Olivier Blanchard

"I refuse to start from the assumption that the role of monetary policy is to control and stabilize inflation. The only acceptable way to start is, I believe, to think of the goal of monetary policy, together with fiscal policy,as the maximization of welfare."

"Crises feed uncertainty. And uncertainty affects behaviour, which feeds the crisis."

"Using the popular macroeconomic models of the time, Lucas and Sargent showed how replacing traditional assumptions about expectations formation by the assumption of rational expectations could fundamentally alter the results.... Most macroeconomists today use rational expectations as a working assumption in their models and analyses of policy. This is not because they believe that people always have rational expectations. Surely there are times when people, firms, or financial market participants lose sight of reality and become too optimistic or too pessimistic... But these are more the exception than the rule, and it is not clear that economists can say much about those times anyway. When thinking about the likely effects of a particular economic policy, the best assumption to make seems to be that financial markets, people, and firms will do the best they can to work out the implications of that policy. Designing a policy on the assumption that people will make systematic mistakes in responding to it is unwise."

"Lucas and Sargent’s main argument was that Keynesian economics had ignored the full implications of the effect of expectations on behavior. The way to proceed, they argued, was to assume that people formed expectations as rationally as they could, based on the information they had. Thinking of people as having rational expectations had three major implications, all highly damaging to Keynesian macroeconomics. ... The first implication was that existing macroeconomic models could not be used to help design policy. … The second implication was that when rational expectations were introduced in Keynesian models, these models actually delivered very un-Keynesian conclusions. … The third implication was that if people and firms had rational expectations, it was wrong to think of policy as the control of a complicated but passive system. Rather, the right way was to think of policy as a game between policy makers and the economy. … To summarize: When rational expectations were introduced, Keynesian models could not be used to determine policy; Keynesian models could not explain long-lasting deviations of output from the natural level of output; the theory of policy had to be redesigned, using the tools of game theory."