miércoles, 20 de enero de 2021

Contra la realidad



CAPÍTULO I

Epilepsy

Brain Surgery.

In February of 1962, Joseph Bogen and Philip Vogel sliced in half the brain of Bill Jenkins—intentionally, methodically, and with careful premeditation. Jenkins, then in his late forties, recovered and went on to enjoy a quality of life that had eluded him for years. In the decade that followed, Bogen and Vogel split brain after brain in California, earning them the epithet “the West Coast butchers.”


When I first met Bogen in 1995, our topic of discussion was not the dramatic success of his surgery, but the exotic changes in consciousness that it triggers.


The mystery of consciousness, which was the focus of the Helmholtz Club and the subject of Bogen’s talk, is quite simply the mystery of who we are.

The mystery of consciousness is quite simply the mystery of who we are.

Your body, like other objects, has physical attributes such as position, mass, and velocity.

On the other hand, we differ from rocks in two key respects.

First, we experience sensations. We taste chocolate, suffer headaches, smell garlic, hear trumpets, see tomatoes, feel dizzy, and enjoy orgasms.

Second, we have “propositional attitudes,”

The belief that rocks don’t have headaches, the fear that stocks might fall, the wish to vacation in Tahiti, and the wonder why Chris won’t call. Such attitudes allow us to predict and interpret our behavior and that of others. If you wish to vacation in Tahiti and believe that you’ll need an airline ticket to do so, then there’s a good chance you’ll buy that ticket. Your propositional attitudes predict and explain your behavior. If Chris calls and says he’ll arrive on the train tomorrow morning at nine o’clock, then your attribution of propositional attitudes to Chris—that he wants and intends to take the train—allows you to predict where he will be tomorrow at nine, indeed with greater facility than if you knew the state of each particle of his body.

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Like a rock, we have bona fide physical properties. But unlike a rock, we have conscious experiences and propositional attitudes.

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Roger Sperry

Split of Consciousness

The “Astonishing Hypothesis” offers a cogent explanation: if consciousness arises from the interactions of a pack of neurons, then splitting that pack—and their interactions—can split consciousness.


To the untutored intuition, it seems unlikely that consciousness can be split with a scalpel. What could it mean to split my feelings, my knowledge, my emotions, my beliefs, my personality, my very self? Most of us would dismiss the idea as ludicrous. But to Sperry, after years of careful experiments, the evidence was clear: “Actually the evidence as we see it favors the view that the minor hemisphere is very conscious indeed, and further that both the separated left and the right hemispheres may be conscious simultaneously in different and even conflicting mental experiences that run along in parallel.”



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Neural correlates of conscious experience.


Activity in area V4 of the temporal lobe correlates with conscious experiences of color.




Activity in a region of the brain called the postcentral gyrus correlates with conscious experiences of touch.




Many experiments today continue the hunt for “neural correlates of consciousness” or NCCs.15 This hunt is aided by a variety of technologies for measuring neural activity. For instance, functional magnetic resonance imaging (fMRI) tracks neural activity by measuring the flow of blood in the brain: neural activity, like muscle activity, requires a greater flow of blood to supply the extra energy and oxygen that are required. Electroencephalography (EEG), using electrodes glued to the scalp, tracks neural activity by measuring tiny fluctuations of voltage that it generates. Magnetoencephalography (MEG) tracks neural activity by measuring tiny fluctuations of magnetic fields. Microelectrodes can record the individual signals, called spikes or action potentials, of single neurons and small groups of neurons. Optogenetics uses colored lights to control and monitor the activity of neurons that have been genetically engineered to respond to specific colors.




The strategy of hunting for NCCs makes sense. If we want a theory that links neurons and consciousness, and we have no plausible ideas, then we can start by looking for correlations between them. Inspecting these correlations, we might discover a pattern that turns on a conceptual lightbulb. The path from correlation to causation, to be sure, is fraught with pitfalls: if a crowd forms at a train platform, then often a train soon arrives.16 But crowds don’t impel trains to roll in. Something else—a train schedule—creates the correlation between crowds and trains.




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Many experiments today continue the hunt for “neural correlates of consciousness” or NCCs.




The strategy of hunting for NCCs makes sense. (Looking for correlations may help tp discover a pattern that turns on a conceptual lightbulb.)

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NCCs are key data for a theory of consciousness. Such a theory must perform two tasks. It must delineate the boundary between the conscious and unconscious, and it must explain the provenance and rich variety of our experiences—the taste of a lemon, the fear of spiders, the joy of discovery.




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No tenemos ni puta idea.

Misterianismo chomskyano.




We have scientific laws that predict black holes, the dynamics of quarks, and the evolution of the universe. Yet we have no clue how to formulate laws, principles, or mechanisms that predict our quotidian experiences of tasting herbs and hearing street noise.

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But before punting the hard problem of consciousness, we might consider a different possibility: perhaps we possess the necessary intelligence and are hindered by a false belief.




False beliefs, rather than innate limits, can stump our efforts to solve puzzles. Examples of this are standard fare in textbooks on cognitive science. In one example, people are given a candle, a box of thumbtacks, and a book of matches. They’re asked to fasten the candle to a wall so that, when lit, its wax can’t drip on the floor. Most people fail. They tacitly assume that the box must do one thing—hold thumbtacks. They don’t think to dump the tacks out of the box, to use the tacks to fasten the box to the wall, and to put the candle in the box. To solve the puzzle, they must challenge a false assumption.




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What false assumption bedevils our efforts to unravel the relation between brain and consciousness? I propose it is this: we see reality as it is.

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Most of us believe that, in the normal case, we accurately see SOME of reality as it is.




The core point will be that the reality prompting you to create your experience of a tomato is nothing like what you see and taste. We have been misled by our perceptions.




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Our penchant to misread our perceptions, as philosopher Ludwig Wittgenstein pointed out to his fellow philosopher Elizabeth Anscombe, stems in part from an uncritical attitude toward our perceptions, toward what we mean by “it looks as if.” Anscombe says of Wittgenstein that, “He once greeted me with the question: ‘Why do people say that it was natural to think that the sun went round the earth rather than that the earth turned on its axis?’ I replied: ‘I suppose, because it looked as if the sun went round the earth.’ ‘Well,’ he asked, ‘what would it have looked like if it had looked as if the earth turned on its axis?’ The question brought it out that I had hitherto given no relevant meaning to ‘it looks as if’ in ‘it looks as if the sun goes around the earth.’ ”25 Wittgenstein’s point is germane any time we wish to claim that reality matches or mismatches our perceptions. There is, as we shall see, a way to give precise meaning to this claim using the tools of evolutionary game theory: we can prove that if our perceptions were shaped by natural selection then they almost surely evolved to hide reality. They just report fitness.




Nuestra inclinación a interpretar mal nuestras percepciones, como señaló el filósofo Ludwig Wittgenstein a su compañera filósofa Elizabeth Anscombe, se deriva en parte de una actitud acrítica hacia nuestras percepciones, hacia lo que queremos decir con "parece como si". Anscombe dice de Wittgenstein que, “Una vez me saludó con la pregunta: '¿Por qué la gente dice que era natural pensar que el sol giraba alrededor de la tierra en lugar de que la tierra giraba sobre su eje?' Yo respondí: 'Supongo , porque parecía como si el sol girara alrededor de la tierra ''. `` Bueno '', preguntó, `` ¿cómo se habría visto si la tierra hubiera girado sobre su eje? ''. La pregunta hizo que saliera a la luz que yo hasta el momento no le había dado un significado relevante a 'parece como si' en 'parece como si el sol girara alrededor de la tierra'. El punto de Wittgenstein es relevante cada vez que deseamos afirmar que la realidad coincide o no coincide con nuestras percepciones. Existe una manera de dar un significado preciso a esta afirmación utilizando las herramientas de la teoría de juegos evolutiva: podemos probar que si nuestras percepciones fueron moldeadas por selección natural, entonces es casi seguro que evolucionaron para ocultar la realidad. Solo indican aptitud.

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THE TOMATO IS NOT THERE

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evolution by natural selection entails a counterintuitive theorem: the probability is zero that we see reality as it is. This theorem applies not just to taste, odor, and color, but also to shape, position, mass, and velocity—even to space and time. We see none of reality as it is. The reality that prompts you to create an experience of a tomato, the reality that exists whether or not you see a tomato, is nothing like what you see and taste.




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This theorem applies even to space and time.

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We discarded a flat earth and a geocentric universe. We realized that we had misread our perceptions, and we corrected our errors. It wasn’t easy. In the process, mundane intuitions and Church doctrines were shattered. But these corrections were mere warm-ups. Now we must jettison spacetime itself, and everything in it.







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Understanding the evolution of perception.
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CAPÍTULO II