This old entry, which had been languishing in the old Powerblogs archive, still strikes me as making some important and plausible points. Here it is again, spruced up and supplemented.
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There are philosophers who seem to think that doctrines held by great philosophers and outstanding contemporaries don't need to be studied and refuted but can be shamed or ridiculed or caricatured out of existence. Daniet Dennett is an example:
Dualism (the view that minds are composed of some nonphysical and
utterly mysterious stuff) . . . [has]been relegated to the trash
heap of history, along with alchemy and astrology. Unless you are
also prepared to declare that the world is flat and the sun is a
fiery chariot pulled by winged horses unless, in other words,
your defiance of modern science is quite complete you won't find
any place to stand and fight for these obsolete ideas. (Kinds of
Mind, Basic Books, 1996, p. 24)
This is an amazing passage in that it compares the views of distinguished dualist philosophers such as Richard Swinburne to the views of astrologers, alchemists, and flat-earthers. It would be very interesting to hear precisely how the views of Swinburne et al. are in "defiance of modern science" — assuming one doesn't confuse science with scientism. But let's look at what Dennett has to say in his more substantial (511 page!) Consciousness Explained (1991).
Dennett there (mis)characterizes dualism as the doctrine that minds are "composed not of ordinary matter but of some other, special kind of stuff. . . ," and materialism as the view that "there is only one sort of stuff, namely matter — the physical stuff of physics, chemistry, and physiology — and the mind is some nothing but a physical phenomenon." (33) "In short, the mind is the brain." (33)
Plausibly and charitably read, however, a substance dualist such as Descartes does not hold that minds are composed of some extraordinarily thin intangible stuff. The dualism is not a dualism of stuff-kinds, real stuff and spook stuff. 'Substance' in 'substance dualism' does not refer to a special sort of ethereal stuff but to substances in the sense of individuals capable of independent existence whose whole essence consists in acts of thought, perception, imagination, feeling, and the like.
Dennett, who often comes across as a sophist, is exploiting the equivocity of 'substance' as between stuff and entity metaphysically capable of independent existence. For example, when we speak of Socrates as a substance, we are not referring to his proximate or ultimate matter, but to his capacity for existence on his own, in contrast to his pallor which, as an accident of Socrates as substance, cannot exist on its own but only in a substance, and indeed only in the very substance of which it is the accident, namely, Socrates.
The main point is made very well by the prominent idealist, T. L. S. Sprigge:
It is often difficult to get people to realize that the
non-physical mind of which Cartesians speak is not, as some have
thought it, 'a ghost in the machine' of the human body, since
ghosts and 'spirits' such as might appear in a seance are, in
contrast to it, as physical, if made of a finer stuff, as our
ordinary bodies. When we speak of the mental we do so mostly or
entirely in metaphors (more or less sleeping) of a physical kind:
we grasp ideas and have thoughts in our minds. Whatever the real
source of this materialism which is endemic to most of our
thinking, it is not surprising that there should be a theory of
existence which follows its leadings. As thinkers we are subjects,
but the natural object of thought is objects and it is only with
effort that the subject turns its thoughts upon its own
un-object-like nature. (Theories of Existence, pp. 46-47, bolding
added.)
Dennett Plays the Interaction Card (Canard?)
Now Dennett trots out the "standard objection to dualism" which to Dennett is decisive. Ignoring non-interactionist types of substance dualism, Dennett tells us that mind and body, if distinct things or substances, must nonetheless interact. But how could the mind act upon the brain? How could a mental state make a difference to a brain state if mental states lack physical properties?
A fundamental principle of physics is that any change in the
trajectory of any physical entity is an acceleration requiring the
expenditure of energy, and where is this energy to come from? It is
this principle of the conservation of energy that accounts for the
physical impossibility of "perpetual motion machines," and the same
principle is apparently violated by dualism. This confrontation
between quite standard physics and dualism . . . is widely regarded
as the inescapable and fatal flaw of dualism. (35)
Now any unprejudiced person should be able to see that this "fatal objection" is inconclusive. Notice first of all that Dennett is
presupposing that mental-physical causation must involve transfer of energy. For Dennett's objection is essentially this:
a. Energy must be transferred to a physical entity to cause a change
in it.
b. No energy can be transferred from an immaterial to a material
entity.
Therefore
c. No immaterial entity such as a mind can cause a change in a
material entity such as a brain/body.
But why should we accept the first premise? Why should we endorse a transfer theory of causation? Note that to assume a transfer theory of causation is to beg the question against the dualist: it is to assume that the mind must be material. For only a material thing can be a term in an energy transfer. Dennett thinks that dualism must collide with standard physics because he foists upon the dualist a conception of causation that the dualist will surely reject, a conception of causation that implies that there cannot be any nonphysical causes.
The materialist says: mind and body cannot interact because interaction requires transfer of energy, and only bodies can be the
transferers and transferees of energy.
The interactionist dualist says: Since mind and body do interact, interaction does not require transfer of energy.
Let M be a type of mental event and B a type of brain event, and let m and b be tokens of these types. Perhaps there is nothing more to causation than this: m causes b =df (i) b follows m in time; (ii) Whenever an M even
t occurs, a B event occurs. On this regularity approach to causation, Dennett's objection dissolves.
Indeed, on any theory of causation in which causation does not consist in a transfer of a physical magnitude from cause to effect, Dennett's objection dissolves. Therefore, the objection can be made to stick only it is assumed that the transfer theory of causation is true of all types of causation. But then the question has been begged against dualist interaction.
There are two key points here that need to be developed in subsequent posts. One is that the nature of causation is not a physics problem. The natural scientist can tell us what causes what, but is singularly ill-equipped to tell us what causation is. The second point is that it is not at all clear that causation, even in the physical world, is a physical process. It is not all clear, in other words, that the causal structure of the physical world is itself something physical.
Dennett thinks that the incoherence of dualism is so obvious that it doesn't require "the citation of presumed laws of physics." (35). Casper the Friendly Ghost is all the help one needs. He can pass through a wall, yet grab a falling towel. But that's incoherent, since something that eludes physical measurement cannot have physical effects. The mind, as 'ghost in the machine,' is no better off. Only physical things can move physical things. But the mind of the substance dualist is not a physical thing, ergo, the mind cannot act upon the body.
But again, Dennett is just begging the question against the dualist as I have already explained.