“There is some evidence related to hysteresis for what I called a Reverse Says Law —lack of demand creates its own lack of supply down the road in terms of productivity growth. But if one was attempting to synthesize everything rather than to push a very important aspect of a phenomenon that had received too little attention, I think integrating exogenous developments on the supply side would be worthwhile.”“Some people would say it’s really all the supply side, and you’re all about the demand side. We’ve had a big productivity slowdown and isn’t that the right thing for you to think about, and I think there’s obviously something to that. The point I’d make about that is that, in general, we have a way of telling the difference between supply shocks and demand shocks, which is that supply shocks raise prices and demand shocks lower prices. The general tendency to low inflation coincident with low quantity guides you a little more towards the demand-shock view therefore then the supply-shock view.