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sense that for Vladimir Russia is not here. This is the sense in which I deny
Tim s subjective facts.
6 Frank Jackson
Frank Jackson argues from physicalism to the a priori passage principle that
for each true statement concerning our world, there is a statement in physical
terms that a priori entails [it] . The validity of his argument I accept, but not
its physicalist premise, for reasons Tim Crane and I gave in Mellor and Crane
(1990) and I think Frank has not refuted. Specifically, I still think that physical-
ism faces a fatal dilemma: either all sciences (including psychology) count as
physical and it is trivially true, or it is false that, as Frank (1998: Ch. 1) puts
Real Metaphysics: replies 223
it, the kinds of properties and relations needed to account for the exemplars
of the non-sentient are enough to account for everything & contingent .
Why does Frank think they are enough? After all, his own examples, the
microphysics of water and of heat, do not account for anything sentient. Still,
they do use microscopic facts to account for macroscopic ones and, as he says
(Frank 1998: 7), the mind is a macroscopic phenomenon . That, however, is,
as he might admit, a pretty weak induction, even if his examples work; and
the fact is that they do not work. For, despite what he and many others, misled
by Kripke (1972) and Putnam (1975), have said, water is not H2O, and heat
is not molecular kinetic energy: in neither case does microphysics account in
Frank s sense for the macroscopic phenomena.
In Section 9 of my (2000b) I gave several reasons for denying that heat is
molecular kinetic energy, one of which may be summarized as follows. First,
temperatures pass my Ramsey Test for being real properties, being quanti-
fied over in many laws: the laws of thermodynamics itself, the laws linking
them to the masses, pressures and volumes of samples of given gases; to the
mean kinetic energies of gas particles; to the rates of chemical reactions; to
the frequency distributions of emitted radiation; and so on. Second, suppose
that we take the laws of thermodynamics, and those linking temperatures to
such other properties of macroscopic objects as their pressures and volumes,
to specify what Frank and others call the heat role . Then, pace Frank, this
role has at least two occupants : not only the mean kinetic energy E of gas
particles, but also the energy flux X of black-body radiation. But neither of
these can be the temperature T to which different laws of nature link them:
for, as I show in my (2000b), the way in which gas and radiation initially at
different temperatures in the same vessel must interact to reach thermal
equilibrium requires X, E and T to be distinct properties.
But what if the laws linking X, E and T are necessary, as I shall reluctantly
admit in Section 10 that they might be? Certainly, if X and T are correlated
necessarily, any energy flux X of black-body radiation will entail that its
temperature is the corresponding T. But also vice versa: the supervenience is
symmetrical, as it would be between states of mind and brain correlated by
deterministic and necessary laws. There is no sign here of the asymmetrical
supervenience that physicalism needs. And there is certainly no sign of it with
the law linking E and T, which advocates of T=E must pretend is deterministic
even though they know very well it is not. For since the real law only links any
T to a chance of the corresponding E, which, although high, is always less than
1, it will, even if it is necessary, positively prevent T supervening on E.
In short, the non-thermal kinds of properties and relations needed to
account for gas particles are not enough to account for the thermal behav-
iour of gases, which they do not even entail, never mind a priori. Similarly,
although for different reasons, with water and H2O. First, suppose we again
take the laws that link water s macroscopic properties its solvent powers,
density, freezing and boiling points, latent heats, and so on to define the
224 D. H. Mellor
water role , then to be water cannot possibly be to be H2O, since, even if we
count ice and steam as water, these allegedly identical properties have quite
different extensions. In particular, no single H2O molecule can be water, since
it instantiates hardly any of water s laws, having no solvent powers, density,
freezing or boiling points, or latent heats. Water s relation to H2O is at best
that of a heap of sand to its grains; to say therefore that it is H2O is as absurd
as saying that people are not human bodies but human cells.
Moreover, unlike a temperature, water is not for me a property at all, since
the Ramsey sentence of all laws need not quantify over it. What water names
is not a single property but a natural kind, a congeries of macroscopic proper-
ties, such as those listed above. And the microphysics of the H2O (and other)
molecules that water contains is not, as Frank supposes, enough to account
for this congeries: if only because, as we have just seen, it cannot account for
the temperature of water (nor, for example, for its pressure), on which most
of its other properties depend. But if even a mature microphysics cannot
account in Frank s sense for the most important macroscopic properties of
water, I see no reason to share his faith that the sciences of the non-sentient
will one day account in his sense for all mental phenomena. On the contrary,
to me it seems obvious that peculiarly psychological kinds of properties and
relations will always be needed to do that, just as peculiarly thermal and other
macroscopic kinds of properties are needed to account for the phenomena of
heat and of water.
7 Paul Noordhof
Epiphenomenalists owe us a theory of causation to explain why non-physical
mental entities can have causes but not effects, a debt that I agree with Paul
Noordhof they cannot discharge. All serious theories of causation link causes
to effects (or their chances) in one or both of Hume s (1748: §VII) two ways:
by counterfactuals or as instances of generalizations. And nothing about either
way stops mental entities figuring as easily in their antecedents as in their
consequents. If you would (probably) not have thought it was cold out had you
not seen the snow, why might you not have (probably) gone out had you not
thought it was cold? If everyone in brain state B (and & ) feels embarrassed,
why may not everyone who feels embarrassed (and & ) blush?
Paul discusses the stock answer to such questions, the causal closure
principle that all effects have only physical causes, and accepts my and Tim
Crane s (1990) objection that their all having physical causes does not entail
this. However, Paul thinks our argument requires non-physical causes to over-
determine their effects, and notes that an unwillingness to admit systematic
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