Much of the modern complexity movement in economics is stimulated by the use of more current models out of physics, especially those drawing on statistical mechanics. These are especially useful for studying systems with heterogeneous interacting agents. The approach is generally not to prove theorems in a Bourbakist manner, but to engage in simulations or to try to fit various data from financial markets (notorious for their non-normal fat tails in returns) or income or wealth or firm size distributions to various models that come out of physics and generate power law distributions. Not sure if Deirdre approves of this sort of thing or not, but it is not Bourbakist, and the econometrics is usually not so oriented to stat significance. Much of this work is actually being done by physicists, now part of the so-called "econophysics" movement, although sometimes the ignorance of economics by these people can be annoying, especially when they start intoning about how they have solved all the problems of economics, when they have not read much literature and are talking about non-problems, although there seems to be less of this sort of thing going on these days. Barkley Rosser