Knowledge that Transforms

Journal Article Announcement Get access The Quarterly Journal of Economics, Volume 115, Issue 1, February 2000, Page i, https://doi.org/10.1093/qje/115.1.i Published: 01 February 2000

Announcement The Quarterly Journal of Economics, Volume 115, Issue 4, November 2000, Page iii, https://doi.org/10.1162/003355300554980 Published: 01 November 2000

Economics is not only a social science, it is a genuine science. Like the physical sciences, economics uses a methodology that produces refutable implications and tests these implications using solid statistical techniques. In particular, economics stresses three factors that distinguish it from other social sciences. Economists use the construct of rational individuals who engage in maximizing behavior. Economic models adhere strictly to the importance of equilibrium as part of any theory. Finally, a focus on efficiency leads economists to ask questions that other social sciences ignore. These ingredients have allowed economics to invade intellectual territory that was previously deemed to be outside the discipline's realm.

This paper shows that the phenomenon of multiple equilibria can be fragile to the introduction of aggregate shocks. We examine a standard dynamic model of sectoral choice with external increasing returns. Without shocks, the outcome is indeterminate: there are multiple rational expectations equilibria. We then introduce shocks in the form of a parameter that follows a Brownian motion and affects relative productivity in the two sectors. We assume that the parameter can reach values at which working in either sector becomes a dominant choice. A unique equilibrium emerges; for any path of the random parameter, there is a unique path that the economy must follow. There is no role for multiple, self-fulfilling prophecies or sunspots.

Israeli Ultra-Orthodox men study full-time in yeshiva until age 40 on average. Why do fathers with families in poverty choose yeshiva over work? Draft deferments subsidize yeshiva attendance, yet attendance typically continues long after exemption. Fertility rates are high (TFR = 7.6) and rising. A social interaction approach explains these anomalies. Yeshiva attendance signals commitment to the community, which provides mutual insurance to members. Prohibitions strengthen communities by effectively taxing real wages, inducing high fertility. Historically, the incursion of markets into traditional communities produces Ultra-Orthodoxy. Subsidies induce dramatic reductions in labor supply and unparalleled increases in fertility, illustrating extreme responses social groups may have to interventions.

Monetary rules matter for the equilibrium rate of employment when the number of price-wage setters is small, even when assuming rational expectations, complete information, central bank precommitment, and absence of nominal rigidities. If the central bank is nonaccommodating, sufficiently large unions, bargaining independently, have an incentive to moderate sectoral money wages, and thereby expected real wages. The result is an increase in the real money supply, and hence higher demand and employment. This does not hold with accommodating monetary policy since unions' wage decisions cannot then affect the real money supply. A similar argument holds for large monopolistically competitive price setters.

The major contributions of twentieth century econometrics to knowledge were the definition of causal parameters within well-defined economic models in which agents are constrained by resources and markets and causes are interrelated, the analysis of what is required to recover causal parameters from data (the identification problem), and clarification of the role of causal parameters in policy evaluation and in forecasting the effects of policies never previously experienced. This paper summarizes the development ofthese ideas by the Cowles Commission, the response to their work by structural econometricians and VAR econometricians, and the response to structural and VAR econometrics by calibrators, advocates of natural and social experiments, and by nonparametric econometricians and statisticians.

We study elections in which one party (the strong party) controls a source of political unrest; e.g., this party could instigate riots if it lost the election. We show that the strong party is more likely to win the election when there is less information about its ability to cause unrest. This is because when the weak party is better informed, it can more reliably prevent political unrest by implementing a “centrist” policy. When there is uncertainty over the credibility of the threat, “posturing” by the strong party leads to platform divergence.