Paper
The “policy inefficacy” principle is probably one of the most famous and controversial assertions of the New Classical School which is often regarded as a (counter)revolution in macroeconomic theory. We shall see, however, that despite the important insights and innovations of the approach, most of its conclusions including the invariance postulate are based on quite restricted and unrealistic assumptions and assertions which may make them of doubtful practical use. The NC approach is characterised by its “relentless drive for microfoundations” and in particular the desire to base their theories on the assumption of the Rational Economic Man as a reaction perhaps to such Keynesian theories as “animal spirits”, money illusion or the liquidity trap which seemed to imply “irrational” individual behaviour. Economic agents are, thus, seen as consistent and successful optimisers to the limits of their information which implies that agents are continuously in equilibrium. This coupled with the assumption of universal perfect competition ensures that markets always clear, unlike most “classical” – and monetarist – economists who considered equilibrium as a limiting case. NCs therefore work within a Walrasian General Equilibrium unlike Monetarists who often preferred a Marshallian partial equilibrium approach. As required by Walrasian equilibrium the Classical Dichotomy is also re-established and Aggregate Supply (AS) is assumed to depend only on relative prices. As we shall see NCs restated even more strongly than monetarists the neutrality and superneutrality of money. Another important feature of the NC school is its adoption of Rational Expectations (RE) first developed by Muth. RE assume that people engage in a cost-benefit analysis of whether it is worth searching for certain forms of information and then make efficient use of the information available to them by understanding how the economy works and continually revising expectations to take into account of any new information. NC theory focuses in particular in the efficient use of information aspect of RE, having little to say on how this information is obtained. Lucas and Prescot thus defined RE as the situation where the subjective probability distribution of future economic variables held at any time t coincides with the actual, objective conditional distribution based on the information assumed to be available at that time t. NC economists accepted and extended Friedman’s notion of the natural rate of unemployment which refers to the level of unemployment consistent with stable inflation and labour market equilibrium and is, thus, thought to be “voluntary”. For Friedman adaptive expectations meant that though the Long Run Phillips Curve is vertical on the natural unemployment rate – and correspondingly AS is vertical on the level of “permanent” output, the Short Run Phillips Curve and AS are downward and upward sloping respectively. This was so because inflationary expectations were slow to adjust and, therefore, workers and -sometimes- employers suffered from money illusion. Thus Friedman did allow for Demand Management (monetary policy only of course) to affect output in the short run. The introduction of RE, however, meant that any systematic govt policy will not be able to affect output because rational agents will – immediately – adjust their inflationary expectations. Keynesians were, thus, accused of overlooking the fact that structural parameters change with government policy. This inability of a feedback money supply rule to affect output was termed by Sargent and Wallace as the “superneutrality” of money. Temporary divergences from the natural rate could only occur if the authorities – or any real shocks – managed to surprise individual agents. Hence, Lucas “surprise” AS function is derived : Y = Yp + a ( P – Pe ) (1) where Yp is the mean or permanent level of output, Pe is the expected aggregate price level and a is a positive constant . The above equation can also be expressed in logs so as to represent rates of change of output and prices (i.e. inflation). Nevertheless, an explanation is required of why incorrect inflationary expectations alter output. The answer NCs give is imperfect information (this is often explained in terms of the “island parable”). Agents have information of the current price (PX) of the good X they produce but they cannot observe all prices in the economy and hence do not know the current aggregate price level (P). Thus, following a change in PX, agents have to distinguish between a change in the relative price of their good and a change in the aggregate price level, i.e.: they are faced with a problem of “signal extraction”. Typically they will interpret it partly as a relative and partly as an aggregate price movement as shown in (2) : Pe = b + c PX (2) The larger c is, the greater is the proportion of changes in PX attributed to a change in the price level. Thus, the more a country varies its money supply growth to affect output, the greater will be the correlation between P and PX and, thus, c will get larger, making signal extraction more difficult. Another question is how is it possible that mistakes in expected inflation cause that big changes in output and employment. The answer given by Lucas here is a distinction between temporary and permanent changes in the relative price of labour (real wage). Permanent changes cause little changes in employment, perhaps even of unknown sign because leisure is a normal good. Temporary changes in real wages, however, can have much larger effects in employment because of the so-called intertemporal substitution of leisure : Workers prefer to work more when real wages are higher than normal and consume more leisure when wages are low. Any (perceived) change in real wages will again be typically partly thought as temporary and partly as permanent; here agents face a double signal extraction problem. Hence to the extent a monetary shock makes agents think a temporary change in their real wages has taken place, it will have a fairly big effect on employment and we, thus, have a downward sloping (very)Short Run Phillips Curve as shown in figure 1. Imperfect information and intertemporal substitution of leisure has been used by Lucas and others to form monetary explanations of the business cycle while alternative NC real explanations of the cycle are also based on this postulate. The important thing to grasp here is that both the movements along the SR Phillips Curve and the trade cycle are not thought to be indicators of (even temporary) disequilibria but optimising and hence equilibrium responses to the available – imperfect – information. This is why Lucas argued that Keynes distinction between voluntary and involuntary unemployment was a misdirected attempt to distinguish between trend and cyclical unemployment. A problem with this theory is that it can explain only very short run fluctuations in output and employment. Indeed, this model suggests that output should be random walk around this trend i.e. its deviations from trend should be serially uncorrolated since agents will be very quickly able to find out if the aggregate price level changed. Obviously output and employment show significant persistence so Lucas has tried to improve the explanatory power of his AS function with an additional term representing deviations of past output from the mean as shown below : Y = Yp + a ( P – Pe ) + g (Y-1 – YP ) (3) This was justified by assuming that money supply shocks