So far the attempts to defend the meaningfulness of the AD curve (Fred Foldvary, Kevin Hoover, and George Horwich) have depended upon the fact that the curve has been derived from the IS-LM model. What if we come to realize that the IS-LM model itself is not a legitimate or reliable framework with which to analyze the macro economy? For example, why would the IS curve (for a closed economy) shift rightward when government spending increases? Note that whatever the government spends, it must take from the public through taxes or borrowing. Or why would the IS curve shift rightward when investment spending increases? Note again that investors rely on the public's savings (borrowing from banks, issuing stocks or bonds/corporate paper). Even retained earnings belong to the public (shareholders), just as are depreciation funds. And why would the IS curve be expected to shift leftward when savings increase? Note that savings are spent; they are not the equivalent of hoarding, as the classics have taught us. Now if you can't shift the IS curve from any of the above episodes, it seems to me that the so-called AD curve is stuck in neutral or "dead in the water." I would think that historians of economic thought know where all this IS-LM mess came from -- the attempt to avoid the implications of the classical quantity theory of money as the legitimate explanation of price level determination (J.M. Keynes), not aggregate supply and aggregate demand. I can appreciate the frustrations of Alan Blinder (AER May 1997) when he writes that "30 years after Hicks, the IS curve stills needs work ... While the LM curve has collapsed in recent years, and key aspects of the IS curve are still in dispute" and David Romer (JEP 2000) who seeks to do "Keynesian Macroeconomics without the LM Curve." The failure of historians of economic thought (who are also textbook writers) to help put this theoretical fraud to rest baffles me. David Colander came close but stops short with: "But IS/LM is a model of goods/money market equilibrium--so what one gets from that derivation is a goods market equilibrium curve, not an aggregate demand curve. However, then, in AS/AD analysis, one adds an AS curve, and talks about disequilibrium as well as equilibrium.Yes, the math for the equilibrium points can work out, but the discussion of disequilibrium adjustment forces in the texts is generally problematic, if not downright wrong." I'm enjoying Robert Leeson's help in burying this MADD analysis with the AD. James Ahiakpor