Department of Economics, UCSC

This pap er develops a theory of revealed preferences over oneís own and othersímonetary payo§s. We intro duce ìmore altruistic thanî(MAT), a partial ordering over preferences, and interpret it with known parametric mo dels. We also intro duce and illustrate ìmore generous thanî (MGT), a partial ordering over opp ortunity sets. Several recent discussions of altruism fo cus on two player extensive form games of complete information in which the Örst mover (FM) cho oses a more or less generous opp ortunity set for the second mover (SM). Here recipro city can b e formalized as the assertion that an MGT choice by the FM will elicit MAT preferences in the SM and, fur- thermore, that the e§ect on preferences is stronger for acts of commision than acts of ommision by FM. We state and prove prop ositions on the observable consequences of these assertions. Then we test those prop ositions using exist- ing data from investment games with dictator controls and Stackelb erg games and new data from Stackelb erg mini-games. The test results provide supp ort for the theory of revealed altruism.