We analyze the rationalizability of variable-population social-choice functions in a welfarist framework. It is shown that fixed-population rationalizability and a weakening of congruence together are necessary and sufficient for rational choice, given a plausible dominance property that...

This note extends Gorman's [1959] classic result on two-stage budgeting to encompass the two-group cases that he assumed away. The proof, which exploits unpublished and recently published results not available to Gorman in 1959, makes it apparent that the entire structure needed for two-stage...