Weisberg et al. (2008) presented subjects with two explanations for psychological phenomena (e.g. attentional blink). Some subjects got the regular explanation, and other subjects got the 'with neuroscience' explanation that included purposely irrelevant verbiage saying that "brain scans indicate" some part of the brain already known to be involved in that psychological process caused the process to occur.
And yet, Yale cognitive science students rated the 'with neuroscience' explanations as more satisfying than the regular explanations.
Why? The purposely irrelevant neuroscience verbiage could only be important to the explanation if somebody thought that perhaps it's not the brain that was producing certain psychological phenomena. But these are Yale cognitive science students. Somehow I suspect people who chose to study cognition as information processing are less likely than average to believe the mind runs on magic. But then, why would they be additionally persuaded by information suggesting only that the brain causes psychological phenomena?
In another study, McCabe & Castel (2008) showed subjects fictional articles summarizing scientific results and including either no image, a brain scan image, or a bar graph. Subjects were asked to rate the soundness of scientific reasoning in the article, and they gave the highest ratings when the article included a brain scan image. But why should this be?
I remember talking to a friend about free will. She was a long-time physicalist who liked reading about physics and neuroscience for fun, but she didn't read Less Wrong and she thought she had contra-causal (libertarian) free will.
"Okay," I said. "So the brain is made of atoms, and atoms move according to deterministic physical law, right?"
"Right," she said.
"Okay. Now, think about the physical state of the entire universe one moment before you decided to say "Right" instead of something else, or instead of just nodding your head. If all those atoms, including the atoms in your brain, have to move to their next spot according to physical law, then could you have said anything else than what you did say in the next moment?" (Neither of us understood many-worlds yet, so you can assume we're talking about a single Everett branch.)
She paused. "Huh. I'll have to think about that."
"Also, have you heard about those studies where brain scans told researchers what the subjects were going to do before the subjects consciously decided what they were going to do?"
"No! Are you serious?"
"Yup. Sometimes they could predict the subject's choice 10 seconds before the subject consciously 'made' the choice."
"10 seconds? Wow. I didn't know that."
I think that maybe the 'with neuroscience' explanations and brain scan images are more satisfying partly because they remind us we're physicalists. They remind us that reductionism marches on, that psychology is produced by physical neurons we can take pictures of.
Just like most people, physicalists walk around all day with the subjective experience of a 'unity of consciousness' and contra-causal free will and so on. If a physicalist isn't a researcher who studies all the latest successful reductions in neuroscience or biology or physics all week long, and doesn't read Less Wrong every day, then it's possible to get lost in the feel of everyday experience and thus be surprised by a headline like 'Brain Scanners Can See Your Decisions Before You Make Them.'
Sometimes even physicalists need to be reminded — with concrete reductionistic details — that they are physicalists. Otherwise their normal human anti-reductionistic intuitions may creep back in of their own accord. That's one reason it helps to study many sciences, so you have many successful reductions in your head, and see (at some resolution) the entire picture, from psychology to atoms. As Eliezer wrote:
Study many sciences and absorb their power as your own. Each field that you consume makes you larger. If you swallow enough sciences the gaps between them will diminish and your knowledge will become a unified whole.
To her credit, my friend no longer believes in contra-causal free will.
I feel a bit like I'm Eliezer expaining the instant failure modes of most AGI research (but not as smart), and that there could be a whole sequence of postings on the instant failure modes of explanations of consciousness.
Well, I don't think I can write those postings, or at least, devote the many days it would take me. Just some brief notes here amplifying the fallacies with examples.
A partial and unfinished explanation. But it must go some distance: it must suggest practical experiments and predict their results. (Thought experiments do not count.) Consider the four different fallacies I described by this standard:
Empty labels: saying consciousness is "the soul", "a spark of the divine within us", "self-awareness", etc. fails to constrain expectations.
Denying the existence of subjective experience: well, we do have it. At least, I do, and I've no reason to suppose I'm exceptional in this. (Those who seriously deny it might be exceptions in the other direction.) So this one has the virtue of constraining expectations but is instantly refuted by observation. It amounts to sticking one's fingers in one's ears and going "la la la can't hear you!" Arguments against the existence of subjective experience (consciousness, qualia, etc.) generally take the form of arguing against other people's arguments in favour. Since no-one has a good account of what it is, it is not difficult to demolish their bad accounts. This is like refuting the phlogiston theory to prove that fire does not exist.
In the p-zombie category is Minsky's "society of mind", which gives a hypothetical account of how a system might come to talk to itself about itself in the ways that we do. But how we talk about ourselves and how we feel about ourselves are two different things, and the latter is left unaddressed. Besides, there are plenty of computer systems that talk to themselves about themselves, and we see no reason to attribute consciousness to them. In the form in which Greg Egan expressed the theory in his story "Mr. Volition", consciousness is the piece of brain that does consciousness, just as the cerebellum is the piece of brain that does motor control. This is no better than any other homunculus theory: it is either passing the buck or asserting that we are all philosophical zombies, beings that talk about consciousness without having it.
Physical correlates: Neuroscience is always finding more and more physical correlates of mental phenomena, from the fact that gross lesions to various brain locations produce predictable patterns of cognitive impairment, to the results of live brain imaging during task performance. This is compelling evidence that the brain must be either the physical substrate of consciousness or an interface with something else. Neither alternative goes very far. We still don't know how the brain or anything else made of atoms could be a physical substrate for consciousness, however compelling the evidence that it is. Contrast this with the fact that we do know how ever-so-slightly impure silicon can be a substrate for computation. And the brain as an interface to something else fares even worse, as we have no idea what that something else could be. The soul? See (1).
So those are four basic ways in which attempts to explain consciousness can go wrong. I have yet to see an attempt that doesn't fail one or more.
The comments of yours I've read are always clear and insightful, and usually I agree with what you say. I have to disagree with you here, though, about your supposed second fallacy.
I disagree. Arguments against qual... (read more)