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									      What is the Explanatory

                   David Papineau

       Association for the Scientific Study of
                Berlin June 8 2009
What is the Gap?         Title                   1
       The Problem is that we are All
The „explanatory gap‟ is
   supposed to be some
   problem left after we have
   done the scientific work on
I say there is no real problem
   here. We only think there is
   because we can‟t stop
   ourselves thinking as
So the problem isn‟t some
   business left unfinished by
   normal science, but simply
   that we aren‟t scientific
What is the Gap?             All dualists   2
                            The Plan
            1 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?                    Plan       3
   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         4
                   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?        1 Explanatory gap   5
           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           6
               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            7
             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   8
        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           9
       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 =
What is the Gap?       2 Philosophical stories            10
           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
„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?            2 Philosophical stories   11
                   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
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   12
 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
Why do they give rise to these feelings
  rather than others?
What is the Gap?    3 Gap diagnosed               13
                   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            14
                   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
What is the Gap?       3 Gap diagnosed          15
                   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                   16
  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
(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   17
                      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
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?               3 Gap diagnosed   18
                   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?          4a Culture                      19
               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?        4b Natural dualists   20
               Natural-Born Dualists
This 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

What is the Gap?                   4a Natural dualists   21
            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

What is the Gap?              4c Antipathetic fallacy   22
            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
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

What is the Gap?         4c Antipathetic fallacy               23
      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
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?      4d Aspirations transparency           24
                   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

What is the Gap?             4e Merging files   25
                   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

What is the Gap?              4e Merging files   26
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.

What is the Gap?      5 Conclusions                 27

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