Nautilus magazine is one of those slick "science information" sites where we sometimes get real science and other times get various assorted stuff that is not really science in the sense of being facts. In the latest version of the online magazine, we have an interview with neuroscientist David Eagleman. The interview is found under the ludicrous title "Your Brain Makes You a Different Person Every Day." While it is true that the proteins in the brain have such short lifetimes that an estimated 3% to 4% of your brain proteins are replaced every day, it is false that you are a different person every day. The persistence and stability of an individual's personality, memory and identity despite such heavy turnover of brain proteins is one of many good reasons for thinking that your mind and memory are not brain effects. If your brain was the source of your personhood, then given rapid brain protein turnover, you might then be a "different person every day." But it is not that, and you are not that.
In the interview, Eagleman claims, "When you learned that my name is David, there’s a physical change in the structure of your brain." There is no evidence of such a thing. The claimed evidence (mainly from badly-designed mouse experiments) has a variety of flaws which makes it far less than robust evidence. No one has ever found a stored memory by examining tissue in a human brain. If the creation of a memory required "a physical change in the structure of the brain," then you could never instantly form a memory. But humans can instantly form permanent new memories. If someone suddenly sticks a gun in your mouth, you will instantly form a new memory that you will remember the rest of your life.
Eagleman states, "The brain builds an internal model of the world so it can predict what’s going to happen next." There is no real evidence that such a thing happens in a brain, and no one has ever found any such thing in a brain. No neuroscientist can give a coherent and convincing explanation of how a brain could either produce thoughts or predictions.
Strangely, Eagleman seems to speak as if neurons are fighting each other inside our brains. He refers to "this aggressive background of neurons fighting against one another." Funny, I can't remember the last time I felt like I was of "two minds" about anything. In a similar dubious vein of military speculation, Eagleman then says, "my student Don Vaughn and I worked out a model showing that dreaming appears to be a way of keeping the visual cortex defended every night." That sounds like one of the least plausible theories of dreaming I have ever heard. Instead of fighting with each other, the cells in the human body show a glorious harmony in their interactions, displaying teamwork more impressive than that of a symphony orchestra or the construction crew of a skyscraper.
Commendably, the interviewer asks a good question by asking Eagleman about hemispherectomy patients who show little cognitive damage from the removal of half of their brains. Eagleman offers no explanation for why this would occur if the kind of dogmas he teaches are true, other than the very weak statement that "what this means is that half the real estate disappears and yet the whole system figures out how to function."
The interviewer then commendably says, "There is a backlash to this idea that everything in the mind is reducible to brain science," and asks Eagleman about that. Eagleman states very incorrectly "that critique has no basis at all." To the contrary, it has a mountainously large basis, consisting of things like the huge amount of evidence discussed in the posts on this site, very much of which consists of papers authored by neuroscientists themselves. Speaking briefly like a true-believer dogmatist, Eagleman says, "there's no doubt about this idea that you are your brain," but offers no real support for this claim other than making in the next sentence the strange claim that "Every single thing that happens in your life—your history, who you become, what you’ve seen—is stored in your brain."
That is a claim that in the human brain there is a record of every single thing a human has experienced, a claim that very few neuroscientists have made. If such a thing were true, it would not at all prove that "you are your brain," since your identity and self-hood and personality are a different thing than your memory. Since neuroscientists have no credible theory of either memory encoding or long-term memory storage, given a brain that replaces its proteins at a rate of about 3% per day, the more that humans remember and the longer that humans can remember, the less credible is the theory that memories are stored in brains. So Eagleman is not helping his case at all by making the strange claim that the brain stores every experience a person has ever had. If people did retain memories of every thing they had ever experienced, it would be all the more harder to explain how that could possibly occur in a brain subject to such rapid turnover and replacement of its proteins.
Eagleman offers one other little item trying to support his "you are your brain" claim, but it's paltry. He points out a neurotransmitter called dopamine can affect gambling behavior. But, of course, that does nothing to show that you are your brain. When I had a very bad toothache long ago, it sure affected by behavior, but that didn't show that I am my teeth. And if you sprained your ankle, it would briefly affect your behavior, but it wouldn't show you are your foot.
Asked about whether "one day we’ll be able to map all the neural connections in someone’s brain and know what kind of person that is," Eagleman says this will never happen in our lifetimes, but "maybe in 300 years, you could read out somebody’s brain." But if a person believes that the brain stores memories and beliefs, he should be confident that such a thing will soon happen. If brains stored memories and beliefs, we actually should have been able to read such memories and beliefs decades ago, about the time people were first reading DNA from cells. Maybe somewhere in the back of Eagleman's mind, he knows that neuroscientists are making zero progress in reading memories and beliefs from brains, and that is what caused his pessimistic estimate.
Towards the end of the interview, Eagleman begins to contradict what he said earlier with such self-assurance. He states, "It appears that consciousness arises from the brain, but there is still a possibility of something else." When the interviewer commendably follows up on this by saying, "perhaps not everything is generated by the brain" and "we might be tuning in to consciousness somewhere else," Eagleman answers by saying, "I’m not suggesting this is the case, but I am saying this is still a possibility in neuroscience that we have to consider."
So Eagleman ends up contradicting his previous claim that "there's no doubt about this idea that you are your brain." After speaking like some supremely convinced dogmatist, he now seems to have lost his certitude, and seems to doubt his previous metaphysical claim that he said there was no doubt about. He ends by saying this regarding a theory of consciousness: "Not only do we not have a good theory, we don’t even know what a good theory would look like." But such a thought clashes with his claim that "there's no doubt about this idea that you are your brain."
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