Reply to Haldane 165of the proper function of an organ of an animal or plant. I said that it was
often useful for a biologist, who is wondering about hypotheses of biological
mechanism, to think in an ‘as if ’ way of purpose since natural selection sees
to it that organs are by and large conducive to the survival of the organism.
Alternatively, function may be defined in terms of ‘what something (e.g. an
organ) is selected for’ (see p. 169, n. 7). There is no reference to actual
purposive design or Aristotelian function.
Dogs do not have as acute vision as we do. A much larger part of the cortex
of a dog is devoted to processing the sense of smell than is the case with
humans. So perhaps in a way it is part of the function of a dog’s vision to be
weak: it leaves room in the cortex for the sense of smell that is so important
in doggy existence. Still, this is stretching even the biologist’s ‘as if ’ notion of
a function a bit far.
These remarks are just hints towards a possible appreciation of some of
the difficulties in the way of an Aristotelian notion of ‘function’. Perhaps in
the end they are quibbles which Haldane may be able to accommodate to
his notions.
Suppose that you are suffering from a violent toothache. Does this seem
like a privation of good and not something positively horrible? Perhaps the
pain is good as a means – it alerts one to the necessity of not chewing on
the tooth. (Before dentists nothing much could indeed be done! So it is not
all that easy to state what avoiding or remedial action natural selection has in
this case operated to promote.) One might wonder why an omnipotent God
could not have fixed the laws of nature and even the course of evolution so
that more pleasant signalling systems might have existed.
Mice obviously do not like being eaten by cats. However according to
Haldane God does not create this evil. What he did was create an interacting
system of cats and mice in which the well-being of the cats is secured at the
expense of the mice (see p. 139). ‘Where there is a bad there is a good
involving the realization of the powers and liabilities of interacting systems’,
says Haldane. Well, given the laws of nature maximized self-realization could
perhaps come about in this way. But could not God have created a universe
with different laws, non-metabolizing non-competitive spirits, all engaged in
satisfying non-competitive activities such as pure mathematics or the pro-
duction of poetry? Perhaps Haldane could concede that this might be a good
and even better universe than ours (with its cats and mice, etc.) but go on to
say that provided the cat and mouse universe is good on balance why not
create it also? In the spirit of Leibniz we could say that the more universes the
better, so long as none are on balance bad.
If one accepted this, one need not indeed suppose that evil is always a mere
privation of good. A positive balance of good and bad would be enough.
One’s reluctance to accept this is due to the thought that if God is able to