Consciousness & the divided brain

12/12/2019 Consciousness and the divided brain Address to the Australian Psychedelic Society (Brisbane) Meeting Room, Brisbane Square Library, 266 George Street 11 December 2019 Consciousness It is impossible to meditate on consciousness ... without an overwhelming emotion at the limitations of human intelligence — William Grey (with apologies to A.N. Whitehead) William Grey Honorary Research Associate Professor in Philosophy School of Historical and Philosophical Inquiry University of Queensland What is the mind-body problem and why does it matter? • How it is that anything so remarkable as a state of consciousness comes about as a result of irritating nervous tissue, is just as unaccountable as the appearance of the Djinn when Aladdin rubbed his lamp • Thomas Huxley (1825-1895), The Elements of Physiology 1869 • The greatest mystery [about brain function] is that each of us is conscious of our surroundings. One can visualize how sets of nerve cells could make an animal work as an automaton; but how this could give rise to conscious experience is something one can't yet see what kind of solution there would be • It's a degree more difficult than the sort of problem of how the nervous system works, which although unimaginably complex, one can visualize that it might be like a computer, enormously more complicated that any existing computer • ... One doesn't see any way into answering that question • Andrew Huxley (1917-2012), ABC Science Show, 17 April 1982 Leibniz (1646-1716): the “mill” argument • … perception, and what depends upon it, is inexplicable in terms of mechanical reasons, that is through shapes, size and motions. If we imagine that there is a machine whose structure makes it think, sense, and have perceptions, we could conceive it enlarged, keeping the same proportions, so that we could enter into it, as one enters a mill. Assuming that, when inspecting its interior, we will find only parts that push one another, and we will never find anything to explain a perception. And so, one should seek perception in the simple substance and not in the composite or in the machine. • G.W. Leibniz, Monadology (1714), sec 17 Between Biology and Psychology • Conscious experience is clearly (well, obvious to us) coupled with neurobiological processes. The problem is making sense of this relationship • There are natural levels of organisation in the physical world • Roland Burton Hedley III is best known for his 1980 election-eve expedition into Ronald Reagan's brain • Six years later he mounted a deja vu follow-up expedition in an effort to jar loose presidential Iranscam memories Physics  Chemistry  Biology  Psychology • Each level in some way supervenes on the level below 1 12/12/2019 Vitalism Is the Mind-Body Problem insoluble? • The relationship between chemistry and biology seemed intractable in the 19th century • Living systems manifested properties which seemed inexplicable by physics and chemistry • Inquirers in the 19th century invoked mysterious "vital forces" • In the case of biology the mystifying puzzles of life weren't intractable • The facts of reproduction, growth and metabolism are complex and astonishingly coordinated and controlled on many levels of molecular organisation • Deep and difficult problems, but no intractable mystery • Understanding biological systems, it turned out, didn't require vital forces. We could explain vital processes with physics and chemistry— in particular molecular biology. "Vital forces" evaporated! • Some philosophers think that the mystery of consciousness will eventually disappear in the same way as vital forces, and the mindbody problem, which confounded philosophers of antiquity, and which continues to challenge philosophers today, may vanish • Colin McGinn argues that there are epistemological reasons why the mind-body problem (or a central component of it) cannot be solved— at least by our sort of intelligence. It is conceptually intractable “Easy” and “Hard” problems “Easy” problems • David Chalmers distinguishes between "easy" problems and the "hard" problem of consciousness • We are organisms who can be described as complex systems with sensory (perceptual) inputs and behavioural outputs, and a lot of brain function can be understood and explained as processes which mediate (or modulate) behavioural output in a way that maximises benefits to the organism in relation to its environmental circumstances The "Hard"Problem • However making sense of the relationship between first-person conscious experience and the underlying neurobiological structures within which (we very reasonably suppose) conscious experience is somehow embedded is metaphysically puzzling • The problem concerns the mysterious connection between immediate conscious experience and what Huxley called "the irritation of nervous tissue“—which straddles a conceptual gulf • So long as we consider third person descriptive explanations of behaviour (explaining biological performance in terms of neurobiological mediated response to circumstance) the task is tractable • For example, we have a vast store of memories. How is that possible? • No problem – in principle • The brain is a hugely complex (massively parallel and multiply redundant) system, and there are more than enough discrete brain states to account for all of the memories which we store First-person and third-person knowledge • We have first-person psychological understanding of belief, action, desire, intention, etc (the disparate material of folk psychology)— there are plenty of (often helpful) theories about the mind • We also have third-person descriptive knowledge of biological (and physical) structures, and we understand a lot about neural architecture and broad structural features of the organisation and operation of the brain • The problem is connecting these epistemically disparate bodies of knowledge 2 12/12/2019 The “Hard” problem Bernard Williams on the problem of consciousness • The "hard" problem is making sense of how the deliverances of immediate first-person experience—the Djinn of consciousness (qualia, raw feels,…)— is related to our neurological architecture • This is an epistemological problem: it concerns our knowledge (or lack thereof) and our understanding of the way that our experience is related to the material world • We can distinguish between a metaphysical and an epistemological dimension to the mind-body problem (thanks in particular to Saul Kripke) • Descartes (famously) argued that the intractable gulf between mind (experience) and matter (extension) entails substance dualism • But McGinn and others argue (after Kripke), there is no need to draw this metaphysical conclusion from Descartes’ epistemological premise • The intractability is reflected in the wide range of opinion about the problem • We are not agreed that there is a problem; or, if there is, whether it has been solved; or, if it has not, whether it is soluble; or, if it is soluble, whether the present obstacles to our solving it are technical, theoretical, or conceptual • Bernard Williams 2006: 178 • It is hard to think of any other problem area in which so many impressions of the nature of our ignorance can coexist Responses to Descartes • Whimsical graphic (from Roderick Chisholm) illustrating some responses to Descartes’ problem • DUALISM • Interactionism (Descartes) • Epiphenomenalism (Huxley) • Parallelism • Pre-established Harmony (Leibniz) • Occasionalism (Malebranche) -- • Dual Aspect (Spinoza) • MONISM • Materialism (Hobbes) • Idealism (Berkeley) Concepts and Percepts • The problem (McGinn argues) is that our thinking about the world is sometimes conception-based (left hemisphere/representational/ third person) and sometimes perception-based (right hemisphere/ first person) • To solve the mind-body problem we would need some extended (or alternative) mode of cognition which supplemented (or replaced) our basic modes of understanding and which straddled the gulf that separates our perceptual and conceptual modes of knowledge • But we have no such alternative mode of cognition, and no idea of what such a mode of cognition would be like (in order to know what it would be like we would need to have it!) • The mind-body problem is therefore a problem that will continue to confound us—and also to confound any creatures who are cognitively constituted like us 15 Cognitive Hubris • Evolution has provided us with adaptively shaped cognitive apparatus to survive and reproduce in the world • But there is no requirement (or reasonable expectation) that our evolved cognitive apparatus should be able to make sense of every aspect of the world's intrinsic structure • And a particular instance of these cognitive limits is the inability of our cognitive apparatus to make sense of its own intrinsic structure Cognitive Hubris • It is astonishing how much of the world we can make sense of • We understand why the stars shine • We understand (roughly) the size, mass, and age of the universe • We understand the incompleteness of arithmetic. • The fact that there are some features of the world which we can't make sense of should be no more surprising than the cognitive opacity of Euclidean geometry to a cat • If the human brain were so simple that we could understand it, we would be so simple that we couldn’t -- Emerson Pugh 3 12/12/2019 Making sense of the world • How do we make sense of the physical world? • Empirical inquiry typically explores microstructures. Material macroobjects are composed of micro-components which we can track down through many levels of organization • Micro-components turn out to be bizarre and conceptually problematic. They are strange physical objects, but they are physical objects • But when we try to figure out consciousness it isn’t like that at all • Consciousness (we believe) is a product of a physical structure—the brain—but no physical description of brain structures captures the phenomenological experience of consciousness Subjectivity and objectivity • Immediate phenomenological awareness is grasped only from the inside (immediate acquaintance-based) • Neural structures are objectively describable but they are from the outside • Typically in solving a problem we deepen our understanding by transcending a parochial view. Stepping outside the deliverances of immediate experience, we come to see, e.g. that the earth is not flat, nor the centre of the universe • However we cannot step outside the parochial centre of first-person conscious awareness (in order to understand it better) The experience of awareness Solving the Mind-Body Problem • “Expanding our consciousness”, if it means anything, isn’t stepping outside our immediate awareness—it is incorporating more stuff within our awareness • To get an objective fix on awareness itself we would have step outside that awareness and observe it from the outside. That would be a state of nonawareness, not a vantage point from which to experience awareness itself • Awareness itself is accessible only through immediate experience; awareness is immediate experience. (The experience of awareness is the awareness of experience.) • Our conceptions of consciousness are acquaintance-based but any objective descriptions of conscious states are not • Maybe God can solve the mind-body problem • Or maybe some superior intelligence could intuit a direct link between experience and neurobiology (or its alien equivalent) • Such an intelligence would have an a priori understanding of how consciousness is based on (or emerges from) subconscious or unconscious sub-components • But we cannot • We are Djinns who understand some features of the lamp from which we emerged—but we have no physical understanding of our underlying Djinn nature An ironic deity? An ironic deity? • McGinn • McGinn shows how introspective self-consciousness helps us to understand the nature of the epistemological mind-body problem, and also how it blocks us from solving this problem • Importantly Descartes' metaphysical puzzle is dissolved—there is no need to resort to substance dualism (or epiphenomenalism, or occasionalism), or other desperate metaphysical “solutions” • As McGinn says: • It is almost as if we have been designed to be struck by a problem which we are constitutionally unable to solve…I can imagine a type of God for whom this would be an amusing irony—even an irresistible temptation (p. 25) • McGinn’s ironic (and perverse) deity would have delighted David Hume (1711-1776) • It is a deity that Hume might well have included in his Dialogues Concerning Natural Religion (1779)—if it had occurred to him 4 12/12/2019 The Upshot? • Self-conscious intelligence is capable of astonishing feats of knowledge, but there is an unbridgeable boundary which prevents self conscious intelligence (of our sort) from understanding itself. We can understand much about the world, but the conceptual apparatus we deploy for this task has limits • This isn’t an ontological (or metaphysical) problem. Consciousness or minds are not spooky non-material entities. They are the product of complex material entities. It's an epistemological problem. • We elucidate more and more of the complex neural structures that provide the scaffolding for conscious awareness, but our knowledge of the scaffolding (third-person objective descriptions) cannot cross a gulf which separates these descriptions from first-person conscious experience (upon which the third person descriptions are grounded) The divided brain • One factor which may be relevant to our understanding of the problem is the bihemispheric structure of the brain • Experience is processed in two different ways. There is a holistic synoptic processing of experience (right hemisphere) and narrowbeam focused awareness (left hemisphere) • Narrow focus attention (left hemisphere) enables us to exploit opportunities; synoptic wide-angle awareness (right hemisphere) enables us to detect and avoid threats. • (Focusing on the rabbit we are catching for dinner is important, but so too is avoiding the tiger whose dinner we might become.) Brain asymmetry This distinction between narrow-beam, highly focussed attention and broad sustained vigilance has been repeatedly described not only in mammals, but in amphibians, reptiles and birds, as well as in fish ... Indeed they have also been demonstrated in molluscs, nematode worms, and insects. And even in trilobites. Indeed the most ancient creature still extant, the 700 million year old Nematostella vectensis, also has a lateralised ‘neural net’. (McGilchrist) Left hemisphere hegemony • The left hemisphere is the analytic reflective component of the brain, largely responsible for language and for making sense of the world • Oliver Sacks says that the entire history of neurology and neuropsychology can be seen as a history of the investigation of the left hemisphere. (Split brain experiments provide wonderful insights into the function of the hemispheres, as well as raising challenging questions about the unity of the self.) • Oliver Sacks, The Man Who Mistook his Wife for a Hat (1985), p. 2 The bihemispheric brain • Sacks’ conjecture can be extended • Much of (perhaps most) philosophy (like neuropsychology) is a product of the left hemisphere • Immediate conscious awareness—unified self-conscious intelligence— is largely a product of the right hemisphere. My conjecture is that the intractability of the mind-body problem may be the result of the difficulty that the left hemisphere has in making sense of the right hemisphere • The right hemisphere doesn’t understand the left hemisphere either, though the situation is different. The right hemisphere's failure to understand the left hemisphere is because the right hemisphere (a locus of immediate experience) isn’t in the business of understanding (theorizing) at all. Understanding isn’t part of its schtick. 5 12/12/2019 Meditation • I conjecture that meditation is all about developing the cognitive discipline to shut down the continuing distracting chatter of the left hemisphere to allow the right hemisphere to bask in an unprocessed stream of (what William James called) the “blooming buzzing confusion” of immediate awareness. (Which is only confusing because of the left hemisphere's obsession of trying to make sense of everything) David Stove’s nosology • People are mostly sane enough, of course, in the affairs of common life ... But the moment they attempt any depth or generality of thought, they go mad almost infallibly • David Stove ‘What is wrong with our thoughts?’ The Plato Cult: 184 • The extraordinary plethora of responses to the mind-body problem may be a manifestation of the left hemisphere's obsession to understand and resolve the mind-body problem Conclusion • We cannot explain consciousness, but we can explain (or suggest) why consciousness can’t be explained • Knowledge of course has its limits • We can know that there's a boundary to what we can know even if that boundary can't be drawn. (I know that there must be a boundary to my visual field—because I can’t see behind me—but I can’t trace that boundary: to draw the boundary line I’d need to see on both sides of the line, and if I could do that then the line wouldn’t be the boundary!) END References • Chalmers, David (1996) The Conscious Mind. Oxford • Descartes, Rene. (1644) The Principles of Philosophy • Huxley, T H (1869) The Elements of Physiology and Hygiene: A Text-book for Educational Institutions. London • Leibniz, G W (1714) Monadology • McGilchrist, Iain (2009) The Master and his Emissary. Yale • McGinn, Colin (2004) Consciousness and its Objects. Oxford • Nagel, Thomas (1986) The View from Nowhere. Oxford • Sacks, Oliver (1985) The Man Who Mistook his Wife for a Hat. Picador • Van Gulick, Robert, "Consciousness", The Stanford Encyclopedia of Philosophy (Spring 2018 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/spr2018/entries/consciousness/> • Williams, Bernard (2006) Philosophy as a Humanistic Discipline. Princeton 6