The devaluation of money.
According to Keynesian theory, some microeconomic-level actions – if taken collectively by a large proportion of individuals and firms – can lead to inefficient aggregate macroeconomicoutcomes, where the economy operates below its potential output and growth rate. Such a situation had previously been referred to by classical economists as a general glut. There was disagreement among classical economists (some of whom believed in Say's Law – that "supply creates its own demand"), on whether a general glut was possible. Keynes contended that a general glut would occur when aggregate demand for goods were insufficient, leading to an economic downturn with unnecessarily high unemployment and losses of potential output. In such a situation, government policies could be used to increase aggregate demand, thus increasing economic activity and reducing unemployment and deflation.