I just read an interesting paper by Mark Fedyk on
evolutionary psychology (EP) (here).
The paper does a pair of things (i) it provides an accessible discussion of the
logic behind EP and (ii) it criticizes the massive modularity hypothesis (i.e.
the proposal that minds/brains consists of many domain specific modules shaped
by the environmental exigencies of the Pleistocene Epoch).[1]
Fedyk elucidates the logic of EP by discussing the relation
between “ultimate” and “proximate” explanations. The former “refer to the
historical conditions responsible for causally stabilizing a particular
phenotype (or range of phenotypes) in a population” (3). Such explanations try
to isolate “why a pattern of behavior was adaptive in an environment” however
it is not restricted to the mechanisms involved in fitting the phenotype with
the environment. These mechanisms are the province of “proximate” explanations.
These refer to the “psychological, physiological, neurophysiological,
biochemical, biophysical, etc. processes which occur at some point within the
course of an organism’s development and which are responsible for determining
some aspect of an organism’s phenotype” (3).
One of Fedyk’s main points is that there is a many-many
relation between ultimate and proximate explanations and, importantly, that
“knowing the correct ultimate explanation” need “provide no insight whatsoever”
into which particular proximate explanation is correct. And this is a problem
for the EP research program which aims to “offer a method for discovering human psychological traits”
(Fedyk quoting Machery)(5). Here’s how Fedyk summarizes the heuristic (6):
…the evolutionary psychologist
begins by finding a pattern of human behavior that in the EEA [environment of
evolutionary adaptedness, NH] should have been favored by selection. This is
sufficient to show that the patterns of behavior could have been an adaptation…Next, the evolutionary psychologist infers
that there is a psychological mechanism which is largely innate and
non-malleable, and which has the unique
computational function of producing the relevant pattern of behavior. Finally a
test for this mechanism is performed.
The first part of the paper argues that this logic is likely
to fail given the many-many relationship between ultimate and proximate
accounts.
In the second part of the paper, Fedyk considers a way of
salvaging this flawed logic and concludes that it won’t work. I leave the details
to you. What I found interesting is the discussion of how modern evolutionary
differs from the “more traditional neo-Darwinian picture.” The difference seems
to revolve on how to conceive of development. The traditional story seemed to
find little room for development save as the mechanism for (more or less)
directly expressing a trait. The modern view understands development to be very
environment sensitive capable of expressing many traits, only some of which are
realized in a particular environmental setting (i.e. many of which are not so
realized and may never be). Thus, an important difference between the
traditional and the modern view concerns the relation between a trait and the
capacities that express that trait. Traits and capacities are very closely tied
on the traditional view, but can be quite remote on the modern conception.
Fedyk discusses all of this using language that I found
misleading. For example, he runs together ‘innate,’ ‘hardwired’ and
‘malleable.’ What he seems to need, IMO, is the distinction between traits and
the capacities that they live on. His important observation is that the traits
are expressions of more general capacities and so seeing how the former change
may not tell you much about how (or even whether) the latter do. It is only if
you assume that traits are pretty direct reflections of the underlying
capacities ( i.e. as Fedyk puts it (15): if you assume that “each of these
modules is largely hardwired with specific programs which must cause specific
behavioral patterns in response to specific environmental conditions…”) that
you get a lever from traits to psychological mechanisms.
None of this should strike a linguist as controversial. For
example, we regularly distinguish a person’s grammatical capacities from the
actual linguistic utterances produced. Gs are not corpora or (statistical)
summaries of corpora. Similary, UG is not a (statistical) summary of properties
of Gs. Gs are capacities that are expressed in utterances and other forms of
behavior. UG is a capacity whose properties delimit the class of Gs. In both
cases there is a considerable distance between what you “see” and the capacity
that underlies what you “see.” The modern conception of evolution that Fedyk
outlines is quite congenial to this picture. Both understand that the name of
the game is to find and describe these capacities, and that traits/behavior are
clues, but ones that must be treated gingerly.
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