Symbols
N
= a particular neural state
P
= a particular pain
W
= a particular wince
Causal
Overdetermination?
Jaegwon
Kim says that it's a particular neural state (N)
which is the “supervenience base” of my toothache.
Thus
what if I winced (W) from my pain (P)? What would have
caused that wince? Surely it must have been the pain that caused me to
wince. Kim, on the other hand, believes that it's a particular neural
state that caused me to wince. Or, as Kim himself puts it, N
is “causally sufficient for wincing”.
Is
there a difference between N and the mental experience of the
pain? If N and P are two different things, then both N
and P might have caused me to wince. However, according to Kim,
this would be a case of something being “causally overdetermined”.
Why
does it automatically follow that if two things cause a third thing
that this third thing is causally overdetermined? It may take two
or more things to cause a third thing. Actually, there can be many causal
conditions which are required to bring about a particular effect.
Of
course overdetermination has been widely discussed in philosophy.
(E.g., in the ontology of objects and in the philosophy of
science.) However, Kim doesn't got into detail in the papers I've
consulted. The following is probably the reason why.
If
P and N are one and the same thing, then to say that
both P and N (as separate phenomena) cause W is
a case of overdetermination because they're the same thing. Though
that's not really causal overdetermination: it's thinking that one
thing is two things. Thus, in actual fact, there's no genuine
overdetermination.
In
any case, there's an alternative to this possible overdetermination
which involves a three-way journey from N to the wincing.
We
can have a chain from N to P to W. Yet Kim says that N
and P are perfectly simultaneous. There's no causal journey
from N to P because they occur at one and the same
time....Do they? It's indeed the case that human cognition can't register the time-lapse
between N and P; though that doesn't mean that there is no time-lapse. The interval might have been milliseconds. And even
if only a millisecond, that would still have constituted a temporal and "causal gap"
between N and P.
Kim completely rejects this causal gap. Indeed he doesn't even
discuss the possibility that it may exist. Instead he says that P
“supervenes on” (or is “realised by”) N: it's
“not caused by it”.
Thus
supervenience isn't a relation of causation. When we say that P
supervenes on N, that doesn't mean that N causes P.
It means that P simply supervenes on N... Though what
exactly does that mean?
Can
such supervenience occur without causation? If it does, then how and why
is that the case? And if this applies to the relation between N
and P, does it also apply to all mental states and
their supervenience-bases?
For
example, say I form a mental image of David Cameron. That means that
I can't say that neural or brain state N causes my mental
image of Cameron. All I can say is that the mental image supervenes
on a particular neural/brain state. Though, again, what exactly does
that mean?
What
is the Causal Role of Pain?
So
what had the main “causal role” in my wincing? Was it N or
P?
If
N doesn't cause P (i.e., P supervenes on N),
then perhaps that question doesn't make sense. Perhaps both N
and P caused W. Though Kim has just said that this is a
case of overdetermination. If that's the case, then wouldn't that mean,
surely, that Kim wants to get rid of either N or P?
Kim
can't get rid of N because there'd be no pain without a
neural state. So can he get rid of the pain itself? Surely not. Would
I have winced without a (mental) pain? Of course not... surely.
Kim,
at a prima facie level, does seem to want to get rid of P.
Or at least he writes that “if we trace the causal chain backward
from the wincing, we are likely to reach N first, not the
pain”. Indeed he continues by saying that it's
“incoherent
to think that the pain somehow directly, without an intervening chain
of physiological processes, acted on certain muscles, causing them to
contract; that would be telekinesis, a strange form of action at a
distance!”.
This
seems to be a denial that the purely mental can act on the physical.
Or, at the least, that the mental can only act on the physical if the
mental itself is physical. (Or if it, in this case, supervenes on the
physical.) That would be the Cartesian or dualist position which Kim
rejects. Indeed something purely mental acting on the physical (in
this case, on muscles) would be like “telekinesis” or “action
at a distance”. I suppose this is a reference to a presupposed
(metaphorical?) distance between the pain (qua purely mental) and the
physical. The only way out of that would be to see the mental and
physical as one – otherwise we would have telekinesis or action at
a distance.
Kim,
of course, doesn't reject either pain or the mental generally.
Instead he says that “if the pain is to have a causal role, it must
somehow ride piggyback on the causal chain from N to the
wincing”. (We'll need to discover what exactly “pain riding
piggyback on N” actually means.)
As
stated, Kim firmly rejects what he called the overdetermination that
is “two independent causal paths”. That would be one from N
to the wincing and the other from the pain to the wincing”. The
simple way out is to see N and P as one. Though how can
a neural state and pain be as one? That was the question that was
asked by old-style identity
theorists as well as by dualists. The only difference here, it
seems, is the introduction of the notion of supervenience.
Though is that notion satisfactory and/or acceptable?
Is
Pain Epiphenomenal?
The obvious conclusion to all this is to say that P
is epiphenomenal. And that's what Kim does seem to say.
So
is there a difference between the following? -
P
supervenes on N.
P
is epiphenomenal.
In
other words, if P is truly epiphenomenal, then it “is wrong
to think of pain as a causal effect of N”. In the end, then,
a question has to be asked: What purpose does P serve?
In
fact earlier in the paper Kim himself cites an analogical case. In
this example he refers to the shadows of a moving car. He writes:
“The
shadows are caused by the moving car but have no effect on the car's
motion. Nor are the shadows at different instants causally
connected...”
And
then Kim compares the car's shadows with someone's toothache. He
writes:
“Similarly,
you may think that the pain in your tooth has caused your desire to
take aspirin, but that, according to epiphenomenalism, would be a
mistake: Your toothache and your desire for aspirin are both caused
by brain events, which themselves may be causally connected, but the
two mental events are not related as cause to effect any more than
two successive car shadows.”
Again
we can ask: If all that's the case, then what purpose does the
pain serve? After all, according to Kim, it's
“[b]eing
real and having causal powers go hand in hand; to deprive the mental
of causal potency is in effect to deprive it of its reality”.
(The problems with that view is that it would also make numbers, past events, propositions, etc. unreal.)
Indeed
without the pain working as a genuine cause, aren't we talking here
about a simple mechanical cause and effect without the interaction of
any kind of mentality? If the toothache, in this instance, has no
causal role, then what role does it have?
Reductionism
or Eliminativism?
Kim's
solution to all this seems to be old-style reductionism. Or at least
he puts the reductionist position when he says that the “reductionist
identifies pain with neural state N”.
Indeed
in another paper Kim does argue that pain as a "scientific kind... must
go” and that elimination or reduction is the answer. That's
primarily because - in Kim's case at least - of the problems
associated with the multiple realisability of mental kinds in
many and various physical substrates.
Although
I won't go into detail on this, this is what Kim himself writes on
this subject:
“....
the frank acknowledgement that MR [multiple realisability] leads to
the conclusion that pain as a property or kind must go. Local
reduction after all is reduction, and to be reduced is to be
eliminated as an independent
entity.”
As
I said, it's clear that Kim accepts that pain and mental
states/qualities exist: it's just that they aren't deemed to be
scientific kinds or properties.
However,
when putting the case for supervenience, Kim also identified P
with N with the addition of supervenience. Unless,
of course, such a reduction can exist side-by-side with supervenience.
In
any case, Kim happily finishes off by saying that
“reductionism
has been rejected by the majority of philosophers of mind for what
they take to be compelling reasons”.
References
Kim,
Jaegwon, 'Multiple
realization and the metaphysics of reduction' (1992)
-
'Mental Causation' (chapter 6) in his Philosophy
of Mind (1996)
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