Philosophy 4610Philosophy 4610Philosophy of MindPhilosophy of Mind

Week 12: Week 12:

Qualia Friends and FoesQualia Friends and Foes

Qualia: The reality of a termQualia: The reality of a term Last week, we considered Nagel’s argument that it is Last week, we considered Nagel’s argument that it is

very difficult or impossible to explain conscious very difficult or impossible to explain conscious experience, or qualia, in physical terms.experience, or qualia, in physical terms.

Frank Jackson gives another argument to Frank Jackson gives another argument to demonstrate that, because of qualia, physicalism is demonstrate that, because of qualia, physicalism is probably false.probably false.

Physicalist philosophers, like Dennett, have argued Physicalist philosophers, like Dennett, have argued that pro-qualia arguments are grounded in a that pro-qualia arguments are grounded in a confusion: although there is consciousness, there is confusion: although there is consciousness, there is no such thing as qualia, and consciousness is no such thing as qualia, and consciousness is wholly explainable in physical/functional terms.wholly explainable in physical/functional terms.

Jackson and MaryJackson and Mary

To show that To show that physicalism is false, physicalism is false, Jackson considers Jackson considers the case of Mary, a the case of Mary, a gifted neuroscientist gifted neuroscientist who has spent her who has spent her whole life locked whole life locked inside a room in inside a room in which everything is which everything is colored in shades of colored in shades of black, white, or greyblack, white, or grey

““Mary is a brilliant scientist who is, for whatever Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a reason, forced to investigate the world from a black and white room via a black and white black and white room via a black and white television monitor. She specializes in the television monitor. She specializes in the neurophysiology of vision and acquires, let us neurophysiology of vision and acquires, let us suppose, all the physical information there is to suppose, all the physical information there is to obtain about what goes on when we see ripe obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like ‘red’, tomatoes, or the sky, and use terms like ‘red’, ‘blue’, and so on. She discovers, for example, ‘blue’, and so on. She discovers, for example, just which wave-length combinations from the sky just which wave-length combinations from the sky stimulate the retina, and exactly how this stimulate the retina, and exactly how this produces via the central nervous system the produces via the central nervous system the contraction of the vocal chords and expulsion of contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the air from the lungs that results in the uttering of the sentence ‘The sky is blue.’ (It can hardly be sentence ‘The sky is blue.’ (It can hardly be denied that it is in principle possible to obtain all denied that it is in principle possible to obtain all this physical information from black and white this physical information from black and white television …)” (p. 275) television …)” (p. 275)

Mary the neuroscientistMary the neuroscientist

Mary can read any fact that can be written Mary can read any fact that can be written down and can also watch demonstrations down and can also watch demonstrations on a black-and-white television.on a black-and-white television.

Over the course of years, she learns Over the course of years, she learns every physical factevery physical fact about the brain and about the brain and how it processes colorhow it processes color

Yet she has never seen anything blue. Yet she has never seen anything blue. She still does not know She still does not know what it is likewhat it is like to to see blue.see blue.

Mary and PhysicalismMary and Physicalism

After her years of research, Mary knows After her years of research, Mary knows every every physical fact physical fact about neuroanatomy, color about neuroanatomy, color processing, wavelengths, etc. (Indeed, we can processing, wavelengths, etc. (Indeed, we can assume that she knows every physical fact there assume that she knows every physical fact there is).is).

Yet she still does not know what it is like to see Yet she still does not know what it is like to see blue – she only finds this out when she exits the blue – she only finds this out when she exits the room.room.

It follows that what it is like to see blue – the It follows that what it is like to see blue – the qualequale of blueness – is not physical and cannot be of blueness – is not physical and cannot be explained in terms of physical facts. explained in terms of physical facts.

Jackson and ZombiesJackson and Zombies Another possibility that Another possibility that

Jackson suggests – Jackson suggests – what he calls the what he calls the “modal” argument – is “modal” argument – is the possibility of the possibility of “zombies” or beings “zombies” or beings without qualia.without qualia.

Zombies are physically Zombies are physically and functionally and functionally identical to us, but have identical to us, but have no conscious no conscious experience or qualia. experience or qualia.

ZombiesZombies

If Zombies are conceivable, then it is If Zombies are conceivable, then it is possible to imagine a world in which all the possible to imagine a world in which all the physical and functional facts are the same, physical and functional facts are the same, but there is no conscious experience. If but there is no conscious experience. If that is conceivable, then conscious that is conceivable, then conscious experience is experience is independent ofindependent of the physical the physical and functional facts, and cannot be and functional facts, and cannot be explained in terms of them.explained in terms of them.

Are zombies really conceivable?Are zombies really conceivable?

Dennett against qualiaDennett against qualia Dennett is a physicalist Dennett is a physicalist

who thinks there is no who thinks there is no “deep” problem with “deep” problem with explaining explaining consciousness in consciousness in physical termsphysical terms

He will argue that the He will argue that the whole concept of whole concept of “qualia” is misguided “qualia” is misguided and should be replaced and should be replaced with a description in with a description in terms of physical and terms of physical and fucntional properties.fucntional properties.

Traditional assumptions about Traditional assumptions about QualiaQualia

Qualia are traditionally taken to have Qualia are traditionally taken to have several defining properties:several defining properties: Ineffable: Can’t describe themIneffable: Can’t describe them Intrinsic: Don’t depend on any othersIntrinsic: Don’t depend on any others Private: Known only from 1Private: Known only from 1stst-person point of -person point of

viewview Immediately apprehensible: Known without Immediately apprehensible: Known without

judgment or reflectionjudgment or reflection

Dennett, however, thinks that Dennett, however, thinks that nothingnothing has has all of these properties. all of these properties.

When we see that qualia, so When we see that qualia, so characterized, don’t exist, we’ll be able to characterized, don’t exist, we’ll be able to replace the notion of qualia with replace the notion of qualia with straightforwardly physical/functional straightforwardly physical/functional notions.notions.

The Inverted SpectrumThe Inverted Spectrum The idea of the inverted The idea of the inverted

spectrum, which goes spectrum, which goes back to Locke, is the back to Locke, is the idea of a person whose idea of a person whose color-experience is color-experience is systematically inverted.systematically inverted.

The inverted spectrum is The inverted spectrum is sometimes used as an sometimes used as an argument for qualia, but argument for qualia, but Dennett will use it as an Dennett will use it as an argument against.argument against.

The Inverted SpectrumThe Inverted Spectrum

At first it seems as if the inverted spectrum case At first it seems as if the inverted spectrum case is realistic and conceivable. There could be is realistic and conceivable. There could be someone whose color-experience is directly someone whose color-experience is directly opposite to mine or yours: whenever you see opposite to mine or yours: whenever you see something red, they have a “green” quale, and something red, they have a “green” quale, and so forth.so forth.

But consider someone whose spectrum has But consider someone whose spectrum has been inverted from birth. What words will they been inverted from birth. What words will they use to describe the experiences they are use to describe the experiences they are having?having?

Even the inverted-spectrum person would Even the inverted-spectrum person would behave exactly as we do. That is, he behave exactly as we do. That is, he would call fire engines “red”, the sky would call fire engines “red”, the sky “blue”, etc.“blue”, etc.

According to Dennett, there would be no According to Dennett, there would be no functional or physical difference between functional or physical difference between us and the color-inverted person.us and the color-inverted person.

How can we even tell, then, that How can we even tell, then, that wewe are are not suffering spectrum inversion?not suffering spectrum inversion?

Chase and Sanborn, Chase and Sanborn, the coffee-tastersthe coffee-tasters

Chase and Chase and Sanborn have Sanborn have been tasting coffee been tasting coffee for many years, but for many years, but they both don’t like they both don’t like doing it anymore.doing it anymore.

Chase and SanbornChase and Sanborn

Chase thinks the taste of the coffee is Chase thinks the taste of the coffee is just the same as alwaysjust the same as always – he is getting – he is getting the same the same qualequale – but he just doesn’t enjoy – but he just doesn’t enjoy that taste, that quale, anymorethat taste, that quale, anymore..

Sanborn, by contrast, thinks the taste Sanborn, by contrast, thinks the taste (the (the qualequale) itself has changed: ) itself has changed: where he where he used to get the taste of good coffee, now used to get the taste of good coffee, now he’s getting another, different quale, one he’s getting another, different quale, one that he doesn’t enjoy as muchthat he doesn’t enjoy as much

Chase and SanbornChase and Sanborn

But can we really tell the difference But can we really tell the difference between what Chase says and what between what Chase says and what Sanborn says?Sanborn says?

If there really were qualia, then the If there really were qualia, then the difference between Chase and Sanborn difference between Chase and Sanborn would make sense. But Dennett argues would make sense. But Dennett argues that it does not: there is actually no that it does not: there is actually no meaningful difference between what meaningful difference between what Chase says and what Sanborn says.Chase says and what Sanborn says.

Quining Qualia: ConclusionsQuining Qualia: Conclusions If Dennett is right and it is impossible to tell the If Dennett is right and it is impossible to tell the

difference between Chase and Sanborn, then there difference between Chase and Sanborn, then there is no need to postulate “qulia” to explain the taste-is no need to postulate “qulia” to explain the taste-judgments we make.judgments we make.

There are just these judgments themselves, but we There are just these judgments themselves, but we can explain these fully in terms of physical and can explain these fully in terms of physical and functional facts that are perfectly accessible from a functional facts that are perfectly accessible from a third-person, objective point of view. third-person, objective point of view.

Thus there is no special “hard” problem of Thus there is no special “hard” problem of explaining consciousness. It’s just a matter of time explaining consciousness. It’s just a matter of time until we have a good physicalist explanation of how until we have a good physicalist explanation of how consciousness works. consciousness works.