250 Tim Lewens
(2005: 70). If we assume that all individuals in a population have a psychology that dis-
poses them to fi nd frequently encountered technologies especially attractive, then we can
predict that various phenomena will emerge at the level of a population made up of such
individuals. Specifi cally we can predict that the rate of uptake of a new technology mea-
sured across the population as a whole will increase over time. To show why this is the
case requires some (admittedly very elementary) mathematical thinking. As the frequency
of individuals using the technique increases, so the attractiveness of the technology to a
typical individual increases, and the chance of a new individual adopting the technique
increases. Elementary population thinking enables us to explain why technology adoption
in a population follows the so-called S-curve.
14.6 Sober’s Challenge
Elliott Sober is somewhat skeptical of the value of models of cultural evolution (Sober
1992). Sober says that sociologists are interested by and large in questions about what
makes one technology, for example, more attractive to the typical individual than another.
One wants to know not just whether RollerbladesTM are more attractive to users than roller
skates, but why they are more attractive. Evolutionary models of cultural change rarely
promise answers to these questions. Evolutionary models do, on the other hand, give us
rules for determining what will happen at the population level once we have determined
which technology is the more attractive one. But Sober’s complaint is that in many cases
this sort of calculation is too obvious to be of much value. Once we know that Rollerblades
are more attractive than roller skates, we can infer that Rollerblades will replace roller
skates.
Boyd and Richerson respond by saying that Sober’s objection assumes that “we are all
good intuitive population thinkers” (Richerson and Boyd 2005: 97). Sober assumes that
it is obvious how individual-level dispositions to prefer one cultural variant to another will
combine to yield population-level phenomena. We should concede to Boyd and Richerson
that, on occasions, naïve population thinking might let us down. It is perhaps not imme-
diately obvious that a shared psychological disposition to adopt the most frequently
encountered technique will lead to an S-shaped curve describing the adoption of new
technology across the population. Other ways of determining how individual-level psy-
chological dispositions will play out at the population level are even less intuitive.
Boyd and Richerson’s appeal to population thinking in defense of cultural evolutionary
models is legitimate. Indeed the same defense was put forward by Sober in the very paper
they criticize:
So the question about the usefulness of these models of cultural evolution to the day-to-day research
of social scientists comes to this: Are social scientists good at intuitive population thinking? If they
are, then their explanations will not be undermined by precise models of cultural evolution. If they