The post-Keynesian tradition contains two different models of long-run growth in open economies -- the model of export-led cumulative causation (ELCC) originally conceived by Nicholas Kaldor and the model of balance-of-payments-constrained growth (BPCG) developed by A.P. Thirlwall. These models diverge significantly in their core underlying assumptions. For example, they disagree about whether long-term gains in relative price competitiveness are possible and whether import demand constrains long-run growth. The two modeling approaches also yield conflicting policy implications. For example, some ELCC models imply that a domestic demand stimulus can boost long-run growth by sparking a virtuous circle of cumulative causation (including an endogenous increase in productivity growth), while most BPCG models imply that only policies that raise the income elasticity of export demand or lower the income elasticity of import demand can permit faster growth in the long run. The fact that both models have found econometric support suggests that each contains empirically supported elements, but the tests that have been conducted to date have not had sufficient power to distinguish between them. This paper will present both models in a common analytical framework to compare their theoretical differences and policy implications. The paper will argue that a generalized BPCG model that allows for financial flows and relative price effects can incorporate the cumulative causation feedbacks from the ELCC approach while also imposing the balance of payments equilibrium condition that is missing from the latter. The paper will also explore under what conditions different versions of the models apply.
