The thesis of the uniqueness of our self-consciousness

I am toying with the thesis that each person’s self-consciousness is qualitatively different. Perhaps all persons have uniquely individuating properties, something like haecceities, and for each such individuating property there is a different quale of seeing oneself as an instance of it. One might even think the quale is the unique individuating property. Or, alternately, it might be that each person’s qualia are different: my quale of red is a quale of me-seeing-red, my quale of middle-C is a quale of me-hearing-middle-C and your quale of red is a quale of you-seeing-red while your quale of middle-C is a quale of your-hearing-middle-C. There is, presumably, something that all of my qualia have in common, and all your qualia have in common, and so on.

What consequences might there be of such a view?

First, some people have the intuition that there is something mysterious about self-consciousness, something that goes significantly beyond mere consciousness (pace my thoughts here). The qualitative conscious difference thesis could be a way of capturing that mysterious extra in self-consciousness.

Second, this would be a way to support and explain intuition of the non-fungibility and irrepeatability of persons. There is something irrevocably unique about all our perceptions of the world.

Third, we might get a neat account of second-person knowledge. What happens in second-person knowledge—very mysteriously!—is that we come to see that special qualitative feature of the other, albeit in a different mode, from the outside.

Fourth, the thesis might make one even more cautious about some thorny epistemological matters. There cannot be such a thing as two people with the same qualitative evidence: each person’s evidence must be qualitatively different from that of every other person. The concept of being an epistemic peer becomes dubious: you unavoidably see the world differently from me. The application of Bayesianism to fundamental matters becomes even more fishy. Plausibly, we have essentiality of origins, so that if there is a God, you and I couldn’t have existed in a world without God. On the qualitative uniqueness thesis, this means that there are qualitative features of our mental lives that cannot be exemplified in a world without God. We can then expect that we will have some trickiness when we ask questions like: “How likely is it that the evidence I have would obtain if God didn’t exist?” Similar issues come up for fundamental laws of nature. In particular, we cannot really do Bayesian reasoning on our total evidence, and we should probably see Bayesianism as a mere toy model.

Perfect vision

One of the major themes in modern philosophy was concerns about the way that our contact with the world is mediated by our “ideas”. Thus, you are looking at a tree. But are you really seeing the tree, or are you just seeing your sense-impression, which doesn’t have much in common with the tree? Even direct realists like Reid who say you are seeing the cat still think that your conscious experience involves qualia that aren’t like a tree.

Thinking about this gives us the impression that an epistemically better way to relate to the tree would be if the tree itself took the place of our sense-impressions or qualia. Berkeley did that, but at the cost of demoting the tree to a mere figment of our perception. But if we could do that without demoting the tree, then we would be better kinds of perceivers.

However, that on some theory we would be better kinds of perceivers is not a strong reason to think that theory is true! After all, we would be better perceivers if we could see far infrared, but we can’t. It’s not my point to question the orthodoxy about our perceptions of trees.

But now think about beatitude, where the blessed see God. If seeing God is like seeing a tree in the sense that there is something like a mediating supersense-impression in us, then something desirable is lacking in the blessed. And that’s not right. Such a mediated vision of God is not as intimate as we could wish for. Would it not be so much more intimate if it were a direct vision of God in the fullest sense, where God himself takes the place of our qualia? We shouldn’t argue from “it would be better that way” to “it is that way” in our earthly lives, but in beatitude it does not seem such a terrible argument.

But where this kind of argument really comes into its own is when we think of what the epistemic life of a perfect being would be like. The above considerations suggest that when God sees the tree (and it is traditional to compare God’s knowledge of creation to vision), the vision is fully direct and intimate, and the tree itself plays the role of sense-impressions in us. We would expect a perfect being’s vision to be like that.

Now notice, however, that this is an account of God’s vision of the world on which God’s vision is partly extrinsically constituted: the tree partly constitutes God’s conscious experience of the tree. This is the extrinsic constitution model of how a simple God can know. We have thus started with us and with considerations of perfection, and have come to something like this model without any considerations of divine simplicity. Thus the model is not an ad hoc defense of divine simplicity. It is, rather, a model of the perfect way to epistemically relate to the world.

Experiencing something as happening to you

In some video games, it feels like I am doing the in-game character’s actions and in others it feels like I am playing a character that does the actions. The distinction does not map onto the distinction between first-person-view and third-person-view. In a first-person view game, even a virtual reality one (I’ve been playing Asgard Wrath 2 on my Quest 2 headset), it can still feel like a character is doing the action, even if visually I see things from the character’s point of view. On the other hand, one can have a cartoonish third-person-view game where it feels like I am doing the character’s actions—for instance, Wii Sports tennis. (And, of course, there are games which have no in-game character responsible for the actions, such as chess or various puzzle games like Vexed. But my focus is on games where there is something like an in-game character.)

For those who don’t play video games, note that one can watch a first-person-view movie like Lady in the Lake without significantly identifying with the character whose point of view is presented by the camera. And sometimes there is a similar distinction in dreams, between events happening to one and events happening to an in-dream character from whose point of view one looks at things. (And, reversely, in real life some people suffer from a depersonalization where feels like the events of life are happening to a different person.)

Is there anything philosophically interesting that we can say about the felt distinction between seeing something from someone else’s point of view—even in a highly immersive and first-person way as in virtual reality—and seeing it as happening to oneself? I am not sure. I find myself feeling like things are happening to me more in games with a significant component of physical exertion (Wii Sports tennis, VR Thrill of the Fight boxing) and where the player character doesn’t have much character to them, so it is easier to embody them, and less so in games with a significant narrative where the player character has character of their own—even when it is pretty compelling, as in Deus Ex. Maybe both the physical aspect and the character aspect are bound up in a single feature—control. In games with a significant physical component, there is more physical control. And in games where there is a well-developed player character, presumably to a large extent this is because the character’s character is the character’s own and only slightly under one’s control (e.g., maybe one can control fairly coarse-grained features, roughly corresponding to alignment in D&D).

If this is right, then a goodly chunk of the “it’s happening to me” feeling comes not from the quality of the sensory inputs—one can still have that feeling when the inputs are less realistic and lack it when they are more realistic—but from control. This is not very surprising. But if it is true, it might have some philosophical implications outside of games and fiction. It might suggest that self-consciousness is more closely tied to agency than is immediately obvious—that self-consciousness is not just a matter of a sequence of qualia. (Though, I suppose, someone could suggest that the feeling of self-conscious is just yet another quale, albeit one that typically causally depends on agency.)

Gaze dualism and omnisubjectivity

I have toyed with a pair of theories.

The first is what I call gaze-dualism. On gaze-dualism, our sensory conscious experiences are constituted by a non-physical object—the soul—“gazing” at certain brain states. When the sensory data changes—say, when a sound goes from middle A to middle C—the subjective experience changes. But this change need not involve an intrinsic change in the soul. The change in experience is grounded in a change in the gazed-at brain state, a brain state that reflects the sensory data, rather than by a change in the gazing soul. (This is perhaps very close to Aquinas’ view of sensory consciousness, except that for Aquinas the gazed-at states are states of sense organs rather than of the brain.)

The second is an application of this to God’s knowledge of contingent reality. God knows contingent reality by gazing at it the way that our soul gazes at the brain states that reflect sensory data. God does not intrinsically change when contingent reality changes—the change is all on the side of the gazed-at contingent reality.

I just realized that this story makes a bit of progress on what Linda Zagzebski calls “omnisubjectivity”—God’s knowledge of all subjective states. My experience of hearing a middle C comes from my gazing at a brain state B_C of my auditory center produced by nerve impulses caused by my tympanic membrane vibrating at 256 Hz. My gaze is limited to certain aspects of my auditory center—my gaze tracks whatever features of my auditory center are relevant to the sound, features denoted by B_C, but does not track features of my auditory center that are not relevant to the sound (e.g., the temperature of my neurons). God’s gaze is not so limited—God gazes at every aspect of my auditory center. But in doing so, he also gazes at B_C. This does not mean that God has the same experience as I do. My experience is partly constituted by my soul’s gaze at B_C. God’s experience is partly constituted by God’s gaze at B_C. Since my soul is very different from God, it is not surprising that the experiences are different. However, God has full knowledge of the constituents of my experience: myself, my gaze, and B_C, and God’s knowledge of these is basically experiential—it is constituted by God’s gazing at me, my gaze, and B_C. And God also gazes at their totality. This is, I think, all we need to be able to say that God knows my sensory consciousness states.

My non-sensory experiences may also be constituted by my soul’s gazing at a state of my brain, but they may also be constituted by the soul’s gazing at a state of the soul. And God gazes at the constituents and whole again.

Diversity of inner lives

There is a vast and rather radical diversity in the inner conscious lives of human beings. Start with the differences in dreams: some people know immediately whether they are dreaming and others do not; some are in control of their dreams and others are not; some dream in color and others do not. Now move on to the differences in thought. Some think in pictures, some in words with sounds, some in a combination of words with sounds and written words, and some without any visual or aural imagery. Some people are completely unable to imagine things in pictures, others can do so only in a shadowy and unstable way, and yet others can do so in detail. Even in the case of close friends, we often have no idea about how they differ in these respects, and to many people the diversity in inner conscious lives comes as a surprise, as they assume that almost everyone is like them.

But in their outer behavior, including linguistic behavior, people seem much more homogeneous. They say “I think that tomorrow is a good day for our bike trip” regardless of whether they thought it out in pictures, in sounds, or in some other way. They give arguments as a sequence of logically connected sentences. Their desires, while differing from person to person, are largely comprehensible and not very surprising. People are more homogeneous outside than inside.

This contrast between inner heterogeneity and outward homogeneity is something I realized yesterday while participating in a workshop on Linda Zagzebski’s manuscript on dreams. I am not quite sure what to make of this contrast philosophically, but it seems really interesting. We flatten our inner lives to present them to people in our behavior, but we also don’t feel like much is lost in this flattening. It doesn’t really matter much whether our thoughts come along with sights or sounds. It would not be surprising if there were differences in skill levels that correlated with the characteristics of inner life—it would not be surprising if people who thought more in pictures were better at low-dimensional topology—but these differences are not radical.

Many of us as children have wondered whether other people’s conscious experiences are the same as ours—does red look the same (bracketing colorblindness) and does a middle C sinewave sound the same (bracketing hearing deficiencies)? I have for a while thought it not unlikely that the answer is negative, because I am attracted to the idea that central to how things look to us are the relationships between different experiences, and different people have sets of experiences. (Compare the visual field reversal experiments, where people who wear visual field reversal glasses initially see things upside-down but then it turns right-side-up, which suggests to me that the directionality of the visual field is constituted by relationships between different experiences rather than being something intrinsic.) I think the vast diversity in conscious but non-sensory inner lives gives us some reason to think that sensory consciousness also differs quite a bit between people—and gets flattened and homogenized into words, much as thoughts are.

Trope theory and merely numerical differences in pleasures

Suppose I eat a chocolate bar and this causes me to have a trope of pleasure. Given assentiality of origins, if I had eaten a numerically different chocolate bar that caused the same pleasure, I would have had had a numerically different trope of pleasure.

Now, imagine that I eat a chocolate bar in my right hand and it causes me to have a trope of pleasure R, and immediately as I have finished eating that one chocolate bar, I switch to eating the chocolate bar in my left hand, which gives me an exactly similar trope of pleasure, L, with no temporal gap. Nonetheless, by essentiality of origins, trope L is numerically distinct from trope R.

To some (perhaps Armstrong) this will seem absurd. But I think it’s exactly right. In fact, I think it may even an argument for trope theory. For it seems pretty plausible that as I switch chocolate bars, something changes in me: I go from one pleasure to another exactly like it. But on heavy-weight Platonism, there is no change: I instantiated pleasure and now I instantiate pleasure. On non-trope nominalism, likewise there is no change. It’s trope theory that gives us the change here.

Epiphenomenalism and epistemic changes wrought by experiences

Epiphenomenalists think that there are non-physical qualia that are causally inert: all causes are physical. The main reason epiphenomenalists have for supposing the existence of non-physical qualia is Jackson’s famous black-and-white Mary thought experiment. Mary is brought up in a black-and-white room, learns all physical truths about the world, and one day is shown a red tomato. It is alleged that before she is shown the red tomato, Mary doesn’t know what it’s like to see red, but of course once she’s been shown it, she knows it, like we all do. Since she didn’t know it before and yet knew all physical truths, it follows that the the fact about what it’s like to see red goes beyond physical reality.

Now, let’s fill out the thought experiment. After she has been shown the tomato, Mary is put back in the black-and-white room, and never again has any experiences of red. It seems clear that at this point, Mary still knows what it’s like to see red, just as we know what it’s like to see red when we are not occurrently experiencing red.

So, what happened to Mary must have changed her in some way: she now knows what it’s like to see red, but didn’t know it before.

But given epiphenomenalism, this change is problematic. For it seems that it isn’t the quale of red that has changed Mary, since qualia are causally inert. It seems that Mary was changed by the physical correlate of the experience of red, rather than by the experience of red itself.

However, if this is right, then imagine Mary’s twin Martha, who has almost exactly the same things happen to her. Martha is brought up in an exactly similar black-and-white room, then shown a red tomato, and then brought back to the room. There is, however, one curious difference. During the short period of time during which Martha is presented the tomato, a supernatural being turns her into a redness-zombie, by preventing her from having any phenomenal experiences of red, without affecting any of her physical states. Since on epiphenomenalism, the experience of red is causally inert, this makes no difference to Martha’s future intrinsic states. In particular, Martha thinks she knows what it’s like to see red, just as Mary does.

But it seems that epiphenomenalist who relies on the Mary thought experiment for the existence of qualia cannot afford to say that Martha knows what it’s like to see red. For Martha is a redness-zombie in the one crucial moment of her life when there is something red for her to see. If Martha can know what it’s like to see red, so can a permanent redness-zombie. And that doesn’t seem to fit with the intuitions of those who find the Mary thought experiment compelling.

The epiphenomenalist will thus say that after the tomato incident, Mary and Martha are exactly alike physically, and both think they know what it’s like to see red, but only Mary knows. Does Martha have a true opinion, but not knowledge? That can’t be right either, since someone who has true opinion but not knowledge can gain knowledge by being told by an epistemic authority that their opinion is true, and surely mere words won’t turn Martha into a knower of what it’s like to see red. The alleged difference between Martha and Mary is very puzzling.

There is a possible story the epiphenomenalist can tell. The epiphenomenalist could say that the physical correlates of her experience of red have caused Mary to have the ability to imagine red and have visual memories of red, and this ability makes Mary into a knower of what it’s like to see red. Since Martha had the same physical correlate, she also has the same imaginative and memory abilities, and hence knows what it’s like to see red. It may initially seem threatening to the epiphenomenalist that Martha has gained the knowledge of what it’s like to see red without an experience of red, but if she has gained this by becoming able to self-induce such experiences, this is perhaps not threatening.

But this story has one serious problem: it doesn’t work if both Mary and Martha are total color aphantasiacs, unable to imagine or visually imagine colors (either at all, or other than black and white). Could the epiphenomenalist say that a color aphantasiac doesn’t know what it’s like to see red when not having an occurrent experience of red? That could be claimed, but it seems implausible. (And it goes against The Shadow’s first-person testimony that they are an aphantasiac and yet know what it’s like to see green.)

Perhaps the epiphenomenalist’s best move would be to say that no one knows what it’s like to see red when not having an occurrent experience of red. But this does not seem intuitive. Moreover, the physicalist could then respond that the epiphenomenalist is confusing knowledge with occurrent experience.

All in all, I think it’s really hard for the epiphenomenalist to explain how Mary’s knowledge changed as a result of the tomato incident.

Knowing what it's like to see green

You know what it’s like to see green. Close your eyes. Do you still know what it’s like to see green?

I think so.

Maybe you got lucky and saw some green patches while closing your eyes. But I am not assuming that happened. Even if you saw no green patches, you knew what it is like to see green.

Philosophers who are really taken with qualia sometimes say that:

1. Our knowledge of what it is like to see green could only be conferred on me by having an experience of green.

But if I have the knowledge of what it is like to see green when I am not experiencing green, then that can’t be right. For whatever state I am in when not experiencing green but knowing what it’s like to see green is a state that God could gift me with without ever giving me an experience of green. (One might worry that then it wouldn’t be knowledge, but something like true belief. But God could testify to the accuracy of my state, and that would make it knowledge.)

Perhaps, however, we can say this. When your eyes are closed and you see no green patches, you know what it’s like to see green in virtue of having the ability to visualize green, an ability that generates experiences of green. If so, we might weaken (1) to:

2. Our knowledge of what it is like to see green could only be conferred on me by having an experience of green or an ability to generate such an experience at will by visual imagination.

We still have a conceptual connection between knowledge of the qualia and experience of the qualia then.

But I think (2) is still questionable. First, it seems to equivocate on “knowledge”. Knowledge grounded in abilities seems to be knowledge-how, and that’s not what the advocates of qualia are talking about.

Second, suppose you’ve grown up never seeing green. And then God gives you an ability to generate an experience of green at will by visual imagination: if you “squint your imagination” thus-and-so, you will see a green patch. But you’ve never so squinted yet. It seems odd to say you know what it’s like to see green.

Third, our powers of visual imagination vary significantly. Surely I know what it’s like to see paradigm instances of green, say the green of a lawn in an area what water is plentiful. If I try to imagine a green patch, if I get lucky, my mind’s eye presents to me a patch of something dim, muddy and greenish, or maybe a lime green flash. I can’t imagine a paradigm instance of green. And yet surely, I know what it’s like to see paradigm instances of green. It seems implausible to think that when my eyes are closed my knowledge of what it’s like to see green (and even paradigm green) is grounded in my ability to visualize these dim non-paradigm instances.

It seems to me that what the qualia fanatic should say is that:

3. We only know what it’s like to see green when we are experiencing green.

But I think that weakens arguments from qualia against materialism because (3) is more than a little counterintuitive.

A weaker epiphenomenalism

A prominent objection to epiphenomenalist theories of qualia, on which qualia have no causal efficacy, is that then we have no way of knowing that we had a quale of red. For a redness-zombie, who has no quale of red, would have the very same “I am having a quale of red” thought as me, since my “I am having a quale of red” thought is not caused by the quale of red.

There is a slight tweak to epiphenomanalism that escapes this objection, and the tweaked theory seems worth some consideration. Instead of saying that qualia have no causal efficacy, on our weaker epiphenomenalism we say that qualia have no physical effects. We can then say that my “I am having a quale of red” thought is composed of two components: one of these components is a physical state ϕ₂ and the other is a quale q₂ constituting the subjective feeling of thinking that I am having a quale of red. After all, conscious thoughts plainly have qualia, just as perceptions do, if there are qualia at all. We can now say that the physical state ϕ₂ is caused by the physical correlate ϕ₁ of the quale of red, while the quale q₂ is wholly or partly caused by the quale q₁ of red.

As a result, my conscious thought “I am having a quale of red” would not have occurred if I lacked the quale of red. All that would have occurred would be the physical part of the conscious thought, ϕ₂, which physical part is what is responsible for further physical effects (such as my saying that I am having a quale of red).

If this is right, then the induced skepticism about qualia will be limited to skepticism with respect to unconscious thoughts about qualia. And that’s not much of a skepticism!

Knowledge of qualia

Suppose epiphenomenalism is true about qualia, so qualia are nonphysical properties that have no causal impact on anything. Let w₀ be the actual world and let w₁ be a world which is exactly like the actual world, except that (a) there are no qualia (so it’s a zombie world) and (b) instead of qualia, there are causally inefficacious nonphysical properties that have a logical structure isomorphic to the qualia of our world, and that occur in the corresponding places in the spatiotemporal and causal nexuses. Call these properties “epis”.

The following seems pretty obvious to me:

1. In w₁, nobody knows about the epis.

But the relationship of our beliefs about qualia to the qualia themselves seems to be exactly like the relationship of the denizens of w₁ to the epis. In particular, neither are any of their beliefs caused by the obtaining of epis, nor are any of our beliefs caused by the obtaining of qualia, since both are epiphenomenal. So, plausibly:

2. If in w₁, nobody knows about the epis, then in w₀, nobody knows about the qualia.

Conclusion:

3. Nobody knows about the qualia.

But of course we do! So epiphenomenalism is false.

Do you and I see colors the same way?

Suppose that Mary and Twin Mary live almost exactly duplicate lives in an almost black-and-white environment. The exception to the duplication of the lives and to the black-and-white character of the environment is that on their 18th birthday, each sees a colored square for a minute. Mary sees a green square and Twin Mary sees a blue square.

Intuitively, Mary and Twin Mary have different phenomenal experiences on their 18th birthday. But while I acknowledge that this is intuitive, I think it is also deniable. We might suppose that they simply have a “new color” experience on their 18th birthday, but it is qualitatively the same “new color” experience. Maybe what determines the qualitative character of a color experience is not the physical color that is perceived, but the relationship of this color to the whole body of our experience. Given that green and blue have the same relationship to the other (i.e., monochromatic) color experiences of Mary and Twin-Mary, it may be that they appear the same way.

If this kind of relationalism is correct, then it is very likely that when you and I look at the same blue sky, our experiences are qualitatively different. Your phenomenal experience is defined by its position in the network of your experiences and mine is defined by its position in the network of my experiences. Since these networks are different, the experiences are different. Somehow I find this idea somewhat plausible. It is even more plausible some experiences other than colors. Take tastes and smells. It’s not unlikely that fried cabbage tastes differently to me because in the network of my experiences it has connections to experiences of my grandmother’s cooking that it does not have in your network.

Such a relationalism could help explain the wide variation in sensory preferences. We normally suppose that people disagree on which tastes they like and dislike. But what if they don’t? What if instead the phenomenal tastes are different? What if banana muffins, which I dislike, taste differently to me than they do to most people, because they have a place in a different network of experiences, and if banana muffins tasted to me like they do to you, I would like them just as much?

In his original Mary thought experiment, Jackson says that monochrome Mary upon experiencing red for the first time learns what experience other people were having when they saw a red tomato. If the above hypothesis is right, she doesn’t learn that at all. Other people’s experiences of a red tomato would be very different from Mary’s, because Mary’s monochrome upbringing would place the red tomato in a very different network of experiences from that which it has in other people’s networks of experiences. (I don’t think this does much damage to the thought experiment as an argument against physicalism. Mary still seems to learn something—what it is to have an experience occupying such-and-such a spot in her network of experiences.)

More fun with monochrome Mary

Here’s a fun variant of the black-and-white Mary thought experiment. Mary has been brought up in a black-and-white environment, but knows all the microphysics of the universe from a big book. One day she sees a flash of green light. She gains the phenomenal concept α that applies to the specific look of that flash. But does Mary know what green light looks like?

You might think she knows because her microphysics book will inform her that on such-and-such a day, there was a flash of green light in her room, and so she now knows that a flash of green light has appearance α. But that is not quite right. A microphysics book will not tell Mary that there was a flash of green light in her room. It will tell her that there was a flash of green light in a room with such-and-such physical properties. Whether she can deduce from these properties and her observations that this was her room depends on what the rest of the universe is like. If the universe contains Twin Mary who lives in a room with exactly the same monochromatically observable properties as Mary’s room, but where at the analogous time there is a flash of blue light, then Mary will have no way to resolve the question of whether she is the woman in the room with the green flash or in the room with the blue flash. And so, even though Mary knows all the microphysical facts about the world, Mary doesn’t know whether it is a green flash or a blue flash that has appearance α.

This version of the Mary thought experiment seems to show that there is something very clear, specific and even verbalizable (since Mary can stipulate a term in her language to express the concept α, though if Wittgenstein is right about the private language argument, we might require a community of people living in Mary’s predicament) that can remain unknown even when one knows all the microphysical facts and has all the relevant concepts and has had the relevant experiences: Whether it is green or blue light that has appearance α?

This seems to do quite a bit of damage to physicalism, by showing that the correlation between phenomenal appearances and physical facts is a fact about the world going beyond microphysics.

But now suppose Joan lives on Earth in a universe which contains both Earth and Twin Earth. The denizens of both planets are prescientific, and at their prescientific level of observation, everything is exactly alike between Earth and Twin Earth. Finer-grained observation, however, would reveal that Earth’s predominant surface liquid is H₂O while Twin Earth’s is XYZ, but currently there is no difference. Now, Joan reads a book that tells her in full detail all the microphysical structure of the universe.

Having read the book, Joan wonders: Is water H₂O or is it XYZ? Just by reading the book, she can’t know! The reason she doesn’t know it is because her prescientific observations combined with the contents of the book are insufficient to inform her whether she lives on Earth or on Twin Earth, whether she is Joan or Twin Joan, and hence are insufficient to inform her whether the liquid she refers to as “water” is H₂O or XYZ.

But surely this shouldn’t make us abandon physicalism about water!

Now Joan and Twin Joan both have concepts that they verbalize as “water”. The difference between these concepts is entirely external to Joan and Twin Joan—the difference comes entirely from the identity of the liquid interaction with which gave rise to the respective concepts. The concepts are essentially ostensive in their differences. In other words, Joan’s ignorance of whether water is H₂O or XYZ is basically an ignorance of self-locating fact: is she in the vicinity of H₂O or in the vicinity of XYZ.

Is this true for Mary and Twin Mary? Can we say that Mary’s ignorance of whether it is a green or a blue flash that has appearance α is essentially an ignorance of self-locating facts? Can we say that the difference between Mary’s phenomenal concept formed from the green flash and Twin Mary’s phenomenal concept formed from the blue flash is an external difference?

Intuitively, the answer to both questions is negative. But the point is not all that clear to me. It could turn out that both Mary and Twin Mary have a purely comparative recognitive concept of “the same phenomenal appearance as that flash”, together with an ability to recognize that similarity, and with the two concepts being internally exactly alike. If so, then the argument is unconvincing as an argument against physicalism.

Physicalism and "pain"

Assuming physicalism, plausibly there are a number of fairly natural physical properties that occur when and only when I am having a phenomenal experience of pain, all of which stand in the same causal relations to other relevant properties of me. For instance:

1. having a brain in neural state N

2. having a human brain in neural state N

3. having a primate brain in neural state N

4. having a mammalian brain in neural state N

5. having a brain in functional state F

6. having a human brain in functional state F

7. having a primate brain in functional state F

8. having a mammalian brain in functional state F

9. having a central control system in functional state F.

Suppose that one of these is in fact identical with the phenomenal experience of pain. But which one? The question is substantive and ethically important. If, for instance, the answer is (c), then cats and computers in principle couldn’t feel pain but chimpanzees could. If the answer is (i), then cats and computers and chimpanzees could all feel pain.

It is plausible on physicalism (e.g., Loar’s version) that my concept of pain refers to a physical property by ostension—I am ostending to the state that occurs in me in all and only the cases where I am in pain, and which has the right kind of causal connection to my pain behaviors. But there are many such states, as we saw above.

We might try to break the tie by saying that by reference magnetism I am ostending to the simplest physical state that has the above role, and the simplest one is probably (i). I don’t think this is plausible. Assuming naturalism, when multiple properties of a comparable degree of naturalness play a given role, ostension via the role is likely to be ambiguous, with ambiguity needing to be broken by a speaker or community decision. At some point in the history of biology, we had to decide whether to use “fish” at a coarse-grained functional level and include dolphins and whales as fish, or at a finer-grained level and get the current biological concept. One option might be a little more natural than the other, but neither is decisively more natural (any fish concept that has a close connection to ordinary language is going to have to be paraphyletic), and so a decision was needed. And even if (i) is somewhat simpler than (a)–(h), it is not decisively more natural.

This yields an interesting variant of the knowledge argument against physicalism.

1. If “pain” refers to a physical property, it is a “merely semantic” question, one settled by linguistic decision, whether “pain” could apply to an appropriately programmed computer.

2. It is not a “merely semantic” question, one settled by languistic decision, whether “pain” could apply to an appropriately programmed computer.

3. Thus, “pain” does not refer to a physical property.

Something Mary doesn't know

Here is something our old friend Mary, raised in a black and white world, cannot know simply by knowing all of physics:

1. What are the necessary and sufficient physical conditions for two individuals to be in exactly the same phenomenal state?

Of course, her being raised in a black and white world is a red herring. I think nobody can know the answer to (2) simply by knowing all of physics.

Some remarks:

• Knowledge of the answer to (1) is clearly factual descriptive knowledge. So responses to the standard knowledge argument for dualism that distinguish kinds of knowledge have no effect here.

• The answer to (1) could presumably be formulated entirely in the language of physics.

• Question (1) has a presupposition, namely that there are necessary and sufficient physical conditions, but the physicalist can’t deny that.

• A sufficient conditions is easy given physicalism: the individuals have the exact same physical state.

• Dennettian RoboMary-style simulation does not solve the question. One might hope that if you rewrite your software, you can check if you have the same qualia before and after the rewrite. But the problem is that you can only really do exact comparisons of qualia that you see in a unified way, and there is insufficient unification of your state across the software rewrite.

The hand and the moon

Suppose Alice tells me: “My right hand is identical with the moon.”

My first reaction will be to suppose that Alice is employing some sort of metaphor, or is using language in some unusual way. But suppose that further conversation rules out any such hypotheses. Alice is not claiming some deep pantheistic connection between things in the universe, or holding that her hand accompanies her like the moon accompanies the earth, or anything like that. She is literally claiming of the object that the typical person will identify as “Alice’s hand” that it is the very same entity as the typical person will identify as “the moon”.

I think I would be a little stymied at this point. Suppose I expressed this puzzlement to Alice, and she said: “An oracle told me that over the next decade my hand will swell to enormous proportions, and will turn hard and rocky, the exact size and shape of the moon. Then aliens will amputate the hand, put it in a giant time machine, send it back 4.5 billion years, so that it will orbit the earth for billions of years. So, you see, my hand literally is the moon.”

If Alice isn’t pulling my leg, she is insane to think this. But now I can make some sense of her communication. Yes, she really is using words in the ordinary and literal sense.

Now, to some dualist philosophers the claim that a mental state of feeling sourness is an electrochemical process in the brain is about as weird as the claim that Alice’s hand is the moon. I’ve never found this “obvious difference” argument very plausible, despite being a dualist. Thinking through my Alice story makes me a little more sympathetic to the idea that there is something incredible about the mental-physical identity claim. But I think there is an obvious difference between the hand = moon and quale = brain-state claims. The hand and the moon obviously have incompatible properties: the colors are different, the shapes are different, etc. Some sort of an explanation is needed how that can happen despite identity—say, time-travel.

The analogue would be something like this: the quale doesn’t have a shape, while the brain process does. But it doesn’t seem at all clear to me that the quale positively doesn’t have a shape. It’s just that it is not the case that it positively seems to have a shape. Imagine that qualia turned out to be nonphysical but spatially extended entities spread through regions of the brain, kind of like a ghost is a nonphysical but spatially extended entity. There is nothing obvious about the falsity of this hypothesis. And on this hypothesis, qualia would have shape.

To be honest, I suspect that even if qualia don’t have a shape, God could give them the additional properties (say, the right relation to points of space) that would give them shape.

Motivating panpsychism

There is something attractive about an ontology where all the properties are powers, but it seems objectionable.

First, a power is partly defined by the properties it can produce. But if these in turn are powers, then we have a vicious regress or circularity.

At the same time, mental properties do not seem to be purely powers: they seem to have a categorical qualitative character that is not captured by the power to produce something else.

What is attractive about a pure powers ontology is the conceptual simplicity, and the fact that categorical properties seem really mysterious.

There is, however, a modification we can make to a pure powers ontology that gets us out of the problem. There are two kinds of properties: powers and qualia. The mysteriousness objection does not apply to qualia, because we experience them. On this ontology, powers bottom out in the ability to produce qualia.

For this to avoid implausible anthropocentrism, we need panpsychism—only then will there be enough qualia outside of living things for the powers of fundamental physics to bottom out in. So we have an interesting motivation for panpsychism: it yields an attractive ontology for reasons that have nothing to do with the usual concerns in the philosophy of mind.

It’s worth noting that this ontology is similar to Leibniz’s. Leibniz had two kinds of properties: appetitions and perceptions. The appetitions are (deterministic) powers. Perceptions are similar to qualia, but not quite the same, because (a) perceptions need not be conscious, and (b) perceptions are always representational. Unfortunately, the representational aspect leads to a regress or circularity problem, much as the power powers ontology did, since representationality will define a perception in terms of other appetitions and perceptions.

Forwards causal closure and dualist theories of perception

A standard dualist theory of perception goes like this:

1. You sense stuff physically, the data goes to the brain, the brain processes the data, and out of the processed data produces qualia.

There is a lot of discussion of the “causal closure” of the physical. What people generally mean by this is that the physical is causally backwards-closed: the cause of a physical thing is itself physical. This is a controversial doctrine, not least because it seems to imply that some physical things are uncaused. But what doesn’t get discussed much is a more plausible doctrine we might call the forwards causal closure of the physical: physical causes only have physical effects. Forwards causal closure of the physical is, I think, a very plausible candidate for a conceptual truth. The physical isn’t spooky—and it is spooky to have the power of producing something spooky. (One could leave this at this conceptual argument, or one could add the scholastic maxim that one cannot cause what one does not in some sense have.)

By forwards closure, on the standard dualist theory, the brain is not a physical thing. This is a problem. It is supposed to be one of the advantages of the standard dualist theory that it is compatible with property dualism on which people are physical but have non-physical properties. But if the brain is not physical, there is no hope for people to be physical! Personally, I don’t mind losing property dualism, but it sure sounds absurd to hold that the brain is not physical.

Recently, I have been thinking about a non-causal dualist theory that goes like this:

2. You sense stuff physically, the data goes to the brain, the brain processes the data, and the soul “observes” the brain’s processed data. (Or, perhaps more precisely, the person "feels" the neural data through the soul.)

To expand on this, what makes one feel pain is not the existence of a pain quale, but a sui generis “observation” relation between the soul and the brain’s processed data. This observation relation is not caused by the data, but takes place whether there is data there or not (if there isn’t, we have a perceptual blank slate). The soul is not changed intrinsically by the data: the “observation” of a particular datum—say, a datum representing a sharp pain in a toe—is an extrinsic feature of the soul. Note that unlike the standard theory, this up-front requires substance dualism of some sort, since the observing entity is not physical given the sui generis nature of the “observation” relation.

The non-causal dualist theory allows one to maintain forwards closure of the physical and the physicality of the brain. For the brain doesn’t cause a non-physical effect. The brain simply gets “observed”.

It is however possible that the soul causes an effect in the brain—for instance, the “observation” relation may trigger quantum collapse. Thus, the theory may violate backwards closure. And that’s fine by me. Backwards closure does not follow conceptually from the concept of the physical—a physical thing doesn’t become spooky for having a spooky cause.

There is a difficulty here, however. Suppose that the soul acts on the “observed” data, say by causing one to say “You stepped on my foot.” Wouldn’t we want to say that the brain data correlated with the pain caused one to say “You stepped on my foot”?

I think this temptation is resistable. Ridiculously oversimplifying, we can imagine that the soul has a conditional causal power to cause an utterance of “You stepped on my foot” under the condition of “observing” a certain kind of pain-correlated neural state. And while it is tempting to say that the satisfied conditions of a conditional causal power cause the causal power to go off, we need not say that. We can, simply, say that the causal power goes off, and the cause is not the condition, but the thing that has the causal power, in this case the soul.

On this story, if you step on my foot, you don’t cause me to say “You stepped on my foot”, though you do cause the condition of my conditional causal power to say so. We might say that in an extended sense there is a “causal explanation” of my utterance in terms of your stepping, and your stepping is “causally prior” to my utterance, even though this causal explanation is not itself an instance of causation simpliciter. If so, then all the stuff I say in my infinity book on causation should get translated into the language of causal explanation or causal priority. Or we can just say that there is a broad and a narrow sense of “cause”, and in the broad sense you cause me to speak and in the narrow you do not.

I think there is a very good theological reason to think this makes sense. For we shouldn’t say that our actions cause God to act. The idea of causing God to do anything seems directly contrary to divine transcendence. God is beyond our causal scope! Just as by forwards closure a physical thing cannot cause a spiritual effect, so too by transcendence a created thing cannot cause a divine effect. Yet, of course, our actions explain God’s actions. God answers prayers, rewards the just and punishes the unrepentant wicked. There is, thus, some sort of quasi-causal explanatory relation here that can be used just as much for non-causal dualist perception.

Fading knowledge of qualia

I am one of those people who do not have vivid memories of pains.

Suppose I stub my toe. While the toe is hurting, I know what the toe’s hurting feels like. After it stops hurting, for a while I still know what that felt like. But I know it less and less well as my memory fades, until eventually I know very little how it felt like. The whole process might take only a few minutes.

Thus, that mysterious “knowing what it’s like” involving qualia is something that comes with a parameter that varies as to how well you know it.

This should worry physicalists. Thin physicalists should worry because it doesn’t seem that the fading corresponds to any knowledge of the underlying physical reality. Thick physicalists who think that Mary just acquires a new recognitional concept when she sees red should worry, because it does not seem that there is any gradual loss of a concept. I continue to have the same “that experience” concept (the demonstrative “that” points to the same past experience, and does so in a first-personal way) and the recognitional abilities it enables (I can tell if another pain is like that one or not), even as my knowledge of what “that experience” is like fades.

It’s also not completely clear what a dualist should say about the fading of the knowledge. Normally, when knowledge fades, what happens is either that we lose details (as when I forget much of what I once learned in school about the Metis uprising), or we find the dispositional knowledge harder to make occurrent. But the fading is neither of these. Maybe what is happening is that our present knowledge becomes a less good representation of what it is the knowledge of.

Two common intuitions

Here are two very common intuitions in the philosophy of mind:

1. Our experiences of the same things are approximately qualitatively the same: your perceptual experiences of white, or squareness, or the beat of a drum are approximately like mine.

2. It is metaphysically possible to remap all of one’s qualia, so that one could have had all the color perceptions in one’s life rotated by 120 degrees, say.

I find myself somewhat sceptical of each. Moreover, each claim makes the other less likely, so the probability that both are true is less than the product of the probabilities of each.

Of the two claims, the first seems fairly plausible to me, because I am attracted to the idea that the qualitative properties of my perceptions arise from typical interconnections (including, but perhaps not limited to, inferential ones) between them, and we all have roughly the same ones. But this line of thought, while supporting (1) also supports the denial of (2).

Moreover, our use of the same word “red” for your and my experiences of red tomatoes suggests that (1) is a part of our ordinary pre-theoretic beliefs. And I am inclined to trust our ordinary pre-theoretic beliefs.

On the other hand, it could turn out that (1) is false because it could turn out that how red things look is partly a function of features of brain organization that differ from individual to individual (and in the same individual over time). If so, then we might want to disambiguate ordinary language’s “looks the same” relation to mean either having the same qualitative experience or having an experience with the same representative content, so that we could continue to say that when you and I are looking at a red tomato, it looks the same to us in the representative but not qualitative sense.

But in any case all this is deeply mysterious stuff. I am strongly inclined to the idea that we should try to figure out the best theory of mind and perception we can, and then use that to figure out if (1) and (2) are true, rather than using (1) and (2) as constraints.

Second-order perception and the knowledge argument

Here’s something odd in the knowledge argument as usually formulated. According to the knowledge argument, Mary who was raised in a black and white argument but knew all of science came to know what it is like to see red by seeing red, despite having known all the physical facts first.

But note that one cannot simply come to know what it is like to see red by seeing red. One knows what it is like to see red by having the second-order perception of oneself seeing red. When one has the first-order perception without the second-order one, one doesn’t directly know that one has the first-order perception. (One may be able to infer it, of course: Here is a tomato, my eyes are open and are pointed towards it, so I am seeing it.) Of course, typically when one has the first-order perception, one also has the second-order perception (but typically not the third-order one), but the point remains is that it is not by the first-order perception, but by the second-order one, that one learns what it is like to see red.

Presumably, any ordinary human perception can be mistaken: it can occur in the absence of its object. Thus it is possible to have the second-order perception without the first-order one. It follows that it is possible for Mary to know what it is like to see red without ever seeing red: all she needs is the second-order perception.

This does not seem to me to damage the knowledge argument as such, but merely to tweak it. For even after the above reflection, it still seems plausible that one doesn’t know what it is like to see red on the basis of physical facts, but by means of a second-order perception. Moreover, we now have an answer to the memory objection to the knowledge argument, namely that just as you and I can know what it is like to see red by having true memories of seeing red, so too someone could know what it is like to see red by having false memories of seeing red, and so actual perception of red is not needed. But this does not affect the argument once we have realized it’s about the second-order perception. For memories, true or false, of seeing red are a kind of temporally backwards second-order perception.