In a 1985 paper, [Jean Tirole] offered three conditions needed to create a bubble: durability, scarcity and common beliefs. ‘The possibility of creating too much’ of an asset ‘may prevent bubbles,’ he wrote. ‘The scarcity requirement explains why, at first sight, bubbles often affect assets that for historical reasons cannot be reproduced.’

– Nick Timiraos and Charles Duxbury, in the Wall Street Journal article “5 Contributions to Economics from Nobel Winner Jean Tirole