Evolution in Mind by Henry Plotkin, Penguin, 拢25, ISBN
0713991380
PSYCHOLOGY needs evolution. This, says Henry Plotkin, head of University
College London鈥檚 psychology department, is the 鈥渟ingle, simple point鈥� of his
Evolution in Mind. But although his book claims to be an expression of
that 鈥渧igorous movement called evolutionary psychology鈥� it is far from attempts
to understand the workings of the mind with reference to evolved mental
tools.
Plotkin correctly condemns the 鈥渆xtraordinarily bankrupt stance of
behaviourism鈥� and points out that brains are not free to learn just any old
thing鈥攏ot only is general-purpose conditioning too weak a mechanism, but
organisms can鈥檛 afford to learn everything by trial and error. But unlike the
evolutionary psychologists, Plotkin argues that what the brain can learn is not
so much facilitated by genes as 鈥渃onstrained鈥� by them, claiming that evolution
has been adding constraints ever since 鈥渢he initial evolution of learning and
intelligence 500 million or more years ago鈥�. But he does not explain how this
approach solves the problems of conditioning, how these constraints are brought
to bear on learning, or how they account for the intricate design displayed by
the cognitive tools such as language.
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Above all, Plotkin won鈥檛 accept that his is a very different process from
that envisaged by the evolutionists he mentions favourably, such as Steven
Pinker and Simon Baron-Cohen, who see genes not as 鈥渃onstraining鈥� behaviour but
as the very things that make it possible.
A gene-centred account of human behaviour, argues Plotkin, must be false
because it relies on an unconscious 鈥渄rive鈥� to propagate one鈥檚 selfish genes.
But evolutionary psychologists would argue that genes get selected because they
are good at building things like arms, and in particular, because they built our
brains to respond to our ancestral environment in adaptive ways. Plotkin鈥檚
dilemma is that if evolutionary theory can be applied to human behaviour
directly, through brain construction, there is no need for the metaphorical
application he prefers: cultural evolution.
Plotkin has the notion that complex things, such as culture, require complex
theories to explain them. But he presents no evidence to support his claim that
culture evolves rather than just changes. The question of what might constitute
the 鈥渃ultural units鈥� of such an evolutionary process remains unresolved. And
there is no discussion of the selection pressures on these units. So cultural
evolution becomes just cultural transmission with a Darwinian gloss.
Evolutionary theory has more to offer the social sciences than this.