CFDP 1697R

Rationalizable Implementation


Publication Date: May 2009

Revision Date: January 2010

Pages: 29


We consider the implementation of social choice functions under complete information in rationalizable strategies. A strict (and thus stronger) version of the monotonicity condition introduced by Maskin (1999) is necessary under the solution concept of rationalizability. Assuming the social choice function is responsive (i.e., it never selects the same outcome in two distinct states), we show that it is also sufficient under a mild “no worst alternative” condition. In particular, no economic condition is required. We also discuss how our results extend when the social choice function is not responsive.


Implementation, Complete information, Rationalizability, Maskin monotonicity

JEL Classification Codes: C79, D82

See CFP: 1328