Thursday, July 15, 2021

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.


Mark Cuthbertson said...

Suppose one doesn't need external electrical equipment at all to induce the appearance of the color green. Can't I imagine the appearance of green? Sure, I could imagine the appearance of a unicorn, yet that wouldn't constitute an actual unicorn. But the appearance of green IS green.

Alexander R Pruss said...

The appearance of green is not green (as far as we know), just as the appearance of squareness is not square (there are no squares in your mind).

Mark Cuthbertson said...

Well, in the last experiment, the sensation in question (for which, I think, the external electrical equipment isn't required...and like the external equipment, the brain itself isn't red or green) is to Mary certainly colored red. And potentially it's colored red in a way that would be indistinguishable to her from a sensation caused by light waves of a certain red-inducing length. What is red/green if not that appearance? You hadn't seemed to require it have a physical component, unless I misunderstood.

Unknown said...

I feel like even if we grant qualia externalism, this doesn't get to the heart of the hard problem of consciousness, which is the existence of, and irreducibility of, a "first person" subjective experience, which is a power or reality that cannot be sufficiently described by appeal to any third person properties. Maybe external qualia could help the physicalist when it comes to the knowledge argument, but not with the zombie argument, for example.

Unknown said...

Also, the point of the knowledge argument is to show how there is no logical supervenience between qualia and physical properties. Whether or not qualia are external, just knowing all the physical, quantitative, scientific facts etc., Mary won't know what red is like if she can't actually *experience* red. There'd also be no reason for why an apple would be qualia-red rather than some other qualia-color. It would be an utterly contingent relation.

Alexander R Pruss said...


The experience presents something _as red_. That doesn't mean that there is anything colored red there, just as a book can present a building as enormous, without there being anything enormous there.


I don't find the zombie argument very persuasive. I think zombies are possible, but my main reason for thinking this is that I already accept dualism. :-)

I don't see why there couldn't be a law of nature that says that things that reflect light of certain wavelengths are qualia-red.