The Ravenous Brain: How the New Science of Consciousness Explains Our Insatiable Search for Meaning Read Online Free Page B
the same person. But if he were a decent, professional reporter, seeking out definitive evidence like a bloodhound, his conclusions on Clark and Superman would be very different. If he studied Clark’s bizarrely frequent visits to telephone booths and knew that Superman always popped out of the very same booths moments later, if he found out that Clark always wore a Superman costume under his normal clothes, if he saw what Clark looked like without glasses, and so on—it would be blindingly obvious they were actually one and the same person.
Descartes’ argument, essentially based on his ignorance of the brain, is underpinned by a similar unwillingness to explore the evidence. To comprehensively test his claim, just as the bystander should be studying every detail of both Clark Kent and Superman, we would need to know everything about our brains and our awareness. If there are instances when consciousness radically alters, but brain activity is unchanged, then we can start talking about independence of brain and mind— but not until . As it is, all brain-scanning experiments to date have shown that even the subtlest of changes in consciousness are clearly marked by alterations in brain activity. The alternative perspective, then, that consciousness is a physical, brain-based process, is eminently more plausible than the belief that consciousness is independent of the physical world.
But Descartes also claimed that our minds are necessarily private, subjective, and unobservable by others. It’s worth lingering on this point. When I look out at the vast ocean, hear the pulsing murmur of the waves, and feel a sense of peace and contentment, no one else will ever experience precisely what I experience at that moment. In an absolute sense, it seems that I really am trapped, alone, inside my head, and there’s nothing science can do to change this. To extend Descartes’ assertion in the modern world, brain scanners may capture an approximation of my consciousness, but could they ever, even in principle, enable someone else perfectly to experience what I just experienced? This question reflects the abiding mystery of subjectivity, which remains the inspiration for modern attempts to demonstrate the independence of mind and brain.
Finally, it is worth pointing out that Descartes, like everyone else who thought about such things until a century or so ago, assumed that the mental realm simply meant everything he was conscious of. Descartes would probably have viewed the concept of unconscious thoughts as an oxymoron, and certainly would never have accepted that our unconscious minds could influence our consciousness, as we all now largely assume. For the record, whenever I use the term “mind” from now on, or discuss “mental states,” I’m including all cognitive processing, conscious or not.
Although Descartes had contemporary critics who essentially believed that the mind was the physical brain (most notably the English philosopher Thomas Hobbes), Descartes’ mind-brain duality was largely accepted, even by philosophers, for centuries.
MODERNITY ARRIVES AND GHOSTS LEAVE
Despite Descartes’ prominence, beginning in the mid-nineteenth century within the medical and fledgling neuroscience communities there was mounting evidence that a dualistic position was simply untenable. The most famous neurological case of this period was that of Phineas Gage. Gage was a foreman working in railroad construction in Vermont. One day, while he was helping to clear a volume of rock using explosives inserted into a hole, the gunpowder exploded prematurely. The tamping iron he was using shot out of the hole like a bullet. The frightening piece of metal was 3 centimeters wide, over a meter long, and weighed roughly 6 kilograms. It penetrated his left cheek, shattering the bone, then shot through his left frontal lobe, probably destroying much of the front part of the brain (see Figure 1 ). Finally it shot out through the top of
Descartes’ argument, essentially based on his ignorance of the brain, is underpinned by a similar unwillingness to explore the evidence. To comprehensively test his claim, just as the bystander should be studying every detail of both Clark Kent and Superman, we would need to know everything about our brains and our awareness. If there are instances when consciousness radically alters, but brain activity is unchanged, then we can start talking about independence of brain and mind— but not until . As it is, all brain-scanning experiments to date have shown that even the subtlest of changes in consciousness are clearly marked by alterations in brain activity. The alternative perspective, then, that consciousness is a physical, brain-based process, is eminently more plausible than the belief that consciousness is independent of the physical world.
But Descartes also claimed that our minds are necessarily private, subjective, and unobservable by others. It’s worth lingering on this point. When I look out at the vast ocean, hear the pulsing murmur of the waves, and feel a sense of peace and contentment, no one else will ever experience precisely what I experience at that moment. In an absolute sense, it seems that I really am trapped, alone, inside my head, and there’s nothing science can do to change this. To extend Descartes’ assertion in the modern world, brain scanners may capture an approximation of my consciousness, but could they ever, even in principle, enable someone else perfectly to experience what I just experienced? This question reflects the abiding mystery of subjectivity, which remains the inspiration for modern attempts to demonstrate the independence of mind and brain.
Finally, it is worth pointing out that Descartes, like everyone else who thought about such things until a century or so ago, assumed that the mental realm simply meant everything he was conscious of. Descartes would probably have viewed the concept of unconscious thoughts as an oxymoron, and certainly would never have accepted that our unconscious minds could influence our consciousness, as we all now largely assume. For the record, whenever I use the term “mind” from now on, or discuss “mental states,” I’m including all cognitive processing, conscious or not.
Although Descartes had contemporary critics who essentially believed that the mind was the physical brain (most notably the English philosopher Thomas Hobbes), Descartes’ mind-brain duality was largely accepted, even by philosophers, for centuries.
MODERNITY ARRIVES AND GHOSTS LEAVE
Despite Descartes’ prominence, beginning in the mid-nineteenth century within the medical and fledgling neuroscience communities there was mounting evidence that a dualistic position was simply untenable. The most famous neurological case of this period was that of Phineas Gage. Gage was a foreman working in railroad construction in Vermont. One day, while he was helping to clear a volume of rock using explosives inserted into a hole, the gunpowder exploded prematurely. The tamping iron he was using shot out of the hole like a bullet. The frightening piece of metal was 3 centimeters wide, over a meter long, and weighed roughly 6 kilograms. It penetrated his left cheek, shattering the bone, then shot through his left frontal lobe, probably destroying much of the front part of the brain (see Figure 1 ). Finally it shot out through the top of
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