Here's
the gist. Plantinga
argues that if naturalism and evolution are true, then semantic
epiphenomenalism is very probably true - that's to say, the content of
our beliefs does not causally impinge on our behaviour. And if
semantic properties such as having such-and-such content or being true
cannot causally impinge on behaviour, then they cannot be selected for
by unguided evolution. Plantinga's argument requires, crucially, that there be no
conceptual links between belief content and behaviour of a sort that
it's actually very plausible to suppose exist (note that to suppose
there are such conceptual links is not necessarily to suppose that content can be exhaustively
captured in terms of behaviour or functional role, etc. in the way
logical behaviourists or functionalists suppose). It turns out that if
such conceptual links exist, then (rather surprisingly!) natural selection will favour true belief even if belief content is epiphenomenal. So Plantinga is mistaken: even if belief content has no causal impact on behaviour, natural selection can still
select for true belief. The EAAN is therefore refuted. To resurrect the
EAAN, Plantinga would need to show that there are no conceptual links of
the sort I envisage between content and behaviour, links of a sort that,
as I say, do seem to exist.
NATURALISM, EVOLUTION AND TRUE BELIEF
Stephen Law
Plantinga’s
evolutionary argument against naturalism (EAAN) is currently one of the most
widely discussed arguments targeting philosophical naturalism (see, for
example, Beilby 2002). Plantinga aims to show that naturalism, in
combination with evolutionary theory, is, as he puts it, ‘incoherent or
self-defeating’. His argument turns crucially on the claim that, in the absence
of any God-like being to guide the process, natural selection is unlikely to favour
true belief. This, Plantinga supposes, is because natural selection selects
only for adaptive behaviour. It is irrelevant, from the point of view of
unguided evolution, whether the beliefs that happen to cause that adaptive
behaviour are true.