Steve Keen discusses DSGE modeling and microfoundations by asking the question if it is ideologically possible to derive macroeconomics from microeconomics. Using the example of the Sonnenschein–Mantel–Debreu theorem, Keen argues that on each level there are new complexities which can't be entirely derived from the level below. Hence, according to Keen, economics mustn't be about equilibrium but about permanent desequilibrium in order to account for economic complexity and dynamics.