In his book Physicalism, or Something Near Enough, Jaegwon Kim puts forward the
following characterization of the materialist supervenience thesis:
I take
supervenience as an ontological thesis involving the idea of
dependence – a sense of dependence that justifies saying that a mental property
is instantiated in a given organism at a time because, or in virtue of the
fact that, one of its physical “base” properties is instantiated by the
organism at that time. Supervenience, therefore, is not a mere claim of
covariation between mental and physical properties; it includes a claim of
existential dependence of the mental on the physical. (p. 34)
Kim goes on to deploy this thesis as a component of his influential “causal exclusion argument,” which is directed against non-reductive physicalists who accept supervenience but deny that the mental can be identified with the physical, and who also reject the epiphenomenalist claim that the mental has no causal efficacy. In Kim’s view these theses cannot all be held together. The basic idea is that if (a) every mental event supervenes on a physical event, (b) every physical event has a physical cause sufficient to produce it (the “closure” thesis), and (c) no event has more than one sufficient cause (the “exclusion” thesis), then it seems that there is nothing for the distinctively mental attributes of any event to do. Hence the physicalist either has to embrace epiphenomenalism or, to save the causal efficacy of the mental, accept the reductionist thesis that mental properties are not merely supervenient upon, but identical to, physical properties. (Kim spells out the argument more carefully and at greater length both in the book and in other writings.)
What
concerns me in this post, however, is not the mind-body problem but rather an
interesting and perhaps unexpected parallel Kim draws with some views on the
nature of divine causation put forward by theologian Jonathan Edwards (of
“Sinners in the hands of an angry God” fame).
Edwards took the occasionalist position that God is the only true
efficient cause of everything that occurs, so that the apparent causal efficacy
of everyday objects is illusory. In a
passage quoted by Kim in Physicalism,
Edwards compares this purported illusion with the illusion that mirror images
have causal efficacy:
The images of things in a glass, as we keep our eye upon them, seem to remain precisely the same, with a continuing, perfect identity. But it is known to be otherwise. Philosophers well know that these images are constantly renewed, by the impression and reflection of new rays of light; so that the image impressed by the former rays is constantly vanishing, and a new image impressed by new rays every moment, both on the glass and on the eye… And the new images being put on immediately or instantly do not make them the same, any more than if it were done with the intermission of an hour or a day. The image that exists at this moment is not at all derived from the image which existed at the last preceding moment. As may be seen, because if the succession of new rays be intercepted, by something interposed between the object and the glass, the image immediately ceases; the past existence of the image has no influence to uphold it, so much as for a moment. (Doctrine of Original Sin Defended, Part IV, Chapter II)
The images of things in a glass, as we keep our eye upon them, seem to remain precisely the same, with a continuing, perfect identity. But it is known to be otherwise. Philosophers well know that these images are constantly renewed, by the impression and reflection of new rays of light; so that the image impressed by the former rays is constantly vanishing, and a new image impressed by new rays every moment, both on the glass and on the eye… And the new images being put on immediately or instantly do not make them the same, any more than if it were done with the intermission of an hour or a day. The image that exists at this moment is not at all derived from the image which existed at the last preceding moment. As may be seen, because if the succession of new rays be intercepted, by something interposed between the object and the glass, the image immediately ceases; the past existence of the image has no influence to uphold it, so much as for a moment. (Doctrine of Original Sin Defended, Part IV, Chapter II)
The idea
here is this. It might seem like the
mirror image of an object at time t1 is what causes the subsequent
mirror image of the same object at time t2. But that is not the case, and in fact the
image at t1 does not cause anything.
Rather, it is the object itself which causes both the image at t1
and the image at t2. Now, in
a similar way, it seems that (say) the movement of one billiard ball on a pool
table causes the movement of a second billiard ball a moment later. But that (claim occasionalists like Edwards)
is also an illusion. It is rather God
who causes both the movement of the first ball and the movement of the second,
and the first billiard ball has no more efficacy than the mirror image. There are also no persisting objects
(including the billiard balls) but rather a succession of fleeting objects
created successively by God, which only appear
to constitute persisting things in the way that the image in the mirror
falsely appears to be one thing persisting over time.
There is, as
Kim indicates, an interesting implicit parallel here to Kim’s causal exclusion
argument (though Kim himself doesn’t explicitly draw out all of these
parallels). You could read Edwards as
presenting a challenge to his fellow theists that is analogous to Kim’s
challenge to his fellow physicalists. Just
as Kim begins with the fact that both he and other physicalists accept the
supervenience of the mental on the physical, Edwards begins with the fact that
theists affirm the supervenience of all things on God – that is to say, they
affirm the doctrine of divine conservation, according to which the world could
not persist in being even for an instant unless God were continually causing it
to exist.
And just as
Kim’s argument could be deployed as a defense of epiphenomenalism – the thesis
that mental attributes don’t really have any causal efficacy, but only falsely
appear to – so too Edwards’ argument is a defense of occasionalism – the thesis
that ordinary objects don’t really have any causal efficacy, but only falsely
appear to. An epiphenomenalist inspired
by Kim would say: “If the mental supervenes on the physical, then (given
certain further premises) the physical does everything and there’s really
nothing for the mental to do.” And
Edwards is basically saying: “If ordinary objects supervene on God, then (given
certain further premises) God does everything and there’s really nothing for
ordinary objects to do.”
Now, there
is the difference that Kim’s position is actually framed as a dilemma, whereas
Edwards’ is not. Kim is saying that the
physicalist either has to opt for
epiphenomenalism or opt for a
reductionist identification of the mental with the physical. A strictly parallel Edwardsian argument would
pose a dilemma according to which the theist either has to opt for occasionalism or opt for a reductionist identification of ordinary objects with
God. The latter option would really
amount to a kind of pantheism on which ordinary objects just are God perceived
under different aspects. To perceive one
billiard ball hitting another is really just to perceive God acting under one
aspect, to perceive the sun melting an ice cube is really just to perceive God
acting under another aspect, and so on.
Then again,
it is not clear in either case that the horns of the dilemma are really all
that different. Start with the mental-physical
case. Even on the reductionist horn of
Kim’s dilemma, the mental arguably has no more efficacy than it does on the
epiphenomenalist horn. For example, even
if the reductionist physicalist identifies the belief that it is raining with a certain brain process, it is very
hard for the physicalist to avoid the conclusion that it is still the
neurophysiological properties of that brain process, and not its intentional
content, that end up doing all the causal work.
The distinctively mental attributes of a mental state are either made
epiphenomenal after all or implicitly eliminated.
From a
Thomistic point of view, this is exactly what we should expect given the
Scholastic metaphysical principle agere
sequitur esse or “action follows being” – the thesis that the way a thing acts reflects the manner in which it exists.
If a thing does not really do
anything at all, then neither can it truly be said to be real.
It is for
this reason that some Thomists argue that occasionalism collapses into
pantheism, so that the occasionalist and pantheist horns of the dilemma that
Edwards’ position might seem to generate also end up not being very
different. Hence, just as Kim’s position
arguably leads to the implicit elimination of the mental, Edwards’ position arguably
leads (whatever his intentions) to the elimination of everyday objects and the
conclusion that God alone is real.
Be that as
it may, does Edwards really show that divine conservation entails occasionalism
(whether or not it also entails pantheism)?
No. Note that Kim’s dilemma
follows not from supervenience by itself, but only from supervenience together with his additional assumptions
about causation (the closure and exclusion theses). Similarly, Edwards’ conclusion would follow from
divine conservation only if we were
to accept certain explicit or implicit further assumptions that he is making
about causation. And Thomists would not
accept those assumptions.
This turns
out to be example #1,234 of how the acceptance or rejection of the
Aristotelian-Thomistic (A-T) analysis of causation has a ripple effect across
the philosophical and theological landscape.
Edwards thinks that the relation of an object at t1 and the
same object at t2 is like the relationship between the mirror image
at t1 and the mirror image at t2, and that what is in
question in each case is whether the first bears a relationship of efficient causality to the second. Just as the mirror image at t1 is
not the efficient cause of the mirror image at t2, so too the object
at t1 is not (so the argument seems to go) the efficient cause of
the object at t2. (Here, by
the way, I am interpreting Edwards’ position the way Kim does, or at least the
way Kim’s use of him suggests. I am not
doing Edwards exegesis, and I don’t think Kim is claiming to do so either, but
merely examining a view that one could
derive from his text.)
But this is
at best a highly misleading way of characterizing the situation. It is true that there can be no question of
efficient causation between two objects here, but that is the case not because of
some parallel with the mirror example, but rather for the simple reason that
there aren’t two objects in the first
place, but only one object, albeit one that exists at both times. Perhaps Edwards is thinking (as many contemporary
philosophers would) in terms of a causal relationship between distinct events at t1 and at t2,
or between distinct temporal parts at
those two times. But we A-T philosophers
would say that there are no such things as temporal parts, and that it is things rather than events that are in
the strict sense efficient causes.
So, even if
we allow that the mirror images at t1 and t2 are distinct
things of which we may ask whether or not they are related by efficient causation,
it is just a muddle to think that a physical
object at t1 and t2
amounts to distinct things of which we may ask the same question. The analogy between mirror images and physical
objects is simply not a good one, so that it isn’t clear why we should take it
to support an occasionalist conclusion.
To be sure,
there is a sense in which it might be
said that there is a kind of causal relation between an object at t1
and the same object at t2.
But it has to do, not with efficient causation, but rather with formal and material causation. The
objects at t1 and t2 are the same object, not because something
at t1 serves as an efficient cause of something at t2,
but rather because it is the same composite of prime matter and substantial
form at both times. It is only if we try
to reduce all causation to the efficient kind that it will seem that we need to
understand an object’s persistence over time in terms of efficient causation,
and then conjure something like events or temporal parts to serve as the
purported relata. And it is only once we
have done that that we will be led to make the further mistake of thinking that
there is some interesting analogy here with the mirror images, so that we start
pondering (as the occasionalist does) whether to keep the purported relata
while dropping the efficient-causal relation between them.
Another
problem is that the Kim-style argument for occasionalism that Kim seems to be
attributing to Edwards seems to presuppose that when we speak of divine
causation and of efficient causation between physical objects, we are speaking
univocally. And for the Thomist that is
simply not the case. For one thing,
where divine conservation and concurrence are concerned, God’s causality is of
a primary or underived kind, whereas the causality of physical things is of a secondary or derivative kind. For another
thing, we are in all cases applying the concept of efficient causation to God
in an analogical way, since the sort
of causal circumstances that apply to physical objects (spatial contiguity,
transfer of energy, etc.) cannot intelligibly apply to that which is
immaterial, atemporal, absolutely simple, etc.
The upshot
is that divine causation and the causation that physical objects exhibit are
simply not in competition with one another, the way that an occasionalist application
of the exclusion principle requires that they be. To suppose they are in competition is like
supposing that I cannot see the geometry
book in front of me and at the same time see that the Pythagorean theorem is true, on the grounds that the
Pythagorean theorem is not located where the book is and thus is not in my line
of sight. The fallacy here is that the word
“see” is not being used in the same, univocal sense in both claims, but rather in
analogical senses. I don’t see the
theorem in the same sense in which I see the book, even though I really do see
both.
It is similarly
fallacious to suppose that if God is the ultimate cause on which the activity
of billiard balls, the sun, etc. supervenes, then there is nothing left for
them to do. For physical objects do not
cause things in the same, univocal sense in which God does, but rather in an
analogical sense. It is true both that God causes the second billiard
ball to move and that the first billiard
ball causes it to move, without any competition, redundancy, or overdetermination,
because they are “causing” it in different senses. (For the same reason, it is no less
fallacious to suppose that if the physical objects have real causal efficacy,
then there is nothing left for God to
do – an atheist rather than occasionalist error. But that is another issue.)
Related
posts:
0 Comments