Growth Rate and Level Effects, the Stability of the Adjustment of Capacity to Demand and the Sraffian Supermultiplier

The paper presents a simple but complete formal version of the Sraffian supermultiplier model in which (i) growth is led by the autonomous components of demand that do not create capacity; (ii) private productive investment is an induced expenditure; and (iii) income distribution is exogenous. We show that the main results of the long-period and fully adjusted versions of the model in terms of growth rate and level effects are quite similar and therefore that such results in no way require the full adjustment of capacity to demand. We then analyze a simple set of sufficient dynamic local stability conditions that allow the long-period positions to gravitate towards the fully adjusted position in which capacity is adjusted to demand and that also provide the upper limit to demand-led growth paths. Finally, we show how some critics of the model have misinterpreted it as being supply-led and how this has led to a further confusion between the analysis of the tendency towards a constant value of the capacity-saving-determined warranted rate of growth and the proper stability analysis of the opposite process of adjusting capacity to demand (which tends to adjust the warranted rate endogenously to the growth rate of autonomous demand).