Philosophy E156: Philosophy of Mind

Fall 2013Week 14:

Dennett on Qualia: Part Two

Mental Objects and Mental Properties

• Suppose, then, that we give up thinking that there exist “mental objects.”

• Still, we might ask, are there any reasons left to embrace the existence of mental properties?

• Previously we had an argument for the existence of mental properties – that they were the properties of purely mental objects, the sense data.

• But without the mental objects, we no longer have that reason to accept their existence.

Qualia• A subcategory of mental properties are what we call “qualia.”• Obviously, if we are talking about the mental properties of

sense data, we are talking about “qualia.”• It’s useful to recall Frank Jackson’s examples of qualia at the

beginning of “Epiphenomenal Qualia”:– “the hurtfulness of pains”– “the itchiness of itches”– “pangs of jealousy”– “the characteristic experience of tasting a lemon, smelling a rose,

hearing a loud noise or seeing a sky”• All these are unproblematic except “pangs of jealousy.”

Two Uses of the Term “Qualia”• Sometimes instead of “qualia” we use the terms “qualitative

properties” or “properties with qualitative character” or “phenomenal properties”

• Some philosophers use the term “qualia” to mean purely mental properties – for them, it is part of the meaning of the term that qualia are purely mental and thus nonphysical.

• Other philosophers, like me, use the term only to mean “properties with qualitative character” or “phenomenal properties” – the properties of experiences by virtue of which there is something it is like to have them.

• In that case, it is conceivable qualia might be physical.

Three Positions on Qualia• We will use the term “qualia” in my way, although it

is important always to be clear about which way the term is being used.

• That then leaves open three possible positions about qualia (the position names are mine):– Qualia Reductionism: Qualia exist and are physical

properties.– Qualia Dualism: Qualia exist and are nonphysical

properties. This is a form of property dualism.– Qualia Fictionalism: Qualia are fictions and thus do not

exist. This is a form of eliminativism.• The position that qualia exist is Qualia Realism.

Why the Distinction Between the Two Uses of “Qualia” Aren’t Made

• There is a set of arguments against physicalism based on the sensory properties of experiences, on what it is like to have the experiences.

• These arguments, if sound, would prove that – (1) qualia exist,

but also that – (2) qualia are nonphysical properties.

• It is because these arguments do both (1) and (2) that “qualia” are seen as inherently nonphysical.

Arguments for Qualia Dualism (Property Dualism)

• I will now review a set of arguments that are supposed to establish the falsity of physicalism and the truth of property dualism.

• They would also establish the truth of qualia realism and of qualia dualism.

• Most have appeared since 1970, but they owe an inspiration to Descartes.

Kripke’s Argument in Naming and Necessity

• In 1970, Saul Kripke gave lectures at Princeton that later appeared under the title Naming and Necessity.

• Kripke takes the conceivability that one thing is distinct from something else to mean that it is really possible, so long as it is impossible to explain away – to explain away, in Kripke’s words, as an “illusion of contingency.”

Kripke’s “Heat and Molecular Motion” Example

• For example, consider heat and molecular motion. • It may seem that we can conceive that heat isn’t molecular

motion. But on Kripke’s account, this is an illusion. • What we are thinking when we seem to be able to imagine

that, Kripke argues, is not that we might have molecular motion without heat. Rather, it is that we might have molecular motion without the sensation of heat – that is, without feeling hot.

• We confuse heat – which is what makes us feel hot – and the sensation of heat – feeling hot itself. Thus, the conception that purports to distinguish heat and molecular motion is an illusion (not “clear and distinct”) – an “illusion of contingency,” as Kripke calls it.

Why There Is No Such Illusion for Kripke in the Pain Case

• Kripke’s point is that when we turn to pain and its physical counterpart – call it for the sake of argument “C-fiber stimulation” – we cannot identify any “illusions of contingency.”

• It may seem that we can conceive that heat isn’t molecular motion. On Kripke’s account, this is an illusion, the result of failing to distinguish heat from the sensation of heat.

• Likewise, it may seem that we can conceive that pain isn’t C-fiber stimulation. But in the case of pain, we cannot identify an illusion, since pain just is the same as the sensation of pain.

• Thus, there is no parallel confusion to be identified with regard to pain.

• Thus, what seems possible when we imagine pain without any physical counterpart really is possible – or at least seems so.

Kripke’s Creation Metaphor and Chalmers’ Zombie Metaphor

• Kripke puts his case this way: When God created the world, he says, he had to do more than just create the physical aspects of the world. There was more to do. He still had to create consciousness – what it is like to experience the world.

• In The Conscious Mind, David Chalmers puts the point this way: that there is a world physically identical to our world yet lacking consciousness – a world of what he calls “philosophical zombies” – and therefore that the facts of consciousness are “further facts about our world, over and above the physical facts.”

• It may seem that these notions are too bizarre to be taken seriously, but both Kripke and Chalmers are aware of how wild these ideas are – on their view (and I think they are right about this) their arguments depend only what is logically possible, not what is actually the case.

Dualism as an Explanation• It is easy with all the oddities of these arguments to lose sight of what

dualism is for. Dualism, whether it is token dualism or property dualism, is offered as an explanation of something. It is offered as an explanation of consciousness.

• Ordinarily, an explanation should tell us how something originates or what it consists of. We have neither sort of explanation for consciousness.

• One thing that makes this odd is that consciousness is all-pervasive. It is not something arcane, unfamiliar, encountered only in exotic experiments in a laboratory. Consciousness, in a very real sense, is us.

• Another thing that makes this odd is that not only do we not have an explanation -- we don’t even have a candidate for an explanation of its origin or its constitution.

• Even if it were a correct explanation, it would not be a very satisfactory one, because it tells us nothing about the origin or the constitution of consciousness

We Are Only Driven to Dualism by Logic

• If it isn’t satisfactory as explanation, why dualism, then?• Dualism is offered as an explanation not because it does what

we want an explanation to do but because it seems to be the outcome of a logical argument. – The Cartesian argues that we can conceive of existing

without a body -- or, alternatively, can conceive of a world physically identical to this one existing without consciousness.

– So it is supposed to follow on the basis of logic alone that dualism is true -- it is conceivable, thus possible, and thus, by certain metaphysical principles governing things and properties, actual.

• The non-Cartesian arguments like Kripke’s and the other I will now examine are of a different form, but much the same thing can be said of their uneasy connection to explanation.

Nagel’s Bat Argument• In his well-known essay “What Is It Like to Be a Bat?”, Thomas

Nagel reminds us that bats seem to have a very different form of experience than we human beings do, something we find ourselves unable to fully imagine.

• This is because they get around by echolocation.• Nagel takes this to be a sensory modality we do not have. • Thus, Nagel says that we do not know what it is like to

echolocate. We might be able to imagine some parts of what it is like (e.g., hanging upside down), but there are gaps. Only the bat knows fully.

• Only from the bat’s point of view could one know fully.

A Formal Argument

• Based on these facts, Nagel appears to give the following argument:

• Physical properties are knowable from any point of view.• What it’s like to echolocate is knowable only from the• bat’s point of view .

• ∴ What it’s like to echolocate is not a physical property.

A Problem with Nagel’s Argument

• Nagel himself seems to have recognized a difficulty with this argument, which I will illustrate by the property of blushing.

• You cannot understand that someone is blushing unless you have the human concept of blushing, and you probably cannot have that concept unless you have undergone blushing.

• If that’s right, then that someone is blushing is knowable only from the blusher’s point of view. But surely it is false that blushing is not a physical property. The form of argument is thus fallacious.

• The problem is with the first premise. Here is a physical property that cannot be attributed from every point of view.

A Revision of the Bat Argument• But while this first argument goes wrong, another argument

based on the facts from Nagel’s article fares better. • Bat scientists are known as chiropterists. • Imagine for the sake of argument a superchiropterist. This

person, let us suppose, is not only the world’s authority on bats but knows everything a chiropterist could ever possibly hope to know about bats.

• Yet since our superchiropterist is human, there will still be limitations. Since our superchiropterist could not know fully what it was like to be a bat, there would be gaps in even this person’s knowledge.

A Modified Version of the Argument

• Thus, consider the following revision of the initial argument:

• The superchiropterist knows everything physical there is to know about bats.

• The superchiropterist does not know everything about• bats. . • ∴ There are truths that escape the physicalist’s story.

Jackson’s Mary Argument• Revised argument makes it look like Jackson’s Mary

argument.• The revised Nagel argument, Jackson’s Fred argument and his

Mary argument are all known as “knowledge arguments.”• Jackson’s Mary argument probably the most discussed

argument for property dualism – one of the most discussed arguments in philosophy, generally – of the last 30 years.

• Tells us to consider experiences of superneuroscientist Mary. • Through her neurological research, Mary is as knowledgeable

about as much of the physical world as you like – – on one version, about the entire human visual system, – on another, about every physical aspect of human beings, – on another, about the entire physical world.

• She has expertise that I will call complete. • Confined throughout her life to a b&w room & with access to

the outside world only through b&w TV, Mary has never experienced anything red. On her release, she finally does.

How Jackson Formalizes His Argument

• Jackson presents his argument for property dualism this way:

– Mary (before release) knows everything physical and functional there is to know about other people.

– Mary (before release) does not know everything there is to know about other people (learning something about them on release).

– ∴ There are truths about other people (and herself) which escape the physicalist story of the world.

What a Knowledge Argument Says

• According to a Knowledge Argument, there are certain things which you can know everything physical about but not know everything about and which, because of that, make physicalism (or materialism) false.

• A Knowledge Argument says that your having this extra knowledge – the knowledge about these things which you could have over and above your knowledge of everything physical about them -- depends on the existence of special properties, what I have been calling qualia.

• A Knowledge Argument purports to show qualia exist. • Moreover, it purports to show that qualia are nonphysical and

that, because of this, physicalism is false. • Once again, the positions which it purports to establish I am

calling property dualism, qualia realism and qualia dualism.

A Comparison Between Jackson’s Argument and Kripke’s

• Let me point out a comparison to Kripke’s argument. • Where Kripke says that its possible (for God) to

create everything physical about the world without creating everything, Jackson says that it is possible (for Mary) to know everything physical about the world without knowing everything.

• On both stories, this is supposed to mean that there are “further facts” to the world beyond all the physical facts – eerie, nonphysical facts of consciousness – nonphysical qualia.

A Cartesian-Like Knowledge Argument

• There is a Cartesian-like knowledge argument:I can doubt everything physical about myself.I cannot doubt everything about myself. .

∴ There is something missing from the physicalist story about me.• The first premise seems validated by Descartes’s thought

experiment. Descartes seems able to place into doubt everything physical about the external world.

• The second premise is supported by Descartes’s reasoning that, despite these doubts about the physical world, he exists and is a thinking thing.

• If Jackson’s conclusion holds, this one, which is derived by the same form of reasoning, does as well.

Two Materialist Stategies Against Jackson’s Knowledge Argument

– Mary (before release) knows everything physical and functional there is to know about other people.

– Mary (before release) does not know everything there is to know about other people (learning something about them on release).

– ∴ There are truths about other people (and herself) which escape the physicalist story of the world.

• The first, associated with Dan Dennett and Paul Churchland (and represented by the writings on the course website), is to claim that the two premises are inconsistent: that holding onto the first means giving up the second.

• The second strategy, associated with David Lewis and a number of other writers, is to claim that the argument stands in need of a third premise but that none is available.

The Dennett-Churchland strategy • Dennett-Churchland strategy doesn’t fare well if examined closely.• The general strategy is to argue that Jackson’s premises are

inconsistent, or at least that Jackson has not shown them not to be:– (1) Mary (before release) knows everything physical and

functional there is to know about other people. – (2) Mary (before release) does not know everything there is to

know about other people (learning something about them on release).

• Actually, Dennett makes three sorts of counterarguments:• First Argument: We don’t know what it would mean for (1) to be true.• Second Argument: We have no reason to think Mary would be

surprised by color on release, and thus no reason to think she learns.• Third Argument: We have reason to think Mary could “figure out”

what color is like before release, and thus reason to think she does not learn.

Dennett’s 1st Argument: We don’t know what it would mean for (1) to be true

• From pp. 399-400 of Consciousness Explained: – “The crucial premise [in Jackson’s argument] is that ‘She knows

all the physical information.’ That is not readily imaginable, so no one bothers. They just imagine that she knows lots and lots.... It is of course true that in any realistic, readily imaginable version of the story, Mary would come to learn something, but in any realist-ic, readily imaginable version she might know a lot, but she would not know everything physical. Simply imagining that Mary knows a lot, and leaving it at that, is not a good way to figure out the implications of her having ‘all the physical information’--any more than imagining she is filthy rich would be a good way to figure out the implications of the hypothesis that she owned everything.”

My reply to the 1st Argument: That we don’t know what it would mean for (1) to be true• My reply to the Dennett’s First Argument –

that we don’t know what it would mean for (1) to be true – is, roughly speaking, – “Yes and no.”

• Yes, I can grant much of what Dennett says• But no, Dennett misinterprets Jackson and as

a result he mislocates the burden of proof that Jackson has

What I can grant in Dennett’s First Argument

• I can grant this much: yes, we are in no position to spell out all the implications of somebody’s knowing everything – Just as we are probably also in no position to spell out all

the implications of somebody’s owning everything • And he is obviously correct that just knowing the implications

of somebody’s knowing “lots and lots” would not be enough– No more than knowing the implications of somebody’s

owning “lots and lots” would be enough to spell out all the implications of somebody’s owning everything

• In both cases, many implications could only be known empiri-cally -- by carrying out experiments and studies, perhaps only on one who knew everything or one who owned everything

• Perhaps there are implications that could not be known at all

Is Mary Omniscient?

• Still, it is not obvious that Jackson’s specific conclusions about Mary’s knowing everything are among the implications that could only be known empirically or not at all

• Nor is it made more obvious by what Dennett writes• Part of the attraction of Dennett’s objection is the idea, unstated but I

believe lurking in the background, that what Jackson is asking us to imagine is that Mary is omniscient

• What would it be for somebody literally to know everything physical?• Here’s a physical thing: that the patches on this screen constituting

the words in this sentence appear at the particular place they appear• Is that one of the physical things Mary knows? • If she knows literally everything physical, then that would have to be

one of the things that she knows.

Knowledge of “Other People”

• Recall that Jackson’s premise (1) is about Mary’s knowledge of “other people”• (1) Mary (before release) knows everything physical and

functional there is to know about other people.

• As I have spelled out this fact about the light on the screen, it is not a fact about other people

• But if I now add that it is positioned a certain distance away from you – roughly between 10 feet and 25 feet, depending on where you sit – now we have a fact about “other people”

How Much Knowledge Does the Knowledge Argument Require?

• So is it that Jackson is asking us to imagine that Mary is omniscient in that way, knowing all the facts of that sort?

• Well, remember what Jackson says that it is in virtue of that Jackson’s first premise is true.

• It is not supposed to be true in virtue of the fact that Mary catalogues random trivial facts.

• Rather, it’s that she knows the truths of completed sciences -- completed physics, completed chemistry, completed neurophysiology, and so forth.

Just Enough for There to Be “Completed Science”

• So even though Jackson writes the first premise in the way he does, we’re not supposed to take it to mean that Mary knows literally every physical fact in the way that God would but rather only that she knows every principle of the relevant completed sciences

• That’s still a lot to know, but it doesn’t require that Mary be omniscient

• She just knows all that somebody who does her kind of science knows once that kind of science is completed

Dennett’s Confusion

• So I think that there’s something a bit confused about this initial objection from Dennett, that we cannot imagine what it would be like for someone to know all that Mary knows.

• Surely that is true, if we are supposed to imagine that she is omniscient.

• But it’s less convincing as the scope of Mary’s knowledge decreases.

• Jackson’s argument does not require – nor does it presuppose – genuine omniscience.