Actions are a subclass of human behaviours which are distinguished, on
a modest view, by certain antecedent mental and neural processes and
events, including desires and beliefs. Libertarian philosophies have t
aken a less modest view, according to which some actions come under th
e influence of individual persons in a way distinct from being the nec
essary effect of a sequence of psychoneural events. Determinism claims
necessary connections between sequences of events and conditions, inc
luding those sequences that involve desires and beliefs and subsequent
actions. Even if a certain interpretation of modern physics shows det
erminism to be false, the sense of personal influence over action whic
h libertarians have remains obscure. It is not enlightened by the phys
icist's idea of inexplicable fluctuations between courses of events wi
th greater or lesser probabilities. If libertarianism remains obscure,
so do the grounds for an approach to explaining behaviour which might
be called ''explanatory individualism''. According to the latter stan
ce, the local outcomes of actions and larger social tendencies are onl
y properly explained in terms of the choices of individuals, rather th
an, for example, their neural or environmental antecedents. Again, bar
e indeterminism will not help to supply the required grounds. A more j
ustifiable stance is ''explanatory pluralism'', a doctrine which denie
s the intrinsic priority of individualistic modes of explanation over
those which focus on psychoneural, environmental, social or genetic co
nditions. It is stressed that on a sensible pluralism, any determinism
which correctly describes the history of actions would be no more ''g
enetic'', than indeterminism could be ''individualistic''. (C) 1997 El
sevier Science Ltd.