Atheism and Theism JJ Haldane - Common Sense Atheism

154 J.J.C. Smart
a definite way. We can explain the behaviour of the receiver by physics
together with a wiring diagram. Thus in the sense in which we might think
of electronics (or part of it) as physics plus wiring diagrams, so the biochemical
core of biology can be thought of as physics and chemistry plus natural
history. 6 Of course the natural history needn’t be about tigers or gum trees:
investigating the small structures seen by means of electron microscopes counts
for me as natural history. In natural history we have mere generalizations, to
which exceptions are the norm, hardly requiring explanation, and relating
to things on planet earth, and so cosmically parochial. Thus consider a
biochemical investigation of the functioning of a liver. ‘Liver’ is understood
partly ostensively and partly in terms of what it usually does, what it has been
selected for. 7
One can therefore be an ontological physicalist without believing in emergence
in any stronger sense than the weak sense that I have just elucidated. 8
Nor need we be able to make detailed predictions from one level to the next
to have good scientific and philosophical reasons to see the higher level as not
only ontologically a matter of the lower level but as plausibly explained by it.
Steven Weinberg puts the matter very persuasively in his Dreams of a Final
Theory. 9 He argues as follows. The quantum theory of the chemical bond can
be used in cases of simple atoms and molecules to explain the properties of
the chemical bond, and even if this cannot be done in the case of very
complicated molecules, this failure can be put down simply to the mathematical
intractability of the problem. Because the nature of the chemical bond
can be deduced from the quantum theory, this gives us a very good plausible
reason for thinking that nature works in this way in mathematically intractable
cases. We can still hold, as he says, that ‘there are no autonomous
principles of chemistry that are simply independent truths, not resting on
deeper principles of physics’. 10
Having said that my reduction is ontological and not translational,
I am not sure that I am using ‘ontological’ in quite the way in which Haldane
is (see p. 84). The weight of the average plumber is definable as the sum
of the weights of plumbers divided by the number of plumbers. So talk of
the average plumber is translatable into talk of the plumbers. However, I do
not require translation for ontological reduction. I can still say that a tree is
nothing over and above a physical mechanism, just as a radio receiver is, even
though talk of a tree is not translatable into talk of electrons and protons.
If non-translatability implied non-naturalism, non-naturalism would be too
easily come by.
I would also suggest that Haldane’s term ‘explanatory reductionism’ is
not quite what I would mean by the term ‘reductionism’. Recall the matter of
some chemical reaction. One could explain it by purely chemical considerations
involving the chemical bonds of the molecules concerned. Nevertheless