In his theory, John Maynard Keynes supported economic policy makers by his argument emphasizing their capability of macroeconomic fine-tuning. The only problem was that actual consumption time series were much less volatile than the predictions derived from the theory of Keynes. For Keynes, consumption expenditures are linked to disposable income by a parameter called the marginal propensity to consume. However, since the marginal propensity to consume itself is a function of income, it is also true that additional increases in disposable income lead to diminishing increases in consumption expenditures: in other words, the marginal propensity to consume has an inverse relation with real income. It must be stressed that the relation characterized by substantial stability links current consumption expenditures to current disposable income—and, on these grounds, a considerable leeway is provided for aggregate demand stimulation, since a change in income immediately results in a multiplied shift in aggregate demand (this is the essence of the Keynesian case of the multiplier effect). The same is true of tax cut policies. According to the basic theory of Keynes, governments are always capable of countercyclical fine-tuning of macroeconomic systems through demand management.