Some microeconomists may regard the ‘economic world’ a model of the whole
world – Gary Becker comes to mind^61 – but most are ‘content to make theoretical
assumptions’ (Keohane’s words) that are based on, or result in, a more limited model.
Waltz was clearly not troubled by microeconomic theory’s unrealistic assumptions,
or by his own analogous assumptions. For Keohane, erecting a model based on
unrealistic assumptions runs against ‘accepted practice’. For Waltz, doing so is an
accepted practice – one, he might have said, that Milton Friedman (whose ghost
Keohane, no doubt insincerely, sought to pacify) authoritatively sanctioned.
Friedman’s position hardly seems inflammatory. He wrote:
More generally a hypothesis or theory consists of an assertion that certain
forces are, and by implication others are not, important for a particular class
of phenomena and a specification of the manner of action of the forces it
asserts to be important. We can regard the hypothesis as consisting of two
parts: first a conceptual world or abstract model simpler than the ‘real world’
and containing only the forces that the hypothesis asserts to be important;
second a set of rules defining a class of phenomena for which ‘the model’ can
be taken to be an adequate representation of the ‘real world’ and specifying
the correspondence between the variables or entities in the model and
observable phenomena.^62As I suggested earlier, Friedman was a strong positivist; only ‘observable phenomena’
count for empirical purposes. He acknowledged the competing tendencies of
rationalism and empiricism in Western philosophy by discriminating clearly between
conceptual worlds and the real world. He implied that anyone schooled in science
would be concerned about the correspondence between the model’s elements and
that part of the world to which it presumably refers. The only trouble then would
seem to be the dissonance between Wendt’s proposition 2 – theories should refer
to a real world available to the senses – and Friedman’s view that ‘a theory cannot
possibly be thoroughly “realistic” in the immediate descriptive sense so often
assigned to this term’.^63
Indeed the trouble here is not the unreality of Friedman’s and Waltz’s models.
The source of trouble is the notion of correspondencebetween the model and the
world. At least for Friedman and Waltz, correspondence is a loose criterion for
deciding on theoretical assumptions and building models. Furthermore, it does not
tell you how to negotiate between theory and reality, such as it is. Waltz turned to
figurative language in explaining this process. ‘You take the theory’, he remarked
in an interview, ‘and then you have to hook it up to the real world’.^64 While
his implicit model of the process would seem to require a great deal more than
sensory experience, his language suggests that he has not fully considered what this
might be.
By contrast, Keohane as an empirical realist and Kurki as a philosophical realist
have assumed that we all have some kind of access to an independently real world.
As informed observers, theorists know what is real because what they know reflects
Structure? What structure? 99