We propose a microeconomic foundation of the multiplier effect and that of the consumption function using a dynamic optimization model that explains a shortage of aggregate demand and unemployment. We show that government purchases boost aggregate demand through a multiplier-like process but...

Although the Keynesian multiplier effect of public works is criticized for lack of a microeconomic foundation, it is still taught in most undergraduate courses and believed to be useful for policy makers. However, it has a serious fallacy even if we accept the consumption function. This note...