With such severe drawbacks, one might wonder why we have persisted
with our models based on the General Equilibrium approach. The idea
that the economy is essentially in an equilibrium state or on an equilibrium
path from which it is sometimes perturbed seems simply to be the wrong
departure point. I claim that we have to start from the vision of the economy
as a system of interacting agents whose actions, beliefs, and decisions
are constantly and mutually influenced. Such a system will self-organize
but there is no reason to believe that it will do so into something corresponding
to our notion of an equilibrium state and, even should it happen
to attain such a state, for the reasons that I have explained, it will not
necessarily remain there. It seems perverse to view economic agents as
isolated and only linked through an anonymous market. As I have
observed, most of the explanations for the current crisis involve a very
different view of the economy. The aggregate behaviour of large systems
of interactive individuals, molecules, or particles, which are widely studied
in other fields, is not typically that of an average or representative member
of the population. Again, the very interaction between the individuals
changes the aggregation problem and should make us aware of the fact
that major changes at the aggregate level can be provoked by small events
at the micro level. The fact that we have not done this seems to illustrate
a basic tendency in economic theory. As arguments that undermine the
models we have built arise, we simply make assumptions which are not justified theoretically but which, in effect, make the problems disappear.
We persist in clinging to the basic models and making them more mathematically
sophisticated whilst overlooking their fundamental flaws.
Curiously, it is only the observation of extraordinary empirical phenomena
which leads to the questioning of the models and, as Krugman (2009b)
has suggested, even this, may not lead to significant changes in the theory.
To illustrate this, I will take a look at the basic assumption which underlies
much of modern financial economics, the ‘efficient markets’ hypothesis
and suggest that we have witnessed very similar developments. That is,
economists have persisted with a model that is theoretically flawed and
systematically contradicted by the empirical evidence. Again a quick look
at the history of this concept is very revealing.