What is the Gap? Title 1

What is the Explanatory Gap?

David Papineau

Association for the Scientific Study of Consciousness

Berlin June 8 2009

What is the Gap? All dualists 2

The Problem is that we are All Dualists

The ‘explanatory gap’ is supposed to be some problem left after we have done the scientific work on consciousness.

I say there is no real problem here. We only think there is because we can’t stop ourselves thinking as dualists.

So the problem isn’t some business left unfinished by normal science, but simply that we aren’t scientific enough.

What is the Gap? Plan 3

The Plan1 The explanatory gap

2 The philosophical stories

3 The gap diagnosed

4 What causes intuitive dualism?(a) Ingrained culture(b) Natural-born dualism(c) The antipathetic fallacy(d) Aspirations of transparency(e) Can’t merge the files

5 Conclusions

What is the Gap? 1 Explanatory gap 4

Mind-Brain Scientific Identities

Modern materialists say that conscious states are (realized by, supervene on) brain states, just as water is H2O or heat is molecular motion.

We have an everyday kind (pain, colour vision, water, heat) and it turns out to be the same as some scientific kind (C-fibres, V-8 activity, H2O, molecular motion).

What is the Gap? 1 Explanatory gap 5

Levine’s Contrast

Joe Levine pointed out that even so the mind-brain cases strike us quite differently from the scientific ones.

Even after we are shown all the evidence, we go on asking ‘why are C-fibres felt as pains (or as anything at all)?’—but we don’t go on asking ‘why is H2O water?’

What is the Gap? 2 Philosophical stories 6

Derivations from Physics

Most philosophers think that Levine’s explanatory contrast arises because we can derive water/heat etc facts from the physical facts, in a way we can’t derive pain/seeing red etc facts.

For example, enough knowledge of atomic chemistry allows you to see that H2O must be water, but no knowledge of brain processes will allow you to see that C-fibres must feel like pain.

What is the Gap? 2 Philosophical stories 7

Contrasting Concepts

Moreover, most philosophers hold that this contrast is due to the differing ways we think about physical (water, heat) and conscious (pain, seeing red) kinds.

In the former case we pick out the kinds descriptively, as ‘the liquid which is odourless/colourless/etc . . .’, ‘the quantity that co-varies with pressure, . . .’, etc.

But in the latter case we think of the kinds more directly, in terms of what they feel like (imagine having a pain or seeing something red).

What is the Gap? 2 Philosophical stories 8

Phenomenal Concepts

Jackson and Chalmers drew our attention to this special way of thinking about conscious states (‘phenomenal concepts’) and to how they meant that no amount of physical knowledge will allow you to infer phenomenal facts so conceived from the physical facts.

What is the Gap? 2 Philosophical stories 9

Underivability and the Gap

Jackson and Chalmers tried to argue from this underivability to the falsity of materialism about conscious states.

But even philosophers who don’t think that this works as an argument against materialism still think that the underivability is the reason we have the feeling of an explanatory gap.

What is the Gap? 2 Philosophical stories 10

Underivable ≠ Unexplained

The feeling of a gap may well have something to do with phenomenal concepts, as we’ll see. But it is unlikely lack of derivability per se is the issue.

For one thing, there seem to be plenty of other cases where we can’t derive identities from the physical facts, yet don’t feel explanatorily challenged.

For example, when scientists first concluded that water = H2O, it wasn’t because they could derive odourlessness, colourlessness, etc from atomic structure—they certainly couldn’t—but simply because they knew that water and H2O were found in the same places at the same time. Yet this didn’t leave them puzzled about why water = H2O.

What is the Gap? 2 Philosophical stories 11

Nothing left Unexplained

Anyway, what exactly is supposed to be left unexplained when I believe an identity that I can’t derive from the physical facts?

‘Why a = b?’ But identities need no explanation. (Cf Mark Twain = Samuel Clemens.)

‘Why pains, say, have certain causes and effects?’ But that can be explained, given the identity.

‘Why I should believe pain is C-fibres firings?’ But that too can be explained, by reference to the correlational evidence.

What is the Gap? 3 Gap diagnosed 12

Dualist Intuitions

The reason we feel there is an explanatory gap is simply that we can’t help thinking of the mind-brain relation in dualist terms.

Even after we are shown all the evidence, and accept that mind and brain are fully correlated, we go on thinking of conscious feelings as something extra to brain processes, some further part of reality that is additional to the brain.

What is the Gap? 3 Gap diagnosed 13

Obvious Questions, Given Dualism

Insofar as we succumb to these dualist intuitions, it is of course unsurprising that we should think there remains something to be explained.

Why do certain physical processes (but presumably not others) give rise to extra feelings?

Why do they give rise to these feelings rather than others?

What is the Gap? 3 Gap diagnosed 14

Look at How we Talk

Some of you may be surprised to learn that you are closet dualists. But think of the following common phrases.

Certain brain processes 'give rise to‘, or 'generate‘, or 'yield‘, or 'cause‘, or 'are correlated with' conscious feelings.

All these phrases presuppose dualism. Fire may give rise to/generate/yield/cause/

correlate with . . . smoke. But H2O doesn't give rise to/generate/yield/cause/correlate with . . . water. It is water.

What is the Gap? 3 Gap diagnosed 15

Kripke’s Point

Philosophical zombies strike us all as intuitively possible—beings physically just like us but with no feelings.

But they shouldn’t if we were clear-headed materialists. How could there be a brain with C-fibres firing but no pain?

That would be like thinking it is possible to have Samuel Clemens without Mark Twain.

What is the Gap? 3 Gap diagnosed 16

Kripke’s Point

OK—the analogy is not perfect—in the Samuel Clemens case there is a sense he might indeed not have been Mark Twain—he mightn’t have written ‘Tom Sawyer’ etc—that is, he mightn’t have satisfied the descriptions we associate with the concept ‘Mark Twain’.

But in the mind-brain case we don’t think of pain in terms of descriptions, so we can’t be having any analogous descriptive thought when we think that C-fibre firings might not have been pains.

So the only explanation of why we think zombies are possible is that we think of the pains as distinct from the C-fibres, and therefore as possibly dissociable from them, even if perfectly correlated in the actual world.

What is the Gap? 3 Gap diagnosed 17

Good Theories and Bad Intuitions

Unlike Kripke, I don’t think this is a big problem for physicalism.

There are plenty of other cases where we find it difficult intuitively to accept what theoretically we know to be true.

(The earth moves, space is non-Euclidean, there is no moving ‘now’, the macroscopic universe splits with every quantum interaction, my status is lower than I think it is, . . .)

What is the Gap? 3 Gap diagnosed 18

Split Thinking

We simply need to recognize that our thinking is split.

At an intuitive level, we can’t help feeling that the mind is separate from the brain—and so intuitively feel an ‘explanatory gap’—why does the brain give rise to the extra feelings?

But at a theoretical level we should insist that there is just one thing there—the pains are the C-fibres firing—and so no remaining need to explain why that thing is itself.

What is the Gap? 4a Culture 19

Ingrained Culture

Why are we all in the grip of an intuition of distinctness?One possibility is that this is simply how we are brought up

to think. Our culture has long been dualist, and even after exposure to science we can’t help slipping back into the traditional dualist perspective.

Maybe. But this implies that, if our culture were to embrace mind-brain materialism, dualist intuitions will dissolve.

Some may be happy with this implication. (Stephen Yablo: ‘Am I the only one who feels the intuition of zombies to be vulnerable in this way?’)

But I suspect that there is something more structural pushing us towards dualism, something that won’t be removed just by a simple change of culture.

What is the Gap? 4b Natural dualists 20

Natural-Born Dualists

Paul Bloom thinks there is indeed a more structural reason for our persistent dualist intuitions.

We have different mental modules for thinking about intelligent agents (‘theory of mind’) and about physical objects (‘folk physics’).

Because of this, we treat items as either mental or physical but not both.

What is the Gap? 4a Natural dualists 21

Natural-Born DualistsThis offers a plausible account of why

we find it so easy to think of persons switching bodies, as in many fables and fictions.

But it doesn’t look like the whole story about mind-brain dualism.

(a) We have different modules for thinking about organisms and physical objects, yet don’t intuitively resist the idea that animal bodies are just physical.

(b) We use theory of mind to think about all intentional states, not just conscious feelings, yet don’t intuitively resist the idea that non-conscious intentional states (aims, standing beliefs) are just physical.

What is the Gap? 4c Antipathetic fallacy 22

The Antipathetic Fallacy

For many years I ascribed the intuition of dualist distinctness to what I called the ‘antipathetic fallacy’ (cf Ruskin’s ‘pathetic fallacy’).

Consider what happens when we entertain an identity like pain = C-fibres, thinking phenomenally on the l.h.s.

Since we imagine the pain on the l.h.s., but not the right, we are inclined to conclude that the r.h.s. ‘leaves out’ the pain, and only talks about its physical basis.

What is the Gap? 4c Antipathetic fallacy 23

The Antipathetic Fallacy

This is of course a fallacy—that we don’t activate the pain on the r.h.s. doesn’t mean we don’t refer to it. But it is a very seductive fallacy. (Cf McGinn: ‘How can technicolour phenomenology arise from soggy grey matter?’)

But again it doesn’t look as if this can be the whole story. Consider a claim like ‘pain = what happened in the dentist yesterday’. Even if we don’t imagine the pain on the r.h.s., we don’t here automatically feel the r.h.s. only talks about the accompaniments of pain, rather than the feeling itself (Pär Sundström).

It looks as if it is physical concepts on the r.h.s. that makes us unhappy about the identity, not just non-phenomenal concepts.

What is the Gap? 4d Aspirations transparency 24

Aspirations of Transparency

Consider this line of thought: “When we think of conscious states phenomenally, in terms

of what they are like, we are in such direct contact with them that all their essential properties should be transparent to us. But such phenomenal thinking does not reveal conscious states to be physical. So they can’t be.”

Some philosophers are prepared to defend this as a serious argument. But that’s not the issue here, so much as whether this line of thought accounts for our persistent dualist intuitions.

Maybe that is part of it. But it’s not clear that it will have much influence on people who have not reflected at length on the mind-body issue.

What is the Gap? 4e Merging files 25

Merging the Files

One popular account of what happens when we accept an identity claim a=b is that we ‘merge the files’.

Where we used to have two ‘files’ for ‘a’ and ‘b’ respectively, each containing a number of property ascriptions, we reorganise our mental architecture so as to end up with one file containing the union of these property ascriptions.

What is the Gap? 4e Merging files 26

Merging the Files

Andrew Melnyk has suggested that the source of our persistent dualist intuition is that we can’t merge files associated with (imagistic) phenomenal concepts and (symbolic) physical concepts.

A nice idea, though one that calls for further support from research on the architecture of cognition.

What is the Gap? 5 Conclusions 27

Conclusions

1 There is no reason why there should be just one cause for the persistent intuition of distinctness. Perhaps the different causes affect different people to different degrees.

2 In any case, it is clear that nearly all of us find ourselves slipping into dualist thinking when we are not vigilant.

3 The right response to the explanatory gap is not to seek out further explanations, but simply to try harder to be clear-headed materialists.