There is thus a fundamental credibility issue about the willingness of the ECB to be a lender of last resort in the government bond markets. This will continue to make the eurozone a fragile construction. As a result, the possibility of a future euro crisis cannot be excluded.

We develop a behavioral macroeconomic model in which agents use simple but biased rules to forecast future output and inflation. This model generates endogenous waves of optimism and pessimism ("Animal Spiritsʺ) that are generated by the correlation of biased beliefs. We contrast the dynamics...