A DISTINCTION is drawn in economics between demand-constrained systems and resource-constrained systems (which for simplicity and symmetry we shall call supply-constrained systems). In the former, an increase in output can occur if there is a rise in aggregate demand without causing any scarcity-induced inflation; in the latter, output is constrained either by capacity being fully used up, or by the scarcity of some critical input or of foodgrains or of the labour force, so that a rise in aggregate demand, instead of raising output, simply causes scarcity-induced inflation.