“There’s something wrong with everything. In macro; not, you know, in life.” That may not be a verbatim quotation, but I remember Tyler explaining this in PhD macro I, and it has stuck with me. You don’t really understand a school of macroeconomic thought until you can dispassionately evaluate both its strengths and weaknesses. If your answer is that it has no strengths, then you don’t understand it; lots of very smart people developed the theory for a reason. If your answer is that it has no weaknesses, then you don’t understand it; lots of very smart people disbelieve the theory for a reason.