This paper presents a model of optimal taxation in which both private agents and the government can default on their debt. We first consider Ramsey equilibria in which the government can precommit to its policies but in which private agents can default. We then consider sustainable equilibria in...

"Financial crises are widely argued to be due to herd behavior. Yet recently developed models of herd behavior have been subjected to two critiques which seem to make them inapplicable to financial crises. Herds disappear from these models if two of their unappealing assumptions are modified: if...