Michael Graziano: Are We Really Conscious?

He raises the question in the New York Times Sunday Review:

I believe a major change in our perspective on consciousness may be necessary, a shift from a credulous and egocentric viewpoint to a skeptical and slightly disconcerting one: namely, that we don’t actually have inner feelings in the way most of us think we do…

How does the brain go beyond processing information to become subjectively aware of information? The answer is: It doesn’t. The brain has arrived at a conclusion that is not correct. When we introspect and seem to find that ghostly thing — awareness, consciousness, the way green looks or pain feels — our cognitive machinery is accessing internal models and those models are providing information that is wrong…

You might object that this is a paradox. If awareness is an erroneous impression, isn’t it still an impression? And isn’t an impression a form of awareness?

But the argument here is that there is no subjective impression; there is only information in a data-processing device. When we look at a red apple, the brain computes information about color. It also computes information about the self and about a (physically incoherent) property of subjective experience. The brain’s cognitive machinery accesses that interlinked information and derives several conclusions: There is a self, a me; there is a red thing nearby; there is such a thing as subjective experience; and I have an experience of that red thing. Cognition is captive to those internal models. Such a brain would inescapably conclude it has subjective experience.

I agree that our intuitions about consciousness are likely to be faulty, but I don’t think that Graziano has resolved the paradox he mentions. My brain models other people as having subjective experiences, but this obviously has no bearing on whether they really do, or don’t, have those experiences. Given that, why should the fact that my brain models me as having subjective experiences suddenly become magically relevant to the question of whether I really do, or don’t, have those experiences?

317 thoughts on “Michael Graziano: Are We Really Conscious?

  1. petrushka: I’ve had several major surgeries and have not taken the prescribed pain pills. They upset my stomach and do nothing for the pain.

    But pain and dread reinforce each other. that’s why doctors are supposed to develop a good bedside manner. It works.

    I should say the book is more about growing old and dealing with physical and mental deterioration in oneself and in someone else in one’s family. The theme is: “we want autonomy for ourselves but safety for others in our family”. Can those two conflicting needs by reconciled somehow?

  2. Here is a recent podcast from Philosophy Bites which seems a propos:
    The Hard Problem and the Illusion of Qualia

    Its about 15 minutes (10 minutes at 1.5 speed!).

    I agree with the overall ideas of the speaker as I understand them, in particular how he uses the word “illusion”. But I am not going to discuss what I think they are!

  3. Bruce:

    If it is off to the side, don’t you worry that would let in the modal worlds type arguments about there being philosophical zombies and hence that qualia disprove physicalism.

    In other words, if it is off to the side, it seems quite easy to have metaphysically possible worlds where everything stays the same but there is no subjectivity.

    Well, I suppose that zombies might be metaphysically possible in some worlds, but if so, I don’t see that it would necessarily threaten physicalism in this world.

    A different problem with epiphenomenonality would be that (the subjective experience which is) awareness has no role in human agency.

    Yes. I addressed that earlier in the thread:

    An epiphenomalist like me has to acknowledge that causality is restricted to the underlying physical system, and that phenomenal experiences themselves are causally inert. So when we report a phenomenal experience, the phenomenal experience itself is not causally relevant to the report!

    This is a somewhat awkward position, but it’s not untenable if phenomenal experience reflects the state of its physical substrate in the right way. However, I’m not fully satisfied with it either, which is why I find theories like Graziano’s so fascinating.

  4. petrushka,

    I would say that if subjectivity must be off to the side, then one’s description of physical process is incomplete.

    Why?

    Wouldn’t it be more parsimonious to say I don’t know how it works?

    I do say that I don’t know how it works, but that’s orthogonal to the parsimony question, which applies to theories, not declarations of ignorance.

    Epiphenomenalism is my best candidate at the moment, but I’m not satisfied with it, as I explained above.

  5. If you are a reductionist, a complete theory of physics must account for consciousness and awareness. The problem can be put aside as unsolvable, but that would be an admission of incompleteness.

  6. keiths:

    Well, I suppose that zombies might be metaphysically possible in some worlds, but if so, I don’t see that it would necessarily threaten physicalism in this world.

    Keith:
    I think the usual argument is that if zombies are metaphysically possible when the physical state is held constant, then qualia might include non-physical elements.
    Whether they do in this world could then become a scientific issue, depending on whether you take that argument or some kind of physicalism to have priority in your worldview.

    Rather than fight that battle, I think it is better to find ways to deny zombies as even a metaphysical possibility.

    BTW, I don’t say epiphenomenonalism by itself makes the zombie argument possible; one can always insist (as I suspect you do) that even if qualia are epiphenomenal, they still must supervene solely on physical states.

    I am just saying that by having separate side paths, you have more things to justify and explain..

  7. The expression “metaphysically possible in some worlds” is a contradiction in terms. It’s nonsense.

  8. petrushka,

    If you are a reductionist, a complete theory of physics must account for consciousness and awareness.

    Right, but my question is why you think that

    …if subjectivity must be off to the side, then one’s description of physical process is incomplete.

    Are you perhaps misinterpeting “off to the side” as “not addressed by the theory”? That isn’t what I meant at all. Here’s my statement:

    No, because I don’t see subjective experience as part of the causal chain. I see it as being off to the side but linked very tightly with, and correlated to, its physical substrate.

    In other words, the physical substrate determines the subjective experience, but the subjective experience itself has no causal power. That’s what it means to say that subjective experience is epiphenomenal.

  9. Bruce,

    I think the usual argument is that if zombies are metaphysically possible when the physical state is held constant, then qualia might include non-physical elements.

    Whether they do in this world could then become a scientific issue, depending on whether you take that argument or some kind of physicalism to have priority in your worldview.

    The scientific evidence seems pretty clear: subjective experience either is physical or else is determined by the physical (as in Chalmers’s property dualism). The latter is far closer to physicalism than it is to traditional substance dualism with its gods and souls.

    It’s really just a question of what gets included in the bubble labeled “the physical”. If matter has an undiscovered property that brings about subjective awareness, as Chalmers thinks, should we consider that a physical property? I honestly don’t see that it makes much of a difference, as long as we’re clear about what we mean.

    Rather than fight that battle, I think it is better to find ways to deny zombies as even a metaphysical possibility.

    I don’t see how that’s possible, but another way to avoid the battle is to accept that we are all zombies, as Dennett and Graziano do.

    BTW, I don’t say epiphenomenonalism by itself makes the zombie argument possible; one can always insist (as I suspect you do) that even if qualia are epiphenomenal, they still must supervene solely on physical states.

    Yes, that’s my position.

    I am just saying that by having separate side paths, you have more things to justify and explain.

    Right. Hence the dilemma I expressed earlier:

    The dilemma is that epiphenomenality is obviously less parsimonious than a Dennett/Graziano-style explanation, so I would prefer to jettison it if I could; but on the other hand, the D/G explanation isn’t fully satisfying as an explanation for subjectivity, so I hang onto the epiphenomenality.

  10. I really don’t see any usefulness or explanatory power in ideas called zombies or qualia. Can someone explain, as if to a six-year-old, why they think either are meaningful?

  11. Alan Fox:
    I really don’t see any usefulness or explanatory power in ideas called zombies or qualia. Can someone explain, as if to a six-year-old, why they think either are meaningful?

    This from SEP may help, but probably not a six year old:

    A good way to make the apparent threat to physicalism clear is by adapting a thought of Saul Kripke’s (1972/80, pp. 153f.). Imagine God creating the world and deciding to bring into existence the whole of the physical universe according to a full specification P in purely physical terms. P describes such things as the distribution and states of elementary particles throughout space and time, together with the laws governing their behavior. Now, having created a purely physical universe according to this specification, did God have to do something further in order to provide for consciousness? Answering yes to this question implies there is more to consciousness than the purely physical facts can supply. If nothing else, it implies that consciousness requires nonphysical properties in the strong sense that such properties would not exist in a purely physical world: it would be a zombie world.

    The zombie world descriptions try to encourage you to answer “yes” to the question Kripke posed. If zombies could exist, then God could have created a world of zombies without changing anything physical, therefore qualia might/must add something non-physical.

  12. I don’t buy Graziano’s argument. When I accept that I have a brain (which is required for Graziano’s argument to work), it’s already presupposed that I am conscious to be able to perceive the brain and accept its existence. Any way you look at it, consciousness seems primary and the brain secondary.

  13. BruceS: This from SEP may help, but probably not a six year old:

    The zombie world descriptions try to encourage you to answer “yes” to the question Kripke posed.If zombies could exist, then God could have created a world of zombies without changing anything physical, therefore qualia might/must add something non-physical.

    Nice job. My only complaint involves the use of the term “qualia.” A number of philosophers countenance experience, subjectivity, etc., but eschew qualia. Whether or not that can be done without loss is controversial, but I think it’s important to distinguish the question “Is there consciousness?” (which, as I’ve said, seems really silly to me) from the question “Are there qualia?”

  14. BruceS: The zombie world descriptions try to encourage you to answer “yes” to the question Kripke posed. If zombies could exist, then God could have created a world of zombies without changing anything physical, therefore qualia might/must add something non-physical.

    Right;

    So the only point of imagining a “philosophical zombie” is to argue for a dualistic explanation for consciousness. It seems a religious argument. We are far from grasping the physical aspects of consciousness (or awareness) so why on Earth do we need to bring in unentailed, imaginary concepts?

  15. walto: A number of philosophers countenance experience, subjectivity, etc., but eschew qualia. Whether or not that can be done without loss is controversial, but I think it’s important to distinguish the question “Is there consciousness?” (which, as I’ve said, seems really silly to me) from the question “Are there qualia?”

    I agree that it is silly for anyone to suggest humans and other animals are not aware (or conscious). Are you agreeing that “qualia” are concepts without content?

  16. Alan Fox: I agree that it is silly for anyone to suggest humans and other animals are not aware (or conscious). Are you agreeing that “qualia” are concepts without content?

    I’m just saying that it’s possible to take the position that there is consciousness without countenancing “qualia.” For example, one could hold that experiences don’t have an objects that have all the qualities that qualia are often claimed to have–including (but not limited to) transience, incorrigibility, ineffability. Some people claim that when we experience red things, we are experiencing (correctly or incorrectly) properties of physical objects in the world. So there are “seeming reds” without there being any “quality of experience” that is red* (where “red*” denotes some kind of a transient characteristic of experience that is exemplified, not in the physical world, but in the world of consciousness).

    Forgetting about the details, my point is that the existence of qualia is controversial, the existence of consciousness is not.

  17. walto:
    The expression “metaphysically possible in some worlds” is a contradiction in terms.It’s nonsense.

    Is it a contradiction or just redundant? More specifically, my understanding is this:

    1. logically possible: no logical contradiction in the concept

    2. metaphysically possible: exists in some possible world.

    3. nomologically possible: exists in possible worlds with same scientific laws as ours.

    4. possible in our world.

    Is that close?

    There seems to be a lot of discussion about whether these four are distinct and which implies which.

    Often the issue of a priori versus a posteriori physicalism gets thrown in, which I have to go back and try to re-understand every time it comes up in something else I am trying to work through. But leave that issue out for now.

  18. walto: qualia are often claimed to have–including (but not limited to) transience, incorrigibility, ineffability.

    There are less extreme definitions of qualia; for those who prefer to avoid clicking, here are the relevant paragraphs:

    In the case of visual experiences, for example, it is frequently supposed that there is a range of visual qualia, where these are taken to be intrinsic features of visual experiences that (a) are accessible to introspection, (b) can vary without any variation in the representational contents of the experiences, (c) are mental counterparts to some directly visible properties of objects (e.g., color), and (d) are the sole determinants of the phenomenal character of the experiences. This usage of ‘qualia’ has become perhaps the most common one in recent years. Philosophers who hold or have held that there are qualia, in this sense of the term, include, for example, Nagel (1974), Peacocke (1983) and Block (1990).

    (4) Qualia as intrinsic, nonphysical, ineffable properties. Some philosophers (e.g, Dennett 1987, 1991) use the term ‘qualia’ in a still more restricted way so that qualia are intrinsic properties of experiences that are also ineffable, nonphysical, and ‘given’ to their subjects incorrigibly (without the possibility of error). Philosophers who deny that there are qualia sometimes have in mind qualia as the term is used in this more restricted sense (or a similar one).

  19. From Wiki on qualia

    Dennett’s argument revolves around the central objection that, for qualia to be taken seriously as a component of experience—for them to even make sense as a discrete concept—it must be possible to show that

    a) it is possible to know that a change in qualia has occurred, as opposed to a change in something else; or that
    b) there is a difference between having a change in qualia and not having one.
    Dennett attempts to show that we cannot satisfy (a) either through introspection or through observation, and that qualia’s very definition undermines its chances of satisfying (b).

    Is this a fair summary of Dennett?

  20. walto: Forgetting about the details, my point is that the existence of qualia is controversial, the existence of consciousness is not.

    Am I conscious when I am asleep and dreaming. I certainly “think” I am.

    Most dream stuff disappears within a few minutes of waking up, but I have some fairly vivid and persistent visual memories of dream stuff.

  21. And Rationalwiki on p-zombies:

    The usual objection to p-zombies as an argument for dualism is that the concept does not make sense without assuming dualism in the first place, thus the idea is begging the question. Effectively, it is saying that a p-zombie is exactly identical to a human except that it lacks a soul – therefore the soul exists. Such an argument is not logically valid, as it doesn’t deduce new information. It does form an interesting enough thought experiment, though, where you can ask how you’d tell them apart from “real” humans, eventually extending to how you can tell that you, yes you, aren’t a p-zombie at all. Indeed, if there is no answer, then the soul is unfalsifiable by the limits imposed on it by this thought experiment itself and so doesn’t exist or have any bearing on our lives in any meaningful way – belief in it wouldn’t even be trivial. If, on the other hand, an observable difference was proposed, the soul would cease to be supernatural, and again, the thought experiment that set out to prove the soul exists in fact disproves it, or at least certain attributes of it.; The other objection is against the conceptual existence of p-zombies, as thinking you can conceive of something doesn’t mean the universe gives a shit. Religious apologists have tried that one already. It has also been pointed out that the arguments in favor of p-zombies are eerily similar to those used in order to justify slavery and oppression in eras past. In the future the philosophical zombie argument could be uncritically applied to any robot even if one would otherwise have to conclude it was even more intelligent, sentient, and conscious than your typical human.

    Is it fair to suggest p-zombies only make sense to dualists?

  22. BruceS: There are less extreme definitions of qualia; for those who prefer to avoid clicking, here are the relevant paragraphs:

    There are, indeed, a ton of definitions. It’s a veritable industry. Without a definition, it’s nearly impossible to figure out what people are talking about when they use the term. And even then….

    Dennett has been accused of using it many ways in adjacent paragraphs.

  23. BruceS,

    But that seems to prove my point: that there are perfectly good ways to talk about consciousness, awareness and perception without introducing a term that has no consensual definition.

  24. Alan Fox:
    From Wiki on qualia

    Is this a fair summary of Dennett?

    I don’t think Dennett denies subjective consciousness (else why would he argue so strongly against “the zombie hunch”).

    I think he says that anything you call qualia must be subject to scientific study. It can use first person reports, but only as raw data. He calls this his heterophenomelogical approach, but admits this is just a fancy name for how science is done today.

    At one point he says should work in this order (paraphrased from IP p. 344)
    1. utterances of some sort that can be interpreted to express verbal judgements (most raw data)
    2. those verbal judgements
    3. beliefs about conscious experiences
    4. the conscious experiences themselves (least raw)

    He says we should be careful about saying much about 4 until we have a scientific theory.

  25. Alan Fox:
    BruceS,

    But that seems to prove my point: that there are perfectly good ways to talk about consciousness, awareness and perception without introducing a term that has no consensual definition.

    Yes, I agree that is Dennett’s point. You can ignore qualia, but you’ll have trouble if you want to engage with the philosophical literature. Most philosophers seem to ignore Dennett, not qualia.

  26. walto,

    BruceS: Is it a contradiction or just redundant?More specifically, my understanding is this:

    1.logically possible:no logical contradiction in the concept

    2.metaphysically possible:exists in some possible world.

    3.nomologically possible:exists inpossible worlds with same scientific laws as ours.

    4.possible in our world.

    Is that close?

    There seems to be a lot of discussion about whether these four are distinct and which implies which.

    Often the issue of a priori versus a posteriori physicalism gets thrown in, which I have to go back and try to re-understand every time it comes up in something else I am trying to work through.But leave that issue out for now.

    I don’t know what your( 4) meansm the rest seems fine. It doesn’t make sense to talk of something being metaphysically possible in SOME worlds, if that is supposed to suggest NOT ALL. It doesn’t even maka ton of sense to say that something is metaphysically possible in ALL worlds. It just suggests confusion.

  27. Alan Fox:
    And Rationalwiki on p-zombies:

    Is it fair to suggest p-zombies only make sense to dualists?

    As long as you include property dualist, not just substance dualist.

    And you could also say garden variety physicalism (ie excluding panpsychism) only makes sense if p-zombies don’t make sense (ie cannot exist one of the ways in my previous most on conceptual/metaphysical/nomological/this world, with controversy about which matter and which don’t).

  28. walto:
    walto,

    I don’t know what your( 4) meansm

    Sorry 4 was wrongly worded. I was trying to say simply “exists in our actual world.” The “possible” key on my keyboard got stuck, possibly.

    I see I used “metaphysically possible” at one point, although I am not sure if I added the phrase “in some worlds” in some other comment. In any event, thanks for the feedback.

  29. Erik:
    I don’t buy Graziano’s argument. When I accept that I have a brain (which is required for Graziano’s argument to work), it’s already presupposed that I am conscious to be able to perceive the brain and accept its existence. Any way you look at it, consciousness seems primary and the brain secondary.

    I think the more interesting arguments revolve around these (separate issues):
    1. Is just a living, uninjured, awake physical brain enough? Or do I need:
    2 . a body as well as 1
    3. engagement for the world by perceiving and acting as well as 1 and 2.

    4. Are 1-3 sufficient, even if not all are necessary? Or is something non-physical involved as well.

    Which came first, the brain or the consciousness to describe it, seems to be better addressed to chickens and their eggs. It depends on how primitive some grouping of neurons has to be before they quality as a brain, I suspect.

    ETA: Err, in my haste to get the the joke about chickens and eggs, I seem to have left out something:

    3.5 For whatever combination of 1-3 you think are necessary, what is the scientific explanation of how the structure and operations of these elements produces consciousness?

  30. Alan Fox:
    BruceS,
    Graziano writes:

    Make sense?

    Well, I don’t want to discuss what “makes sense” in Graziano because that involves interpreting Graziano, and in the end that was not constructive for me in this thread.

    But I do note that the above involves Dennett’s definition of qualia, and I agree that definition is wrong for the scientifically-minded.

    By the way, awareness would seem to be a blanket term covering seeing, hearing, smelling, touching, body position, taste, at least. But these are different subjective experiences, at least to me and I think most of us. One use of “qualia” is to recognize that type of difference.

  31. keiths:

    Yes.I addressed that earlier in the thread:

    Keith:
    I’m not sure if you also had in mind this, so I’ll state explicitly: it is hard to see how epiphenomenal, physical implementations would survive evolution since they seem to involve metabolic cost with no positive impact on fitness (since they have no causal impact at all).

  32. BruceS:

    I see I used “metaphysically possible” at one point, although I am not sure if I added the phrase “in some worlds” in some other comment.

    The “metaphysically possible in some worlds” was keiths’ mess, I think.

  33. Bruce,

    You’re right. It’s redundant, but not contradictory, and in any case you understood exactly what I meant.

    Walto is in a pretty desperate search for errors on my part, whether relevant to the conversation or not.

    Walto,

    Here’s a hint: Look for places where I’ve incorrectly used the indicative instead of the subjunctive. Despite my mother’s best efforts to train her children properly, I still mess this up from time to time.

  34. Alan Fox: Make sense?

    No, it doesn’t.

    I’m particularly commenting on:

    …, suggesting that the concept of qualia, …, is incoherent and thus we cannot truly have them.

    If the concept is incoherent, then talk about whether we can or cannot have them doesn’t actually make sense.

  35. Alan,

    But that seems to prove my point: that there are perfectly good ways to talk about consciousness, awareness and perception without introducing a term [“qualia”] that has no consensual definition.

    Consciousness itself has no consensual definition, but we still talk (and talk, and talk) about it — and for good reason.

    The term “quale” is important in discussions of consciousness for the same reason that the term “soul” is important in discussions of the mind/body problem. Both are intuitively appealing concepts that are widely accepted, so it is important to establish whether or not they are correct.

  36. Neil, to Alan:

    If the concept is incoherent, then talk about whether we can or cannot have them doesn’t actually make sense.

    Sure it does. I don’t have a friend who is taller than Michael Jordan and shorter than Peter Dinklage.

  37. Erik: Is this a question.

    Apparently not something that philosophy wants to deal with.

    How do you discuss what appears to be complete conscious awareness that is divorced from perception?

    From a philosopher’s perspective, how would you tell if you are in a dream?

    I ponder my dreams pretty much every day, and I can’t recall ever thinking I’m in dream while I’m in dream.

  38. keiths:
    Bruce,

    You’re right.It’s redundant, but not contradictory, and in any case you understood exactly what I meant.

    Walto is in a pretty desperate search for errors on my part, whether relevant to the conversation or not.

    Walto,

    Here’s a hint:Look for places where I’ve incorrectly used the indicative instead of the subjunctive.Despite my mother’s best efforts to train her children properly, I still mess this up from time to time.

    It’s not actually redundant–it’s confused.

    To say that some state of affairs P is metaphysically possible is to say (according to the “worlds” picture) that P obtains in at least one world. It doesn’t make sense to say that in some worlds there is a world in which P obtains.

  39. keiths: Sure it does. I don’t have a friend who is taller than Michael Jordan and shorter than Peter Dinklage.

    That post is also is also confused: it’s entirely non-responsive to Neil’s point.

    ETA: Just to add why I think that. I’m guessing that Neil would not say that being taller than Jordan and shorter than Dinklage is incoherent, though it may be impossible. That is, we know what it means–in fact, that’s how we know it’s impossible.

  40. Bruce,

    I’m not sure if you also had in mind this, so I’ll state explicitly: it is hard to see how epiphenomenal, physical implementations would survive evolution since they seem to involve metabolic cost with no positive impact on fitness (since they have no causal impact at all).

    You’re assuming that an epiphenomenal implementation would incur an additional metabolic cost over a behaviorally identical “zombic” implementation, but that isn’t necessarily true. It might turn out that being a zombie is more expensive!

    It’s also possible that epiphenomena inevitably accompany a physical implementation having the specified behavioral characteristics.

    In the book, Graziano keeps returning to what he calls “Arrow B” — the arrow by which our awareness has causal effects. He is correct that epiphenomena are causally inert, and that arrow B therefore cannot emanate from them. What he overlooks is that Arrow B can still emanate from the physical substrate that gives rise to the epiphenomena.

  41. keiths:
    Bruce,

    Walto is in a pretty desperate search for errors on my part, whether relevant to the conversation or not.

    BTW, you may be surprised to hear that no such search need be desparate. It’s a pretty easy gig, actually.

  42. petrushka,

    I ponder my dreams pretty much every day, and I can’t recall ever thinking I’m in dream while I’m in dream.

    Then you need to try lucid dreaming. It’s really fun and interesting.

  43. petrushka: Am I conscious when I am asleep and dreaming. I certainly “think” I am.

    I’d say you are. Norman Malcolm, a Witt worshiper, once wrote a book according to which you aren’t. Don’t think he convinced more than a couple people though.

  44. keiths:
    petrushka,
    Then you need to try lucid dreaming.It’s really fun and interesting.

    There’s a few moments while waking up that I may become aware that I am both awake and dreaming. That’s the point at which I begin to analyze the dream.

    Alas, at my age, most of my morning dreams involve the urge to urinate, and the unavailability of working bathrooms.

    But some are more interesting.

    Most of my memories of dreams are visual, but i once wrote a song, including a melody. I recalled enough to write down some of it. Alas, after a few days it looked like rubbish.

  45. petrushka,

    There’s a few moments while waking up that I may become aware that I am both awake and dreaming. That’s the point at which I begin to analyze the dream.

    With practice (and the assistance of technology), you can learn to have extended lucid dreams during the middle of the night.

    Alas, at my age, most of my morning dreams involve the urge to urinate, and the unavailability of working bathrooms.

    🙁

  46. walto: Just to add why I think that. I’m guessing that Neil would not say that being taller than Jordan and shorter than Dinklage is incoherent, though it may be impossible. That is, we know what it means–in fact, that’s how we know it’s impossible.

    Exactly right. Thank you.

  47. petrushka,

    Apparently not something that philosophy wants to deal with.

    Philosophy doesn’t shy away from dreams at all.

    How do you discuss what appears to be complete conscious awareness that is divorced from perception?

    It’s not very difficult, actually. If consciousness is the result of brain states, why couldn’t those brain states occur during dreams? Why do you think they would be dependent on perception?

    From a philosopher’s perspective, how would you tell if you are in a dream?

    There are a couple of ways to interpret that question:

    1. Do human dreams have characteristics that distinguish them from normal waking consciousness?

    2. Could our normal waking consciousness itself be a dream in some higher-level reality?

    The answer to #1 is yes, and you can exploit that fact to turn regular dreams into lucid ones. The classic method is to read a snippet of text on paper, look away, and then read the text again. If the text changes, you are dreaming.

    The trick is to get yourself in the habit of performing the test while awake, so that you will also do it in your dreams.

    The answer to #2 is also yes, and that’s the point of Descartes’ evil demon, the ‘brain in a vat’ discussions, and the Matrix movies.

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