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Tallis in Wonderland

Reflections On Epilepsy

Raymond Tallis applies his mind to his mind.

My experience with neurological patients has underlined what ordinary life tells us: that a brain in some working order is a necessary condition for human consciousness. Unlike mind-brain identity theorists, however, I do not believe that consciousness is identical with neural activity in the cerebral cortex, the brain stem, the thalamus or wherever. This does not mean that I think I have an immaterial soul; nor do I subscribe to a ‘ghost-in-the-machine’ Cartesian dualism. Rather, I am a non-Cartesian atheist who just can’t help noticing that however hard you look, you will not find sensations, affections and reasons in bits of the brain, or even distributed throughout the brain. So although a functioning brain is necessary for every aspect of consciousness, from the simplest twinge of sensation to the most exquisitely constructed sense of self, it is not sufficient for consciousness – and certainly not for the kind of consciousness you and I enjoy.

A necessary condition, or set of conditions, of something happening, is that without which it will not happen; a sufficient condition, or set of conditions, is that which is enough to ensure that it happens. In order for me to be knocked down by a 97 bus in London, it’s necessary for me to be in London. However, being in London is not sufficient – otherwise I might be even more inclined to avoid the place. Something else is required – for example that I should be in a certain street; that a 97 bus should be in the same street; that, preoccupied with the mind-body problem, I should walk in front of the bus; and that the driver, who may also be pondering the mind-body problem, should fail to see me in order to stop in time.

The philosophical literature on necessary and sufficient conditions (and the difference between ‘causes’ and ‘conditions’) is immensely complicated, but the main point is that there is a gap between them: something is required to get from one to the other. We shall not make progress in understanding consciousness and its relationship to the brain and our organic being, until we recognise that gap, and then form some idea of what is in it.

It is easy to specify this void in very broad terms. First, a brain requires a body, not only in order to survive, but also in order to have something to work with; and the embodied brain requires a physical environment. Mind-brain identity theorists would probably concede this, despite their claims to find this or that bit of consciousness in this or that bit of the brain. However, they would still argue that consciousness boils down to activity in the brain. But in the case of a human brain and consciousness, I maintain, more – much more – is needed. We humans are not just organisms. We are persons operating in a public space of a kind not known elsewhere in nature. This space – the human world, a community of minds – has been built up over a shared history that reaches into a very distant past. This additional condition underlines the futility of looking for consciousness in the activity of the individual brain; even more of looking for the phenomena of everyday consciousness, such as love, or reasoning, or the appreciation of jokes, in parts of that brain.

For many years I used to run an epilepsy clinic. Epilepsy is a condition in which abnormal electrical activity in the brain, occurring spontaneously yet highly synchronised, causes episodic disturbances of normal brain function. The characteristics of the seizures depend on the location, the spread and the duration of these abnormal electrical discharges. The most striking features include loss of consciousness, confusion, and convulsive movements. These seem to be adequately explained by the idea that the discharges take over normal brain (electrical) activity – a conclusion that is entirely compatible with normal neural activity being a necessary but not a sufficient condition of consciousness. Even positive symptoms such as convulsions can be understood in this way as well: the very fact that the movements are meaningless twitches underlines how mere neural activity in the stand-alone brain is not sufficient to account for ordinary human behaviour.

We can see this when we look beyond the seizure to the patient’s response to it. Whereas we can readily correlate the impairment of consciousness and the stereotyped, rhythmic movements seen in some seizures with abnormal cerebral discharges, it is a massive assumption to say that we can correlate such discharges with the patient’s decision to go to see the doctor, his organising a friend to babysit while he does so, and his willingness or otherwise to trust the doctor, accept her advice and be willing to embark on a lifetime’s course of medication. There is a distinction, in short, between the epileptic fit and the person who has the fit and the actions by which he tries to cope with it.

Some will not be impressed by this distinction between having a fit and coping with it. The distinguished neuroscientist and mind-brain identity theorist Colin Blakemore has even argued that ordinary behaviour is fundamentally the same as having a series of seizures: he says that since the human brain “accounts for all our actions… [it] makes no sense (in scientific terms) to try to distinguish sharply between acts that result from conscious attention and those that result from our reflexes or are caused by disease or damage to the brain.” ( The Mechanics of the Mind, 1988.)

This shows up the absurdity of the mind-brain identity theory. I must admit, however, that there are some phenomena that do seem to throw into question the sharp contrast between epileptic seizures that are adequately explained by the activity of the stand-alone brain, and ordinary human consciousness that is not. There are, for example, forms of epilepsy involving the temporal lobes, a part of the cerebral cortex, which result in experiencing very complex images or indeed entire scenarios. Does this not suggest that the stand-alone brain has the wherewithal to generate at least fragments of consciousness on its own?

Even more challenging are some observations made by the neurosurgeon Wilder Penfield. Penfield pioneered surgical techniques for treating otherwise uncontrollable epilepsy by removing irritable tissue in the brain where the seizures originated. Since it was vital not to cut out parts of the brain essential for speech and other key functions, the operations were carried out in waking patients (the brain itself does not experience pain), so that, prior to the excision, Penfield could map the location of different functions in the brain using stimulating electrodes. When the temporal lobes were stimulated, some patients reported very elaborate experiences, or rich and detailed memories. This seemed to support the notion that the stand-alone brain could be the basis for complex consciousness. In accordance with the famous thought experiment put into circulation by the American philosopher Hilary Putnam, it even suggested that a ‘Brain in a Vat’, stimulated by appropriate inputs through its nerve endings, could believe that it was in a world.

However, neither the experiences of people with epilepsy nor Penfield’s observations justify this conclusion. Take the ‘memories’ reported by Penfield’s patients (seen, by the way, in only 5% of his subjects, and not replicated by contemporary surgeons): they are essentially ‘second-hand’ or ‘recycled’ memories. No-one who has not had experiences remembered in the usual way would interpret what was happening as a memory – even less as a memory with a particular significance, meaning or reference. The Penfield phenomena, like the pseudo-experiences of temporal lobe epilepsy, are simply re-activated memories of experiences had in the real world, not by an isolated brain, but by a person. The electrical activity in the brain as isolated in Penfield’s experiments appears to have the ‘aboutness’ or what philosophers call the ‘intentionality’ of normal experiences only because under all othercircumstances (ie, when the patient is not having a seizure or undergoing electrical stimulation) the experiences are genuinely of something that is really ‘out there’ – really happening, to a real person.

Our ordinary memories, and our ordinary current experiences, make sense because they are part of a world. Yes, we are located in this world in virtue of being embodied, and we access it through our brains; but it makes sense to us as a world not solely on account of its physical properties, but as a network of significances upheld by the community of minds of which we individually are only a part. The Brain in the Vat thought experiment helps itself to this world free of charge – a world, incidentally, in which, in addition to electrode-induced experiences, there really are material brains, electrodes, vats, scientists and the institutions, practices and knowledge which supports them. The hallucinations induced in the stand-alone brain by electrical stimulation or epilepsy seem to make brain electricity a sufficient cause of experience only because they, too, parasitize a real world already experienced in the usual way. (Indeed, according to the doctrine of disjunctivism – a major area of interest in contemporary philosophy of mind – hallucinations and genuine perceptions, though they may seem the same to the person experiencing them, have nothing else in common.)

There is a deeper point. Consciousness, fully realised only in humans, transcends the material world of which the organism is a part: when we experience something, the experience explicitly points to an object other than itself – and, indeed, other than myself. The explicit ‘aboutness’ or ‘intentionality’ of my experience – whereby, say, you see a glass as ‘over there’ – cannot be explained in simple causal terms. In seeing the glass, I am, as it were, looking causally upstream, to the source of the light that has arrived on my retina. This counter-causal direction of intentionality is the foundation of our sense of being in a world, and it lies at the root of the pooled transcendence that is the public space of mind in which we humans live our lives. This public space has been built up over tens of thousands of years by many millions of individuals. Mind-brain identity theorists try to stuff this public space back into the individual brain, or into parts of it, in order to deny its extra-cerebral, indeed trans-organic, reality.

If neural impulses in a solitary brain were sufficient to make up a world – as opposed to simulating bits of worlds under very abnormal circumstances – then we should not be able to distinguish between having a series of epileptic fits and living with epilepsy – or, indeed, living without epilepsy. I used to shudder when I heard people with epilepsy referred to as ‘epileptics’. By identifying the patient with his brain condition, it collapsed the distance between the latter and the person who coped with it (and decided whether my advice was any good or not). This was not only dehumanising but also metaphysically wrong.

Raymond Tallis is a physician, philosopher, poet and novelist. His book The Kingdom of Infinite Space: A Fantastical Journey Round Your Head is published by Atlantic.