Production is not a measure of aggregate demand and no-one doing econometrics that I know takes Say's law seriously. Keynes pointed out some of the problems with it oddly enough, but to my knowledge he did NOT propose a "Calc 1 model", although I agree it would be worth looking at if he did.
If aggregate demand were anywhere near the point of full employment, we would see evidence of inflation. We do not. Some prices are rising in nominal terms as the dollar depreciates, but that is quite different.
If aggregate demand were anywhere near the point of full employment, we would see evidence of inflation. We do not. Some prices are rising in nominal terms as the dollar depreciates, but that is quite different.