Aggregate demand

*noun*; a concept central to the idea of Keynesian economics. Under this theory, business cycles (recessions, depressions, booms, recoveries) are caused by a failure of total demand across the entire economy to match total output. Aggregate demand is not merely influenced by people's ability to buy what they produce; it is also influenced by the marginal propensity to consume (MPC). If the MPC is less than 1, then an increase in national income will be matched by a smaller increase in aggregate demand, causing unemployment to rise and prices to fall.