Consistency and stability analysis of models of a monetary growth imperative

Abstract. Several authors, particularly from ecological economics, locate a ‘growth imperative’ within the current monetary system based on credit money and positive interest rates. The strongest claim comes from papers such as Binswanger (2009, 2015) arguing based on a monetary circuit model that growth is unavoidable to maintain economic stability independent on the will of the economic agents. On the other side of the spectrum, Jackson & Victor (2015) have disputed this claim, presenting a post-Keynesian stock-flow consistent model that converges to a stationary state in their numerical simulations.

The central aim of this paper is to clarify why certain modeling approaches lead to a growth imperative and others do not. We analyzed the models in the tradition of Binswanger and concluded that their accounting of banks’ capital is inconsistent, and a modeling assumption central for a growth imperative is not underpinned theoretically: Bank’s equity capital has to increase even if debt does not. This is a discrepancy between the authors’ intentions in their texts and their actual models.

Second, we analyze several post-Keynesian models, a single static one, and four discrete time stock-flow consistent models. We show how to perform a stability analysis in the parameter space, and find that depending on parameter values, the stationary state can be stable or not. A stationary state with zero net saving and investment can be reached with positive interest rates, if the parameter ‘consumption out of wealth’ is above a threshold that rises with the interest rate.

We conclude that a monetary system based on interest-bearing debt-money with private banks does not lead to an ‘inherent’ growth imperative, but the stationary state can be unstable. This is caused by agents’ decisions, not by structural inevitableness. The stability analysis adds additional insights to numerical simulations of the dynamics, because we can precisely determine the parameter ranges where a stationary state can be reached.

Oliver Richters, Andreas Siemoneit (2017) Consistency and stability analysis of models of a monetary growth imperative”, Ecological Economics, vol. 136, pp. 114-125

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