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Tallis in Wonderland

Perception as a Controlled Hallucination

Raymond Tallis argues against calling everyday experience a ‘hallucination’.

Over the festive season, in the intervals between eating, drinking, Covid-secure socializing, and giving and receiving gifts, I read Anil Seth’s Being You: A New Science of Consciousness (2021). Beautifully written, with its wonderful erudition worn lightly, it is a must-read. It gathers up in one relatively short book the strongest possible case for believing that we are getting closer to understanding “how the various properties of consciousness depend on, and relate to, the operations of the neural wetware inside our heads” (p.5). Yet after reading Being You, the reader may see why ‘the strongest possible case’ falls well short of being strong enough.

Regular readers of this column will be familiar with my allergy to Neuromania – the conviction that the brain is not only a necessary condition for human consciousness and indeed personhood, but also a sufficient condition: the idea that consciousness ‘is only’ brain activity.

There are many reasons for acknowledging the brain as a necessary condition for citizenship of the community of minds. Brain damage results in loss or impairment of consciousness and of aspects of personhood, and there are rough correlations between the sites of damage and the mental deficits that result. What’s more, localized stimulation of the cerebral cortex in waking subjects may result in the production of a range of experiences, from simple tingles to the evocation of detailed memories. There are, however, also many reasons for not concluding from this that what goes on in the brain is sufficient for consciousness and personhood, or that brain activity is identical with the contents of the conscious mind. Most obviously, neural discharges are nothing like, for example, the experience of the colour yellow, of knowing that Paris is the capital of France, or experiencing nostalgia or regret. More fundamentally, physical events such as nerve impulses in the brain are radically different from anything that has the ‘intentionality’ or ‘aboutness’ that is the mark of the mental. Events in the visual cortex do not seem to have the capacity to point upstream to the events that have caused them, and to transform those events into the basis of the experience of an object encountered by a conscious subject, such as the experience of seeing a flower. The gap between neural activity and consciousness is even wider where intentional consciousness is shared or joined with that of the consciousness of others so that a community of conscious minds – the world of our daily life – is created and maintained. It is consequently difficult to identify anything that happens in the darkness inside my skull with my being a citizen of many worlds. There are also other characteristics of persons and their minds that cannot be revealed by even the most careful inspection of neural activity; for example, experiential unities, such as those in a visual field, where many elements are brought together and yet are kept distinct, so that we can simultaneously see both individual objects and the landscape of which they are a part. And then there is memory. The explicit presence of the past (which also informs an envisaged future) has no place in the physical world. A brain at time t is confined to time t. By contrast, a person at time t reaches back into time t-1 and forward into time t+1 – to many-layered realms of the no-longer and the not-yet, which are necessary for our present moments to have explicit meaning and significance.

Eye Hallucination
Eye Hallucination © Paul Gregory 2022

Information, Information, Information!

A good deal of ingenuity is therefore needed to leap over the yawning gap between persons and their neural wetware. One strategy can be summarized as brainifying the person by personifying the brain, which brings me back to Seth’s Being You. According to Seth, notwithstanding that they are tenseless material objects, brains are ‘prediction engines’: they reach into the future with guesses, hypotheses, inferences, and so on. Personifying the brain in this sort of way is of course commonplace in neuroscience, and in physicalist philosophy, which identifies consciousness with neural activity and persons with their brains. The term that is put to most use in this context – indeed it is worked to death – is ‘information’. The brain, we are told, is an information processing device. This seems obvious to those who a) think of the brain as a computer, and b) believe that stand-alone computers process information.

Calling what happens in a physical object such as a brain ‘information processing’ is hardly controversial if it is accepted that information is everywhere. Indeed, if information does not require conscious subjects who are informed, or who inform others, there is no limit to where information can be found. David Chalmers raised fewer eyebrows than he should have done when he asserted that “wherever there is causal interaction, there is information… One can find information states in a rock – when it expands and contracts, for example – or even in different aspects of an electron” (The Conscious Mind: In Search of a Fundamental Theory, 1996, p.297).

If, however, information really is everywhere, then seeing the brain as an information-processing device contributes nothing to explaining how it is the seat of consciousness. This is one of the reasons why Seth rejects the idea that the neural activity/consciousness gap can be closed by describing both as ‘information’. He remains, however, in the penumbra of this conceptual framework, and retains its associated personification of the brain as a prediction machine: “what we see, hear, and feel, is nothing more than the brain’s ‘best guess’ of the causes of its sensory inputs” (p.76). From this he draws an interesting conclusion: the experienced world is ‘a neuronal fantasy’. It is the product of ‘top-down predictions’ generated by cerebral tissue rather than ‘bottom-up’ sensory input. Perception is, apparently, a controlled hallucination.

A Fantasy of Hallucination

If we set aside the qualification ‘controlled’ for the moment, this sounds like a radical, indeed radically disturbing, claim. Seth’s appeal to well-known illusions such as Adelson’s checkerboard to support his thesis should, however, raise our suspicions, not the least because illusions are not hallucinations. More significantly, if perception really were universally hallucinatory, we should not be able to identify within that perceptual experience a small sub-set of our experiences betraying or illustrating this fact. But that I can be tricked into getting things wrong, and then recognize this, itself shows that I don’t always, or even typically, get things wrong.

If, moreover, the brain generates only a ‘top-down fantasy’, how would we get to know this supposed truth about our experience? By what means would we get past the fantasy to call it out? ‘Science!’ is not an answer here because ultimately science too depends on perceptions. If perception were the ever-deceptive epistemological prisoner of the brain, there would be no means by which scientists could expose what the brain is up to, never mind share the news that daily experience is a controlled hallucination.

It would appear, after all, then, that the ‘neuronal fantasy’ is so completely reined in by reality that it is not a fantasy at all. Sense experience is no kind of hallucination, controlled or otherwise. If I have the experience of seeing a cup in front of me and there is a cup in front of me (as is usually the case), this is not a question of experiencing any kind of hallucination, controlled or not. An ‘hallucination’ so tightly controlled by the kind of reality that we can all see if we are correctly positioned, seems indistinguishable from veridical perception. So isn’t the situation just what we thought it was all along?

Seth’s further claim that our conscious perceptions are “indirect reflections of hidden causes that we can never directly encounter” (p.80) also seems to undermine itself in similar ways. By what (indirect) means did we discover those hidden causes? And how did we discover that our predictions are “tied in useful ways to their causes” if the causes are hidden?

Of course, our experiences prompt expectations arising out of the objects of our perception, and those expectations may be unfulfilled. Life is speckled with surprises, and we sometimes make mistakes. When I see a coffee cup, I expect I will be able to pick it up. I may be proved wrong: some joker has super-glued it to the table. On the overwhelming majority of occasions, however, my implicit expectations about the world of everyday perception will be borne out. I may occasionally encounter a trip-wire, but the rarity of such events justifies the usual belief that any ‘top-down inferences’ I may make in my perception are located in a sea of experiences that are not merely the ‘guesswork’ of a personified brain.

It may seem as if I am being wilfully dim. Of course, there is a sense in which we never see objects as they are in themselves, and there are obvious grounds for taking the deliverances of our senses with a pinch of salt. Groping in the dark is an incomplete revelation of the item groped. And even the most object-friendly sense, vision, reveals only part of a surface of the object, and does so from an angle and at a distance and in a light which the object itself has no part in defining. Generally speaking, how objects are perceived is influenced by the nature of their interaction with the perceiving subject. This is not however distortion or concealment; not the least because when, for example, I see an object from a certain angle, I see that I am seeing it from that angle and make allowances. When I see something in unfavourable conditions, I am conscious that my seeing is dodgy guesswork.

Challenging the ‘revelation’ that brain science has exposed perception as a neuronal fantasy also throws into question the adjacent claim that we’re closing in on an explanation of how there come to be subjects facing a world of objects. The intact mystery can be highlighted by noting an asymmetry: while there is a realm of material objects, states, and events present to subjects like you and me, we are not present to the material world. The cup I experience does not experience me. Fancy footwork - around supposed causal interactions between extra-cerebral entities and bits of the brain credited with the capacity to guess or predict what it is that is outside the body of the person whose brain it is - does not cast any light on this fundamental asymmetry.

It is in the context of this thought that we may judge the promise with which Seth’s book ends: that “We will see how our inner universe is part of, not apart from, the rest of the universe” (p.276). To look half-way persuasive this promise of a journey towards a completed naturalism requires more than the arguments and experimental findings set out in the preceding 275 pages. I nevertheless urge you to read Being You: A New Science of Consciousness. There could not be a better account of the state of the art of the scientistic philosophy of mind – and hence no more elegant, if inadvertent, exposure of its limitations.

© Prof. Raymond Tallis 2022

Raymond Tallis’s latest book, Freedom: An Impossible Reality was published recently, and reviewed in this issue’s review section.

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