Susan Blackmore, Consciousness: A Very Short Introduction, Oxford U. P. 2005. Chapters 1-2. [Comments in square brackets are my own thoughts.] Ch. 1: WHY THE MYSTERY? ^^^^^^^^^^^^^^^^^^^^^^^ The hard problem ~~~~~~~~~~~~~~~~ Blackmore immediately zeroes in in Chalmer's "hard problem": "How on earth can the firing of millions of tiny brain cells produce this -- my private, subjective, conscious experience?" (p.1) She then frames it in terms of the "explanatory gap" (p.2-3): Subjective experiences exist (qualia - the experience of redness when looking at a rose, a pain in the foot, etc.) Equally, there seems to be a world out there that we are part of, with trees, computers, tornadoes, etc. They seem like entirely different sorts of things from qualia. How are they connected? The historical, and popular, and religious answer (except in Buddhism): dualism, i.e., 2 different realms of existence. She remarks (p.4) that dualism is deeply embedded in our language when we say "I have a brain, body, etc.", as if there were an "I" separate from these. [I find this dubious. I also say of a tree, "It has a trunk, branches, etc.", without thereby presuming there's an "it" separate from the physical tree. Blackmore reiterates this (for me hard-to-swallow) argument several times in the book.] Descartes' (1596-1650) dualism (body-mind contact through the pineal gland) is rejected by most philosophers, who prefer "monism" (p.4) - Idealists think there's only mind - neutral monists think there's just one stuff, but not necessarily material - materialists (the majority) take matter to be fundamental All 3 have some difficult explaining to do -- again, the hard problem. The easy problems are the ones we know *in priciple* how to solve, even if we haven't done so yet. (p.5) Patricia Churchland: It's a "hornswoggle problem" (contrived problem, humbug) -- we may find the "hard" problem evaporates when we've solved the "easy" ones. [But Pinker noted that the quite brisk progress in neuroscientific consciousness research hasn't brought us an iota closer to accounting for qualia, as such.] Defining consciousness ~~~~~~~~~~~~~~~~~~~~~~ Thomas Nagel (1974): We will never understand subjectivity and qualia, because we have access only to our own; (p.6-7) "What is it like to be a bat" -- we can't know, even if we understand the bat's sensory powers. [I wonder. If we come to understand *in general* -- not just in people -- how subjective qualia arise, we may find out what it's like to be a bat, even though we'll presumably never *experience* what it's like to be a bat; even that I'm not quite sure about. On a related note: There was an article by Jacobs and Nathans, "The evolution of primate color vision" in the Scientific American, April 2009, from which I learned that while primates have 3 types of color receptors, non-primate mammals have only two. Amazingly, when mice were implanted with the monkey gene for 3 receptor types, they could discriminate blue from orange patches that are indistinguishable for normal mice. One would assume that the altered mice were thus able to experience qualia that normal mice can't. So to an extent, the mice found out "what it's like to see like a monkey!] NICE SUMMARY OF THE CENTRAL CONCEPTS AND ISSUESS, P.7: - "What it's like to be..." - subjectivity/phenomenality - qualia - the hard problem [We need to be cautious about the phrasing "what it's like", because "being like" can mean "resemble". Consider the following seemingly reasonable semi-formal version: exists x.[Being-a-bat be-like x] Isn't this trivially true for x = Being-a-bat? I.e., isn't it trivially true that being a bat is like being a bat? So in that case, there *is* something, namely being bat, which like being a bat! I prefer the less ambiguous formulation exists x,y.[x is-a-bat]&[y is-a-sensation]& [x experiences/feels y], i.e., at least *some* sensation y is experienced by some bat x. This is *not* trivially true. For example, substituting "rock" for "bat" surely renders it false or at least meaningless (being a rock doesn't FEEL like anything). Even for bats it might conceivably be false, keeping in mind that we *do* have unconscious perceptions and reflexes -- e.g., when I run, my heart rate goes up; also keep in mind seeing, acting robots, and even operating systems... Mind you, if the above is the sense in which Nagel intended his dictum, i.e., he meant "If there is something it FEELS like to be a bat, then bats are conscious", then the dictum seems rather empty, essentially rephrasing consciousness as having some feelings or sensations (i.e., experiences).] Colin McGinn: We can never know, just as a dog can never read the newspaper. [I doubt it; while there *are* Gödel-like limits to self-knowledge, I think it's too early for pessimism about consciousness.] Blackmore (p.8): at least the mysterians remind us that the job is not done when we have explained perception, memory, learning, etc. [Yes, we have to explain how experience comes about -- but our theory of course needn't, and can't, *produce* experiences. By definition, subjective experiences can't truly be shared (except, presumably, in the sense of 2 people having very similar subjective experiences; in such cases they can often be *inferred by analogy* (assuming the people find themselves in agreement when discussing their experiences in response to the same or similar stimuli, and neither have perceptual/neural deficits, or they have very similar perceptual/neural deficits).] Ned Block: "phenomenal consciousness" (related to Husserl's "phenomenology") <=> qualia; whereas "access consciousness", the basis for self-monitoring, self-knowledge, etc.) is more tractable. ASK YOURSELF (p.8): "Is consciousness an extra ingredient that ^^^^^^^^^^^^ we humans have in addition to our abilities of perceiving, thinking, and feeling [?!], or is it an intrinsic and inseparable part of being a creature that can perceive and think and feel [?!]" [I would say "sense" instead of "feel", since "feelings" already presuppose experiences/qualia!] p.9: If consciousness is extra, why do we have it? If it's not, why do we think we have it?! This leads to ... Zombies (p.10-12) ^^^^^^^ Chalmers thinks it is logically possible for there to be creatures exactly like us, but experiencing nothing. Churchland, Dennett, & Blackmore herself think this is silly. The fact that we can imagine them doesn't make them possible. Suppose it was possible, and we took away your consciousness. What would change? By definition, nothing. Given the physical basis of all your brain and motor processes, you would still claim to experience colors, pains, emotions, etc., & express your puzzlement about them. So if zombies are possible, we might as well concede we're all zombies, or in any case that zombies are indistinguishable from conscious beings. [However, I think the notion of *appearing* to be conscious, while not being conscious is not so far-fetched. Consider, for instance, a chatbot; or a remote-controlled android; or a blind person with a vision gadget, disguised as sunglasses, that whispers detailed descriptions of what's in front of him in his ears - allowing him to *pretend* he can see. Going further, a person might *almost* be a zombie, receiving only, say, verbal input, and pretending, via various gadgets that feed him descriptive information, that he is seeing things, hearing music and birds, feeling pain when somebody pokes him, etc. By the same token, it seems that we could build quite a sophisticated robot that is zombie-like, behaving in quite a sophisticated manner, and intepreting visual and acoustic input, etc., yet experiencing nothing.] Some theories out there: - consciousness is epiphenomenal (but then why are we talking about it? Why are we convinced it's important?) - consciousness is identical with certain brain states (identity theory, functionalism) - it's an illusion into which thinking, perceiving, motivated beings inevitably fall (delusionism) Blackmore plumps for the third. [I don't like any of the three; conscious experience seems like an ALTERNATIVE perspective on reality, just as valid as the third-person perspective. It's not right to say one causes the other, anymore than the gravity an astronaut trainee feels in a centrifuge is caused by the rotation of the centrifuge. From a consistent external perspective, there *is* no (radial) gravity. From the astronaut's perspective, there really *is* radial gravity -- or so Einstein's general theory of relativity says.] The theater of the mind (p.13-16) ^^^^^^^^^^^^^^^^^^^^^^^ Nice picture! The idea of an "inner observer" leads to a regress. [However, imagine a neural process that maps internal "images" (analog representations) into propositions, such as "I am looking at a red rose"; this involves no regress.] Remarks on William James' stream of consciousness Blackmore says, "I feel as though I am somewhere inside my head". [I sure don't; I feel I am all of me; I do have a *concept* of myself in my head, but we shouldn't confuse one's self-concept with oneself. I think that while one can arrive at a self-concept like Blackmore's as a result of introspection and persuasion, one can also arrive at another one, such as "I feel as though I am somewhere inside my chest" -- a notion prevalent in ancient times. It's not surprising that we can have different opinions about what exactly "I" or "me" refers to, since it's a process of *discovery* and concept-formation to relate symbols to their reference. Babies find that certain things in their intimate vicinity -- bodyparts, including their faces -- directly give rise to feelings, and that certain mental acts - "willing" -- allow control of those same things; so this collection of things becomes a possible reference of "I", by analogy with the use of "I" by humans around the baby, and their analogous parts. But the baby might arrive at other self-concepts too, thinking of its bodyparts not as part of the reference of "I", but as things "possessed" and controlled by whatever "I" refers to.] Dennett says there is no "Cartesian theater" -- no "homunculus" viewing a movie in the brain. There's no place where consciousness happens, not even a distributed place. Rather, various processes are running and compete for resources, and the most prominent at any time correspond to conscious experience. [Hardly "consciousness explained"!! He's fun to read, though. B. Baars does posit exactly a "theater of consciousness" -- a clearinghouse, or blackboard, where all processes can place information, and obtain information, to guide them further. I also think that information that relates to our self-model plays a special role in consciousness. In a way the self-concept seems to be the "hook" that supports a coherent sense of subjective experience. I also suspect, like Doug Hofstadter, Michael Arbib, and others, that the boundary between unconscious and conscious thought corresponds to the boundary between non-symbolic neural processing, and high-level symbolic/linguistic processing.] CH. 2: THE HUMAN BRAIN (p.17-) ^^^^^^^^^^^^^^^^^^^^^^ Consciousness is clearly a brain-dependent, physical phenomenon - Drugs can affect the state of consciousness - Stimulating certain brain areas causes experiences/hallucinations - Specialized areas: vision, hearing, speech, body image, motor control, planning, etc. - criss-crossing connections (no central processor) - synesthesia (p.20): e.g., may see colors or hear sound when reading or hearing numbers/shapes, etc. (V.S. Ramachandran: numbers & colors are processed in adjecent areas!) Blackmore reiterates (p.18) that we have a sense of "unified" experience, associated with "me". How brain processes lead to this needs to be explained. (p.18) Most processing is unconscious (e.g., motor control in ping pong). What makes the difference between the "conscious bits" and the unconscious ones? Neural correlates of experiences (p.20) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Pain involves C-fibers local electrochemistry ----------> spinal chord ----> brain stem ---> thalamus ---> somatosensory cortex (body map) ---> cingulate cortex. All become active. Correlation between A, B implies (p.21-22) - A caused B - B caused A - some C caused A and B - A and B are identical (e.g., morning star & evening star) [The "gravity analogy" shows that there's at least one other alternative: different perspectives on the same phenomenon! Another analogy: a child is pointing at a rainbow and smiling with pleasure. What causes her pleasure? The rainbow. But now imagine a neuroscientist in a high-flying airplane, observing the child through a powerful telescope. From the neuroscientist's perspective, there is no rainbow. The child, from that perspective, is simply reacting to photons falling on her retina that were refracted and scattered by the raindrops -- the entire reaction can in principle be described in terms of neural processes without any reference to a "rainbow". Yet there *is* a rainbow from the child's perspective -- and is that not the *cause* of her pleasure? Your homework asks you to think about this.] Blackmore objects to the identity theory -- how can the pain *be* the above activation pattern? Nikos Logothetis (1980's): binocular rivalry in monkeys -- different images (horizontal/vertical stripes) shown to the 2 eyes. Monkeys sometimes see one, sometimes the other (pressing levers accordingly). V1 activity stays the same, but temporal cortex activity varies. Likewise for humans, using brain scanning (fMRI). Ramachandran thinks these areas are qualia-laden. [I think this may be true in the sense that they are the interface between the highest level of nonsymbolic processing and conceptual processing -- i.e., *experiencing* the qualia may require formation of "mentalese" conceptualizations that incorporate percepts (in the sense of neural activation patters reflecting perceptual input) as constituents, recognizing these *as* percepts of particular types, such as visual or auditory patterns), where these conceptualizations become part of a continual self-modeling process. Note that symbolic abstraction seems to take place in the temporal lobe. Interesting articles relating to binocular rivalry, pointed out to me by former 291 student Emily Erdman, are Nikos Logothetis & Jeffrey Schall, "Neuronal correlates of subjective visual perception", Science 245, Aug. 1989, 761-763; http://sciencemag.org/cgi/reprint/245/4919/761.pdf and Andreas K. Engel, Pascal Fries, Peter König, Michael Brecht and Wolf Singer, "Temporal Binding, Binocular Rivalry, and Consciousness", Consciousness and Cognition 8(2), June 1999, 128-151. I have online copies of both. It appears that a requirement for conscious perception of an object is synchronous firing (within a millisecond) of neurons in neural assemblies corresponding to that object in the early visual pathway. The 1999 paper summarizes the evidence, and refers to Crick and Koch for this hypothesis, and also Thomas Metzinger's hypothesis of a self-model requiring synchronous neural firing.] Blackmore (p.24): but why/how does activity in some cells (but not others) lead to consciousness?? Damaged minds (p. 24-28) ^^^^^^^^^^^^^^^^^^^^^^^^ [Stephen Wright: "Right now I'm having amnesia and deja-vu at the same time. I think I've forgotten this before."] - stroke sometimes causes unilateral (hemifield) neglect; unaware of things in the right (or left) visual field; even *imagining* a familiar scene shows the neglect (Bisiach); - hippocampal damage (p.26): anterograde amnesia (can't form long-term memory; Jimmy G. thought he was 19, always. C.W. diary: "I have just become conscious again" (repeatedly!) [There was an interesting segment with Alan Alda, Sci. Am., 2009, or 2010, featuring a nice fellow who had old memories, but no new ones.] - Blindsight (p.28-32) ^^^^^^^^^^^ D.F. (visual agnosia): can't recognize forms, but grasps objects accurately; [cf robots!] she can insert envelope into a slot without awareness of orientation of either. There are 2 processing pathways from V1: ventral (lower, to temporal lobe and visual perception) and dorsal (upper, to parietal lobe - fast, visually guided action area) The ventral is too slow to guide the dorsal! [I've noticed this in riffling through e.g., a phone book to find something - I stop before I know I've found it!] D.B. (V1 damage): can "guess" direction of stripes but says he can't *see* the direction. Here the above explanation fails, because V1 is inactive; the explanation lies in other earlier visual pathways from the optic nerve to various brain areas *other than* V1. Even *emotional* response can occur in blindsight! Conclusion: our sense of a single visual experience is an illusion. [Well, in these cases of lesions, we just don't have the full integration that gives the sense of unity -- the self- modelling is out of joint with actual processing.]