Theories of Consciousness

The Case Against Reality

Donald Hoffman wrote The Case Against Reality - Why Evolution Hid the Truth From Our Eyes. What follows are direct quotes, in the order presented in the book, which illustrate, to me, the basic ideas presented in the book.

Chapter 1 - Mystery

The mystery of consciousness, which was the focus of the Helmholtz Club and the subject of Bogen's talk, is quite sumply7 the mystery of who we are. Your body, like other objects, has physical attributes such as position, mass and velocity. If, heaven forbid, a rock and your body fell simultaneously from the Leaning Tower of Pia, both would strike the ground at the same time.

Second, we have "propositional attitudes", such as 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.

Like a rock, we have bona fide physical properties. But unlike a rock, we have conscious experiences an propositional attitudes. Are these also physical? If so, it's not obvious. What is the mass if dizziness, the velocity of a headache, or the position of the wonder why Chris won't call? In each case, the question itself seems to harbor confusion, and to mismatch categories. Dizziness is not the kind of thing that can be weighed on a scale; a wonder has no spatial coordinates; a headache can't be clocked with a radar gun.

But conscious experiences and propositional attitudes are essential to human nature. Delete them and we lose our very selves. The bodies that remained would lumber through life pointlessly.

So, what kind of creature are you? How is your body related to your conscious experiences and propositi8nal attitudes? How is your experience of a chai latte realted to activities in your brain? Are you just a biochemical machine If so, how does your brain give rise to your conscious experiences? The question is deeply personal and, as it happens, deeply mysterious.


Note how Science asks the question: What is the biological basis of consciousness? It reveals the kind of answer that most researchers expect - that there is a biological basis for consciousness, that consciousness is somehow caused by, or arises from, or is identical to, certain kinds of biological processes. Given this assumption, the goal is to find the biological basis and describe how consciousness arises from it.

That there is a neural origin for consciousness was the working hypothesis of Francis Crick. As he put it, "The Astonishing Hypothesis is that 'You, your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact nothing more than the behavior of a vast assembly of nerve cells and their associated molecules... You're nothing but a pack of neurons.'


These are impressive applications of NCCs. Equally impressive is our utter failure to understand the relation between NCCs and consciousness. We have no scientific theories that explain how brain activity - or computer activity, or any other kind of pbhysical activity - could cause, or be, or somehow give rise to, conscious experience. We don't have even one idea that's remotely plausible. If we consider not just brain activity, but also the complex interactions among brains, bodies, and the environment, we still strike out. We're stuck. Our utter failure leads some to call this the "hard problem" of consciousness, or simply a "mystery." We know far more neuroscience than Huxley did in 1869. Yet each scientific theory that tries to conjure consciousness from the complexity of interactions among brain, body, and environment always invokes a miracle - at precisely that critical point where experience blossoms from complexity. The theories are Rube Goldberg devices that lack a critical domino and need a sneak push to complete the trick.

Chapter 3 - Reality

So what in the world is the brain computing when we look, and why?

The standard reply by neuroscientists is that the brain is constructing, in real time, our perceptions of objects such as apples and waterfalls. It constructs them because the eye itself does not see apples and waterfalls; instead, it has about 130 million photoreceptors, and each of them sees just one thi9ng: how many photons of light it just captured. ... There are, at the photoreceptors of the eye, no luscious apples and no dazzling waterfalls. There is just a stupefying array of numbers, with no obvious meaning. To endow this hill of beans with meaning, to understand what these lifeless numbers say about a living world, is such a daunting task that billions of neurons, including many millions with the eye itself, are conscripted into service. It's not like translating Greek to English. It's more like detective work: the numbers are cryptic clues, and the brain must sleuth like Sherlock. Or it's like theoretical physics: the numbers are experimental data and the brain must pull an Einstein. Which clever detective work and theorizing, your brain interprets a jumble of numbers a a coherent world, and that interpretation is what you see - the best theory your brain could muster.


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