Innovation and Population 251
are not, then social scientists should correct their explanations (and the intuitions on which they
rely) by studying these models. (Sober 1992: 492)
An example of an area where the intuition of a prominent social scientist has been chal-
lenged by this form of population thinking comes from Nelson and Winter’s work in eco-
nomics. Why think that fi rms act as effi cient profi t maximizers? Because, says Milton
Friedman, if they did not do so, they would not have survived (Nelson and Winter 1982:
140). This form of intuitive evolutionary argument is no supplement for a population-level
model, which asks under what circumstances only the effi cient profi t-maximizing fi rms
will survive, and under what circumstances a population comprising a signifi cant propor-
tion of nonmaximizers could persist. Nelson and Winter claim that their more rigorous
models show Friedman’s argument to be fl awed, or at least grossly oversimplifi ed (Nelson
and Winter 1982: 141).
14.7 Population and Innovation
Let me now turn more directly to the question of population thinking and innovation. The
questions we need to keep in mind from here onward—the questions prompted by Sober’s
challenge—are not only whether population thinking yields hypotheses that are true but
whether population thinking has enough heuristic value to yield hypotheses that one might
not otherwise think to test. Simple demographic facts relating to such things as the size
of a population can affect the likelihood of innovation being produced in that population.
This of course is hardly a surprising outcome of formal modeling. The result was intuitive
enough for Darwin to have noted it both in the case of organic evolution, and in the case
of technical change. In The Origin of Species he remarks:
as variations manifestly useful or pleasing to man appear only occasionally, the chance of their
appearance will be much increased by a large number of individuals being kept; and hence this
comes to be of the highest importance to success. (Darwin 1985 [1859]: 41)
Darwin makes a related point in his discussion of technical innovation in The Descent of
Man:
[I]f some one man in a tribe, more sagacious than the others, invented a new snare or weapon... the
plainest self-interest, without the assistance of much reasoning power, would prompt the other
members to imitate him; and all would thus profi t.... If the new invention were an important one,
the tribe would increase in number, spread, and supplant other tribes.... In a tribe thus rendered
more numerous there would always be a rather greater chance of the birth of other superior and
inventive members. (Darwin 2004 [1877]: 154)
If an important invention renders a tribe more numerous, the invention thereby increases
the chances, merely by increasing the size of the tribe, of inventive members being
born into that tribe, and producing yet more inventions. This result may be intuitive but