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.

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.

A weird escape from the Knowledge Argument?

Take Jackson’s story about Mary who grows up in a black-and-white room, but learns all the science there is, including the physics and neuroscience of color perception. One day she sees a red tomato. The point of the story is that in seeing the red tomato, she has learned something, even though she already knew all the science, so the science is not all the truth there is, and hence physicalism is false.

This story is generally told in the context of the philosophy of mind, and the conclusion drawn is that physicalism about the mind is false. But that does not actually follow without further assumptions. As far as the argument goes, perhaps Mary didn’t learn anything about herself that she didn’t already know, but has learned something about tomatoes, and so we should conclude that physicalism about tomatoes is false.

Let’s explore that possibility and see if this hole in the argument can be filled. I will assume (though I am suspicious of it) that indeed the kind of knowledge gap that Jackson identifies would imply an ontological gap. Thus, I will accept that Mary has learned what it is like to see the red of a tomato, and that the knowledge of what it is like to see the red of a tomato is not a knowledge of physical fact.

Can one say this and yet accept physicalism about the mind? The one story I can think of that would allow that is a version of Dretske’s qualia externalism: just as most of us think that the content of our thoughts is partly constituted by external facts, so too the qualitative character of our perceptions is partly constituted by external facts. But in fact for the story to work as a way of blocking the inference to non-physicalism about the mind, the qualia (understood as that in the experience that cannot be known by Mary by mere book-learning) would need to be entirely constituted by extra-mental facts.

I think this kind of qualia externalism is not all that crazy. Divine simplicity requires that all of God’s knowledge of contingent fact be partly constituted by states of affairs outside God. But it is plausible that God has something like contingent qualia: that were God to contemplate a world with unicorns, it would “look” different to God than our world. On divine simplicity, we would need to have externalism about these qualia.

That said, the above affords no escape from literal anti-physicalism about the mind. If physicalism about the mind is true, then minds are brains. But if we accept that colored things have a nonphysical component that partly constitutes the perceiver’s qualia, then brains have a nonphysical component, since brains are colored things, namely pinkish (here is a description of their color in vivo, though I cannot vouch for its accuracy).

Maybe, though, this misses the point in the debate. The typical dualist thinks that there is something different about minds and other physical things. If it turns out that minds are just brains, but that they are not physical simply because their pinkness is not entirely a physical property, that’s really not what the dualist was after. The dualist’s intuition is that there is something radically different in the human brain, something not found in a pink sunset cloud (unless it turns out that panpsychism is true!).

Maybe this works to save a more robust dualist conclusion: Plausibly, one doesn’t need a tomato to make Mary have a red sensation. All one needs is to do is to induce in her brain’s visual centers the same electrical activity as normally would result from her seeing a red tomato. And the equipment inducing that electrical activity need not be red at all.

Color-remapping

I’ve often wondered what would happen if one wore color-remapping glasses. Would the brain adapt, and everything would soon start looking normal, much as it does when you wear vision-inverting prisms. Well, it turns out that there is an interesting two-subject (the investigators) study using LCD glasses linked to a camera and did a color-space rotation. They found interesting results, but found that over six days there was no adaptation: stop signs still looked blue, the sky still looked green, and broccoli was red. This is not conclusive, since six days might just not be long enough. I would love to see the results of a longer study.

The philosophical relevance, of course, is to inverted-spectrum thought experiments.

Colors and transsubstantiation

This is going to be very speculative, and I doubt it yields an orthodox account of transsubstantiation, but since there is some chance that it does yield such an account (and if it doesn't, we might get a deeper picture of transsubstantiation by thinking about why it fails), it's worth thinking about.

Let's say, as a first approximation, that an object is white at a spacetime region U provided that the object has a direct causal power of reflecting light incident on U diffusely and approximately uniformly across the visible spectrum. Observe that in this definition nothing was said about U being a region that is occupied by the object. It is logically possible for an object to have a causal power of action at a spatial and/or temporal distance, thereby diffusely and approximately uniformly reflecting light incident on a region unoccupied by the object. Now suppose that a white piece of bread is going to be destroyed, but just before it is destroyed the causal power of whiteness that it has is enhanced to work at a temporal distance, thereby diffusely and approximately uniformly reflecting light incident on a spatial region shaped like a piece of bread in the future after the destruction of the piece of bread. Then there is a sense in which the whiteness of the piece of bread persists after the destruction of the piece of bread.

It seems there are two senses in which we can say that the whiteness of an ordinary object is at a location V. One sense is that the relevant causal power is located at V and the other sense is that the object is directly causing light to be reflected whitely at V. The location of the accident of whiteness can be identified either with the location of the causal ground of the reflection or with the location of the immediate effect of that causal ground (the second matches how Aquinas understands the locations of angels: they are deemed present where they act). Normally, the two locations coincide or are very close together. So there is a a sense in which, in the scenario where the bread has the power of causing white reflections after its destruction, the accident of whiteness exists at the location where the reflection occurs, and hence continues to exist after the destruction of the bread.

Colors and time

I am inclined to think we are four-dimensional (or, more precisely, (n+1)-dimensional, where n is whatever number of dimensions space turns out to have) beings, but that we do not have temporal parts. So what do I say about apparently monadic properties that one can change in respect of, like being red? My preference is to say that these properties are, in fact, non-monadic. For instance, "I am beige" (or whatever color term correctly indicates the current typical shade of my skin) expresses the fact that I beigely occupy the present, where the present is a spacelike hypersurface.

Presentists can say, more simply, that "I am beige" expresses my being beige simpliciter. So it seems that on theoretical simplicity grounds, presentists win out. But I think this is mistaken. For whereas presentists need to posit two properties—a monadic being beige and a binary beigely occupying—eternalists of my sort need only posit a single binary property of beigely occupying. (Of course, the presentist could analyze her being beige in terms of beigely occupying the present, but then the presentist loses the advantages of the theory.)

Here is a reason why the presentist needs a binary beigely occupying. I am beige on my left half. (I am also beige on my right half, but nevermind that.) Given a relational beigely occupying, I can let L be the region of spacetime occupied by my present left half, and analyze "I am beige on my left half" as "I beigely occupy L." But this uses the relation of beige occupation.

I do not think this can be done with mere monadic beigeness. The best way I know of rendering "I am beige on my left half" in terms of monadic beigeness is something like "My left half is beige." But there is no such object as my left half. Cutting me in half is not cutting nature at its seams, and if there are such things as parts at all, they are obtained by cutting nature at its seams. But it's worse than that. Suppose there were such an object as my left half. It wouldn't be beige! For one of that object's surfaces—the one where the object meets my right half—would be mainly bloody red.

One might try to talk of the left half of my surface being beige. But a surface has two sides, which can have different colors, and so we would still need a non-monadic property: being beige on the outside/inside. Or at least a pair of monadic properties. But not just the plain monadic being white. Besides, I don't think we have surfaces. Those would be weird things in the case of beings whose material components are made up of particles or that have blurred wavefunctions.

So, the presentist also needs beige occupation in addition to beigeness. But isn't it simpler to just analyze the latter in terms of the former?

Color perception

Here's another data point towards a theory of perception. My son, 4, is colorblind (or color perception deficient or whatever the right term these days is). He was looking at the dark red flowers on his mom's blouse, and said they were black. He was told they were red, and he accepted that—he is very accepting of the fact that colors aren't what they seem to him as. I then asked him if they looked red to him after he was told they were red. He was very definite about an affirmative answer to this question.