رشد اقتصادی با مصرف معیشتی

Four stylized facts of economic growth in DCs are set up initially. Despite its obvious simplicity the linear growth model with subsistence consumption is able to reproduce two of them: a rise in the saving rate along with per capita income as well as β-divergence. The rate of convergence shows extraordinarily low values at early stages of economic development. Hence, the big diversity in growth rates can partly be explained to represent transitional phenomena. An extension of the basic model additionally allows an explanation of the hump-shaped pattern of growth.

If one takes Gersovitz (1988) literally and is interested in an explanation of economic growth and development in terms of growth theory, one is led to ask what class of growth models is consistent with this view. In addition, it is reasonable to ask what class of growth models is able to reproduce the main stylized facts of (aggregate) economic growth primarily applying to the lower range of per capita income:1 1. A big diversity in the growth rates of per capita income including zero and even negative growth;2 2. a positive correlation between the saving rate and per capita income;3 and 3. a positive correlation between the growth rate and the level of per capita income, i.e. β-divergence.4 4. More generally, many authors report β-divergence for the lower range of per capita income and β-convergence for the upper range of per capita income, i.e. a hump-shaped pattern of growth.5 Beside an increase in total factor productivity, the accumulation of reproducible inputs (physical and human capital) represents one of the major forces of growth. Especially in the long run, the accumulation of physical and human capital needs to be financed by internal saving.6 Within the development literature it is stressed that saving in the case of developing countries (DCs) is determined by the willingness as well as the ability to save (e.g., Hemmer, 1988, pp. 150–159). The usual constant-intertemporal-elasticity-of-substitution (CIES) formulation of preferences abstracts from the requirement of a minimum consumption level in order to sustain life. However, the requirement of subsistence consumption undoubtedly restricts the possibilities to substitute consumption intertemporally and hence the ability to save at least for the lower range of income. Several questions arise which are of fundamental importance: Does the requirement of subsistence consumption influence the process of growth beyond this threshold? If so, how long does it take for the influence of subsistence consumption on growth to vanish? How does the requirement of subsistence consumption interact with other essential mechanisms of growth? The paper in hand seeks to answer these questions systematically within the context of simple endogenous growth models with Stone–Geary preferences. In addition, it will be shown that these models provide a potential explanation of the stylized facts listed above. It is assumed that the economy under study is symmetric to the rest of the world with respect to preferences and technology. As Rebelo (1992) stresses, the aim of this methodological assumption is to rule out explanations of differences in growth experiences that are based solely on the existence of cross-country differences in preferences and technology. In order to address very specific theoretical as well as empirical questions, Stone–Geary preferences (henceforth SGP) have been widely applied within recent growth literature. According to Rebelo (1992), a broad class of endogenous growth models is inconsistent with cross-country diversity in growth rates in the face of international capital markets. As a solution to this theoretical problem, he suggests a linear growth model with SGP. Easterly (1994) uses a constant-elasticity-of-substitution production function with the Jones–Manuelli property and SGP to discuss the threshold effects of different policy measures on the long-run growth rates. Ben-David (1994) applies a neoclassical growth framework extended by subsistence consumption to demonstrate the possibility of multiple balanced-growth equilibria. The paper is organized as follows: Section 2 concisely discusses the concept of subsistence and its empirical importance. In Section 3 a linear growth model with SGP is analyzed systematically. The quantitative convergence implications are investigated in addition to the qualitative convergence implication. In Section 4 the basic model is extended by diminishing marginal returns to capital as well as by the general meaning of policy-induced distortions. Section 5 summarizes and concludes with some final considerations.

The requirement of subsistence consumption unambiguously affects the process of economic growth. It clearly restricts the ability to save not only for levels of per capita income at or slightly above subsistence. The intertemporal elasticity of substitution, which reflects both the ability and the willingness to save, increases with the level of per capita consumption and asymptotically converges to a constant. As a result, the requirement of subsistence consumption causes the growth rate of income to increase. It therefore represents an important mechanism of β-divergence, which might be labeled as subsistence-divergence mechanism. For realistic and widely employed parameter values, the rate of convergence is exceptionally low at early stages of economic development and the time span required for the transition towards the asymptotic balanced-growth equilibrium is correspondingly long. Despite its obvious simplicity, the linear growth model with subsistence consumption is able to reproduce two of the stylized facts enumerated in the Introduction. The model implies a rise in the saving rate along with the level of per capita income [stylized fact (2)] as well as β-divergence [stylized fact (3)]. On account of the extraordinarily low values of the rate of convergence for low incomes, different growth rates can partly be explained to represent transitional phenomena [stylized fact (1)]. However, if international symmetry with respect to preferences and technology is supposed, the possible range of growth rates is restricted. Hence, the linear growth model with subsistence consumption has some difficulty in explaining the big diversity in growth experiences observable for the group of DCs. In addition, the model clearly fails to reproduce the hump-shaped pattern of growth [stylized fact (4)]. An extension of the basic model by a general index of policy-induced distortions, which is sensibly allowed to vary internationally, permits a more satisfactory explanation of stylized fact (1). The possible range of long-run growth rates enhances despite maintaining the symmetry assumption. In the case of unbounded growth one observes policy continuity, i.e. the growth rate falls steadily as the extent of distortions increases (Jones and Manuelli, 1990). The model is further extended by diminishing marginal returns to the factors that can be accumulated in order to reproduce the remaining stylized fact (4). The interaction between the subsistence-divergence mechanism and the neoclassical convergence mechanism produces an acceleration subsequently followed by a deceleration of growth, i.e. a hump-shaped pattern of growth [stylized fact (4)].