economists. Some, like Milton Friedman, have questioned the validity of the rational expectations assumption. Sanford Grossman and Joseph Stiglitz argued that even if agents had the cognitive ability to form rational expectations, they would be unable to profit from the resultant information since their actions would then reveal their information to others. Therefore, agents would not expend the effort or money required to become informed and government policy would remain effective. The New Keynesian economists Stanley Fischer (1977) and Edmund Phelps and John B. Taylor (1977) assumed that workers sign nominal wage contracts that last for more than one period, making wages "sticky". With this assumption the model shows government policy is fully effective since, although workers rationally expect the outcome of a change in policy, they are unable to respond to it as they are locked into expectations formed when they signed their wage contract. Not only is it possible for government policy to be used effectively, but its use is also desirable. The government is able to respond to stochastic shocks in the economy which agents are unable to react to, and so stabilise output and employment. The Barro–Gordon model showed how the ability of government to manipulate output would lead to inflationary bias. The government would be able to cheat agents and force unemployment below its natural level but would not wish to do so. The role of government would therefore be limited to output stabilisation. Since it was possible to incorporate the rational expectations hypothesis into macroeconomic models whilst avoiding the stark conclusions that Sargent and Wallace reached, the policy-ineffectiveness proposition has had less of a lasting impact on macroeconomic reality than first may have been expected. In fact, Sargent himself admitted that macroeconomic policy could have nontrivial effects, even under the rational expectations assumption, in the preface to the 1987 edition of his textbook Dynamic Macroeconomic Theory: 'The first edition appeared at a time when discussions of the 'policy-ineffectiveness proposition' occupied much of the attention of macroeconomists. As work of John B. Taylor has made clear, the methodological and computational implications of the hypothesis of rational expectations for the theory of optimal macroeconomic policy far transcend the question of whether we accept or reject particular models embodying particular neutrality propositions... The current edition contains many more examples of models in which a government faces a nontrivial policy choice than did the earlier edition.' Despite the