today cannot with impunity simply turn current theories upside down in order to gain heightened attention; they must produce knowledge with connective potential.
Poerksen: My worry is that your conception of science will ultimately lead to an unproductive homogenisation of ideas. If I follow you, the distribution of conundrums and the generation of productive irritations will no longer be justified.
Roth: Nobody forbids a philosopher or a cultural scientist to develop their own ideas and to voice their criticism of the results of the natural sciences - that is not the point at all. Irritations, stimulating proposals, and the revelation of contradictions and inconsistencies will always be most welcome, but they must have integrative potential and admit of experimental or logical testing. Of course, I can insist with glee that the earth is a disc and that brain and mind have nothing at all to do with each other. But I must in such circumstances also be prepared to face the strong empirical evidence contradicting such claims. You should not join the philosopher Hegel in saying: too bad for the empirical facts! That is all I am saying. Who claims to put forward scientific statements must take account of all available research and all relevant counterarguments.
The third culture
Poerksen: Pushing this plea for the orientation towards tradition and established knowledge to its extreme, you might encourage the founding of an insider club dedicated exclusively to the everlasting protection of the mutual affirmation of conventional practices. I believe, however, not just for aesthetic reasons but for the sake of scientific progress, that we should keep all the barriers and frontiers permeable and also permit entry to alleged cranks, jokers, and birds of paradise. They are indispensable for getting things moving.
Roth: I am also open to quirky ideas and crazy experiments whenever there is an explanatory gap. To explain the fact, however, that a glass window can be smashed to splinters by a stone does not require new theories, nor do I have to design new experiments or revive Aristotelian impetus theory; the splintering of glass can be explained excellently by the models of contemporary physics. However, nobody yet knows how cognition emerges from brain processes. Here we face an explanatory gap that invites creative impulses and ideas. But they must be subjected to experimental examination. If people are not prepared to undertake this drudge of experimental testing, the threat of waffle by charlatans arises, who boast their importance with verbal trickery on the circus stage of science and parade their theories on the quantum mechanical processes of the rise of consciousness, for example, or on other sparks of their imagination. And at some stage the question has to be answered how to identify the most inspiring charlatan in that crowd of busybodies. Whom should I pursue, and for what reasons, should I want to deal with some hypothesis in a more precise way? What criteria do I have? Of course, I could say: I declare this problem one of aesthetics, and I shall rush after Bernhard Poerksen because he is wild in the most beautiful manner. However, this is not really a satisfactory solution.
Poerksen: I suspect that your concept of science will be generally accepted before long. I can offer circumstantial evidence. There is a most successful war cry that is raging through the academic universe now, and that clearly and explicitly assigns those cultural disciplines that do not employ empirical methods, the footstool in the business of meaning production. This war cry stems from a book by the New York literary agent John Brockmann. He describes - with reference to C. P. Snow’s thesis that natural and cultural sciences form two disparate and hostile cultures - a third culture. The problems originally dealt with by the cultural sciences, he claims, are now articulated within the medium of empirical scientific research. Brain research and constructivism endorse Brockmann’s thesis: old philosophical questions are today being answered by scientists.
Roth: That I would object to: there are no two cultures, nor is there a third culture; there is just one and only one science, just one single culture of scientific cooperation in thought and action. It is not specific to the natural or the cultural sciences, but it is firmly anchored in an intersubjective form of knowledge production. My own field of expertise - brain research - appears to me, with reference to the German terminological tradition, as a geisteswissenschaft of a special kind. As a scientist, I investigate the brain, simultaneously dealing, however, with the mind, and showing that the phenomena of the mind are most closely linked to the physiological phenomena. For certain philosophers, such a research programme is sacrilegious in itself; the mind as the highest ontic state can, in their view, have only one function, i.e. to comprehend itself. Nevertheless, as a cognitive neurobiologist, who works in the laboratory, I am interested in understanding how we think, how we hear melodies, understand language, enjoy the smell of a rose, how memory functions, how my attention is directed, how the brains of a normal human being and a genius work and function. And at some stage, I firmly believe, we will be able to explain what was special about Johann Sebastian Bach’s brain and enabled him to write all those incredible compositions. Such an explanation of what has hitherto remained mysterious is most certainly not a threat to a genius like Johann Sebastian Bach and his music. It does not in any way destroy its exquisite nature.
Poerksen: Speculating for a moment: will there always be an inexplicable residue?
Roth: My view is that the framework of scientific enquiry will always remain limited - and that it cannot be stretched to encompass questions that concern, for example, why I might exist on this planet as a single human being, why I am able to think, what the meaning of my life is, how the universe began. We are left with a long list of mysteries on which we cannot, however, definitely pronounce that they will remain perplexing forever or perhaps be revealed at the time of death or at some other moment. The limits to our knowledge cannot be known either; otherwise, they would no longer be limits.
Poerksen: The consequence?
Roth: The impossibility of establishing the limits on our knowledge is an empty idea. The consequence? Nothing at all. Nothing.