“Epiphenomenal Qualia”

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Frank Jackson

• Australian philosopher.• Distinguished Professor

at the ANU.• Awarded the Order of

Australia.• Delivered the 1995 John

Locke Lectures.

THE KNOWLEDGE ARGUMENT FOR QUALIA

Trichromatic Vision

Normal human retinas contain three types of light-sensitive cone cells (they also contain light-sensitive rods that are not part of color vision).

The brain uses the stimulation of these cells to discriminate visual stimuli by color.

Trichromatic Vision

Trichromatic Vision

Most mammals have only 2 types of cone cells, but primates like monkeys, apes and humans have 3.

One evolutionary suggestion is that 3 types of cells helps for finding ripe fruit.

Trichromatic Vision

Most mammals have only 2 types of cone cells, but primates like monkeys, apes and humans have 3.

One evolutionary suggestion is that 3 types of cells helps for finding ripe fruit.

Tetrachromatic Vision

The ancestors of mammals, and the cousins of mammals (like birds) have 4 types of cones.

Tetrachromatic Vision

Scientists think that some human women also have 4 cones and thus see about 100 times more colors than normal people.This is because women can carry two different versions of one cone on their two X chromasomes.

Fred

Jackson asks us to imagine a person named Fred who has the following ability. He can sort any pile of red things (like tomatoes) that all look the same to us into two piles.

If you mix the piles up again, Fred can sort them back into the exact same two piles.

Fred

Fred claims that the things in the two piles appear to be two different colors (to him). He calls them both “red” because that’s what other people do, but he says that look to him as different as yellow and blue.

Fred

Supporting Fred’s claim is the fact that he has 4 cones in his retinas, not just 3 like normal humans. Scientists discover that the light-sensitivity of his additional cone matches the wavelengths of light reflected by some red things.

The Knowledge Argument

• We know all the science behind Fred’s brain states, how he has different cones, how they’re sensitive to different wavelengths, etc.

• We know the functional roles of the brain states: how those states work to discriminate between wavelengths that we can’t discriminate between.

• We know everything that physicalist theories of mental states appeal to.

The Knowledge Argument

• We do not know what the color Fred sees is like.

• We do not know what Fred’s color experience is like.

• Therefore, since we know all the (relevant) physical facts, these other facts we do not know must be non-physical facts.

Mary

“The same point can be made with normal people and familiar colors.”

Mary

• Brilliant scientist.• Locked in a room with

nothing red-colored since birth.

• Has never seen her own blood or anything else that’s red.

• Knows everything about color science and brain science.

Mary

1. Mary knows all the physical facts (about others).

2. There is something that Mary does not know: what seeing red is like (for others).

3. Therefore the fact that seeing red is like this is not a physical fact.

Clarification #1

It’s doubtful that not having seen red makes it impossible for you to imagine what red is like.

Jackson is not saying this. He is saying that one person, Mary, cannot imagine what seeing red is like.

Clarification #2

We saw before that arguments like this are bad:

Lois Lane believes that Superman can fly.Lois Land does not believe that Clark Kent can fly.__________________________________Therefore, Superman ≠ Clark Kent.

Clarification #2

Isn’t Jackson just saying:

Mary knows that George’s L-cones are active.Mary doesn’t know that George is experiencing red.________________________________Therefore, George’s L-cones being active ≠ George experiencing red.

Clarification #2

No. Jackson is arguing that

L-cones fire when one experiences red

cannot be a physical fact. If it’s a physical fact then since Mary knows all the physical facts, she knows that

L-cones fire when one experiences red.

Clarification #2

Then we can argue:

Mary knows that George’s L-cones are firing.Mary knows that L-cones fire when one experiences red.______________________Therefore, Mary knows that George is experiencing red.

Recap

1. Mary knows all the physical facts (about others).

2. There is something that Mary does not know: what seeing red is like (for others).

3. Therefore the fact that seeing red is like this is not a physical fact.

THE MODAL ARGUMENT

The Modal Argument

1. It is possible for there to be someone exactly like me in all physical properties who has no conscious mental states (a “zombie”).

2. Therefore mental states can’t be the same as physical properties. (Because having the same physical properties does not necessitate having the same mental states.)

3. Therefore, there are non-physical properties.

Problems

• Some philosophers don’t think that claim #1 is true.

• They argue, for example, that just because we can imagine people so-described doesn’t mean that they are actually possible.

• Even some philosophers*** who are non-physicalists disagree with #1. They say that consciousness is closely linked with physical states, even though not identical to them.

The Knowledge Argument

Jackson claims that the knowledge argument is not the modal argument.• Nowhere does Jackson assume that

philosophical zombies are possible.• He does not claim that Mary is physically the

same as someone who does know what red is like.

• He uses “normal people and familiar colors.”

NAGEL’S ARGUMENT

Jackson’s Misrepresentation

Jackson interprets Nagel as arguing that we can’t imagine what it’s like to experience bat-experience tokens. Nagel was clear that he meant types.

Jackson’s Misinterpretation

“No amount of knowledge about Fred, be it physical or not, amounts to knowledge ‘from the inside’ concerning Fred. We are not Fred. There is thus a whole set of items of knowledge expressed by forms of words like ‘that it is I myself who is…’ which Fred has and we simply cannot have because we are not him.” p. 276

The Ability Objection

Next, Jackson takes the “ability” line on Nagel

“It is hard to see an objection to Physicalism here. Physicalism makes no special claims about the imaginative or extrapolative powers of human beings, and it is hard to see why it need do so.” p. 276

The Upshot

• Jackson’s argument is not Nagel’s argument.• Jackson does not appeal to the fact that Mary

can’t imagine what it’s like for me to see red. He doesn’t need to assume that she can imagine anything at all.

• Jackson’s argument rests on the claim that there is a fact that Mary does not know, even though she knows all the physical facts.

THE BOGEY OF EPIPHENOMENALISM

Epiphenomenalism

Epiphenomenalism (as Jackson wants to defend it): some properties of mental states are perhaps causally efficacious. BUT, the property of being conscious, or having a certain qualitative feel never causes anything.

Objection #1

The conscious feel of my pain is what causes me to say “ouch!” or “it hurts!” The conscious experience of red causes me to think there’s something it’s like for me to see red.Mary’s experience of red on leaving the room causes her to believe that she lacked knowledge of other people’s mental lives.Etc.

Jackson Responds

Correlation does not imply causation.

Saying “it hurts” usually comes after/ during feeling pain. But that doesn’t mean that it causes the pain.

Example

When we watch a movie, it seems like the image of someone pulling a gun trigger causes the image of a bullet firing. But the images on the film have no causal relation to one another.

Objection #2

According to the theory of evolution by natural selection, complex functions evolve only when they confer a reproductive advantage. Conscious mental states seem to have evolved, they fulfill a complex function, and yet according to epiphenomenalism they cannot covey any advantage at all (they are causally inefficacious).

Jackson Responds

Traits can be evolutionarily selected for either because they convey an advantage or because they are necessary consequences of something that conveys an advantage.

Example: Spandrels

Why do spandrels exist? It seems like on many old buildings they served an artistic purpose. But that’s not why they’re there. They have to be there to hold the building up.

Evolutionary “Spandrels”

A polar bear has a heavy coat. Why? Doesn’t this make the bear slower and require that it spend more energy to move? The explanation is that the coat isn’t there because it’s heavy, it’s there because it’s warm. Warmth requires heaviness.

Jackson’s Idea

Conscious mental states aren’t around because they are conscious. They are around for other purposes they serve (functional role, for example). However, there is a close connection between having a certain functional role and being conscious.

Objection #3

Obviously, how things behave is evidence for what conscious mental states they are in. Rocks don’t howl or squeal when you kick them, and that’s a good reason to think they are not conscious. Dogs do howl and squeal when you kick them, and that’s a good reason to think that they are conscious.

Causes

Causes

Is Evidence For

Causes

Causes

Is Evidence For

Occam’s Razor

“We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. Therefore, to the same natural effects we must, so far as possible, assign the same causes.” – Isaac Newton

Objection #4

We shouldn’t believe in things that don’t cause anything that we can observe, and don’t explain anything we can observe. According to the epiphenomenalist, qualia are such things. So we shouldn’t believe in them.

Jackson’s Slugists

Jackson wants us to imagine intelligent slugs who live at the bottom of the sea. They have an advanced science that explains everything they’ve observed. But there’s so much more to the world than that!

Jackson’s Slugists

The idea is that we are the slug philosophers (slugists). There’s more than what our science has or can discover.We shouldn’t assume that because qualia don’t fit into our scientific explanatory scheme that therefore they don’t exist.