A Mathematical Model of MMT (Modern Monetary Theory) with Profit Return

Even in perfect competition there is a positive profit return if the good is produced with decreasing returns to scale technology. Using a two-periods overlapping generations (OLG) model with production under perfect competition with decreasing returns to scale technology in which the economy grows by technological progress and the older generation consumers receive the profit returns, we consider the problem of budget deficit under economic growth. We will show the following results. 1) We need a budget deficit to achieve full employment under constant price when the economy grows by technological progress. 2) If the budget deficit exceeds the level necessary to maintain full employment in a growing economy under constant price, inflation will be triggered. We need a stable budget deficit to prevent further inflation. 3) If the budget deficit is insufficient to maintain full employment, it will cause a recession with involuntary unemployment. We can overcome a recession and restore full employment caused by insufficient budget deficit by a budget deficit larger than the one necessary and sufficient to maintain full employment without a recession. We should not offset the deficit created to overcome the recession by subsequent surpluses because we can maintain full employment through constant budget deficits. Also, we show that in each case the budget deficit equals the difference between the net savings of the younger generation consumers and that of the older generation consumers.