Also, I was inspired to do this because of Noah Smith's recent post on why macroeconomics doesn't seem to work very well. Put simply: there is limited empirical information to choose between alternatives. My plan is to produce an economic framework that captures at least a rich subset of the phenomena in a sufficiently rigorous way that it could be used to eliminate alternatives. In a sense, supply and demand is used as a heuristic to do this in economics today. If your model seems inconsistent with supply and demand, you'd better have a good, rigorous reason.