Rational Inflationary Bubbles

This paper analyzes the possible inception of rational inflationary bubbles under the assumption that the empirically relevant environment precludes the existence of rational deflationary bubbles. The analysis shows that if a rational inflationary bubble exists, then it must have started on the date of initial issuance of the fiat money. Moreover, the existence of a rational inflationary bubble would imply that, prior to the initial issuance of the fiat money, agents who anticipated its introduction expected a rational inflationary bubble to occur. The analysis also shows that once a rational inflationary bubble bursts it cannot restart. The analysis, however, does not preclude the existence of a rational inflationary bubble that shrinks periodically, but never bursts. The limitations on the inception and existence of rational inflationary bubbles also apply to rational exchange-rate bubbles.