Reply to Haldane 167A naturalistically minded philosopher might concede that there might be no
simple cause – e.g. the firing of a neuron – but would find it mysterious that
the total neural state prior to the action together with its changes under
internal or external stimuli should not have to be the cause of the action.
The naturalist can even agree with Haldane that most action calls for no
explanation. Explanation is a highly contextual matter. Often the explana-
tion is not called for because it is too simple and obvious. If a person desires
to eat an apple and sees an apple on the plate it is not mysterious that the
apple should be eaten, and quite compatible with desire and perception being
neural states, processes or events. Furthermore, Haldane is right in saying
that causal explanation is often not needed because we know that we are
dealing with a rational animal. What we call for are not explanatory reasons
but justifying reasons. If you ask me why I make a certain inference I will
perhaps reply by citing the rule of modus tollens. But that an inference falls
under the rule in no way implies that it was not caused. It was caused partly
by my neural make-up having been trained to operate in accordance with the
rule of logic.
Nor need the naturalist disagree with Haldane in saying that ‘Action
differs from mere movement in being purposeful, in aiming to advance
an interest of the agent’ (see p. 145). The naturalist will, however, look to an
elucidation of purpose on the analogy of purposive mechanisms so familiar
in modern engineering. (Recall my remarks about intentionality earlier in
this Reply.) Purpose can be an explanans, but is not ultimate. It is also an
explanandumand Haldane needs to show that the explanation of purposive
activity cannot be a mechanistic one. This is because I hold to a variant of
Ockham’s razor, that mysteries should not be multiplied beyond necessity.
Haldane probably will agree with me here. Perhaps we differ on what we find
mysterious. Aristotelian teleology seems mysterious to me, but not to him.
This is a question on which the reader will have to make up his or her mind
on the basis of the general attractiveness or otherwise of our respective meta-
physical positions. I will, however, mention one thing that must be avoided.
We should not confuse ‘reason as cause’ with ‘reason as justification’. We
must distinguish ‘reason’ as cause, a sense in which a desire can be a reason,
and ‘reason’ as justification, where asking for a reason is asking for a logical or
moral rule, a missing premiss, or something like that. Rules and propositions
are not causes though our attitudes to them may be. Haldane is too acute a
philosopher to have fallen into this elementary confusion, but for ensuring
clarity in exposition and argument this possibility of confusion needs to be
mentioned.
I have found Haldane’s notion of voluntary action unclear, and unnecessary
for explaining the facts. Of course Haldane and I may differ as to what the
facts are that need explaining. Haldane says that human beings are ‘moved