رشد و امنیت اجتماعی: نقش سرمایه انسانی

This paper studies the growth and efficiency effects of pay-as-you-go financed social security when human capital is the engine of growth. Employing a variant of the Lucas model [Lucas, R.E., 1988. On the mechanics of economic development. Journal of Monetary Economics 22, 3–42.] with overlapping generations, it is shown that a properly designed, unfunded social security system leads to higher output growth than a fully funded one. Furthermore, the economy with an unfunded social security is efficient, while the other one is not. These results stand in sharp contrast to those obtained in models where the reason for economic growth is physical capital accumulation.

Various authors have shown that unfunded social security stunts economic growth in Romer (1986)-type endogenous growth models (e.g. see, Saint-Paul, 1992 and Wiedmer, 1996). The economic mechanism behind this result is straightforward. Unfunded social security discourages individuals from saving privately for old age, without compensating for this via forced public savings. As economic growth is positively related to the aggregate capital stock and hence, total savings, an economy with unfunded social security exhibits slower growth. A corollary of this statement is that the introduction of a pay-as-you-go pension system cannot lead to a Pareto-improvement as the decline in growth rates harms future generations. Economic growth need not, however, be due solely to physical capital accumulation as in Romer (1986). There is another strand of literature pioneered by Lucas (1988) that identifies human capital accumulation as the engine of growth. Once the effects of human capital are taken into account, the relation between social security and growth can appear in a completely different light. Employing a variant of the Lucas (1988) model with overlapping generations, we show that a properly designed, unfunded social security system leads to higher output growth than a fully funded one. Moreover, a competitive economy with such an unfunded social security system is efficient, whereas an economy without any or with a fully funded social security system is not. The reason for the inefficiency is the following. In Lucas (1988), growth is driven by the ability of human capital per worker to increase without bound, but since in an overlapping generations model individual human capital depreciates fully with retirement, any accumulation of human capital over time requires that succeeding generations inherit some part of the human capital stock of their ancestors. This implies a positive effect of actual investment in human capital on the productivity of future generations. This positive effect is, however, disregarded by every single individual, since it only has a negligible impact on the average human capital stock that is transferred to succeeding generations. In contrast, an unfunded social security program in which the size of the transfers to a particular old individual is properly tied to his human capital, renders the competitive allocation efficient by providing socially optimal incentives to invest in human capital. We show that this can be accomplished by a pension formula that displays some stylized features of the German pension system. The higher human capital investment under this scheme translates into faster output growth. The plan of the paper is as follows. Section 2 presents the economy without or with a fully funded pension scheme and establishes its inefficiency. In Section 3, an unfunded social security system is introduced and its impact on efficiency and growth is derived. Section 4 concludes.

We have shown that the connection between social security, economic growth and efficiency may take on a different or even a reverse form than that suggested by the recent literature if human, rather than physical capital accumulation is the engine of growth. In our model, a higher growth rate can be attained by employing a properly designed unfunded social security system which internalizes intergenerational spillovers of human capital formation. Furthermore, this internalization leads to an efficient allocation, while a laissez-faire economy generally fails to achieve efficiency. Although we have carried out our analysis in a model that sustains long-run growth, our (in-)efficiency conclusion would also hold in models that are more in the neoclassical tradition, provided that there is some human capital transmitted from generation to generation. Only if every generation were to “reinvent the wheel”, would the type of intergenerational externalities we investigate here, not exist. A positive effect of unfunded social security on human capital investment has also been derived by Sinn (1998). His approach differs from ours in some important respects. First, Sinn's case for social security rests on an intrafamily moral hazard problem, namely that children, once they are educated, may refuse to compensate their parents for educational investments. This induces parents to invest too little in their childrens human capital. This effect can be mitigated by unfunded pensions, which give parents a stake in their successors working income.9 In our model, however, individuals underinvest in their own human capital because they neglect the positive side effects of their educational investment, unless they are compensated by a proper pension rule. Second, Sinn (1998) investigates a pension scheme where individual benefits are independent of the human capital investment in one's offspring. He shows that such a system may enhance welfare, but never leads to an efficient allocation. We, instead, derive a pension scheme that restores efficiency by conditioning individual pension benefits on the studying time chosen. And third, Sinn's model is static and is not concerned with the growth implications of social security, as we are. It is not our aim to advocate unfunded social security as such. Rather, we provide a counterexample to the existing literature in order to point to a possibly positive feature of real world pension schemes. The relevance of this feature depends, among other things, on the effect that human capital and its intergenerational transmission has on economic development relative to physical capital. Our paper demonstrates that as long as this is an unresolved issue, general statements regarding the impact of social security on economic efficiency and per capita income growth should be made with caution.