As a Phd student, I really got the impression that really neoclassical economic models boil down to a zero-sum trade-off between saving and consumption, where saving is tacitly treated as automatically implying investment. This is suggested by Keynes's formulas as well. Thus, what is not consumed, is saved, and what is saved, is invested.
You seem to have forgotten that the Keynesian and [neo]"classical" views are totally incompatible: the latter view savings and investment as equal *ex ante* (meaning that every decision to save is necessarily accompanied by an equivalent decision to invest and vice-versa) while for Keynes investment and savings decisions are quite independent of each other. That aggregate savings and aggregate investment are equal *ex post* is merely an accounting identity. What counts is the quantity. If at a given level of income intended savings exceed investment, their identity is established by falling income and employment, and conversely if investment exceeds intended saving the identity is established at a higher level of income and employment. For Keynes, as for Marx, it is investment that is the dynamic factor--and expected profitabilty that drives investment.
Shane Mage
"When we read on a printed page the doctrine of Pythagoras that all things are made of numbers, it seems mystical, mystifying, even downright silly.
When we read on a computer screen the doctrine of Pythagoras that all things are made of numbers, it seems self-evidently true." (N. Weiner)
