I have been reading about the SMD results and it's "damning" nature for GET. My understanding of the result is as follows: price changes not only cause a substitution effect but also change the wealth distribution of a society. The latter could, in principle, cause the excess demand function to have any shape (save for homogeneity of degree zero, Walras' Law, boundary conditions, continuity)
My reaction to this is that it seems enormously unlikely. While I'm sure it's possible, it seems to me that if the number of individuals and commodities gets sufficiently large, that "hardly any" economies would actually exhibit this weird behaviour. The wealth redistributions required to get the weird shape would be just too improbable. I am curious if there was some way of defining the space of economies as a measure space, and then saying that the set of economies with weird aggregate excess demand function is of "small" measure (and tending to zero with the number of individuals/commodities). Do mathematical economists agree with this intuition of mine?