The effective demand problem and the structural change problem are economic
causes of unemployment. But Post Keynesians such as Kalecki have noted that there
may also be political obstacles to full employment. Since unemployment in Keynes is a
negative by-product of capitalism, it is viewed as serving no purpose in the capitalist
system and so is clearly undesirable for all. Kalecki, Steindl, and others, however, have
highlighted that unemployment may be functional in capitalism, an insight that is drawn
from Marx’s analysis of the reserve army of labour.