Why macroeconomics does not supervene on microeconomics

In recent years, the project of providing microeconomic foundations for macroeconomics has taken on new urgency. Some philosophers and economists have challenged the project, both for the way economists actually approach microfoundations and for more general anti-reductionist reasons. Reductionists and anti-reductionists alike, however, have taken it to be trivial that the macroeconomic facts are exhaustively determined by microeconomic ones. In this paper, I challenge this supposed triviality. I argue that macroeconomic properties do not even globally supervene on microeconomic ones. This is simply a consequence of the difference in the explanatory goals of the respective fields, which implicitly carve out the microeconomic property set in such a way that it underdetermines macroeconomic properties. It means, however, that microeconomics-based foundations for macroeconomics are inadequate in principle.