We characterize two lexicographic-type preference extension rules from a set X to the set ? of all orders on this set. Elements of X are interpreted as basic economic policy decisions, whereas elements of ? are conceived as political programs among which a collectivity has to choose through majority voting. The main axiom is called tournament-consistency, and states that whenever majority pairwise comparisons based on initial preferences on X define an order on X, then this order is also chosen by (...) a majority among all other orders in ?. Tournament-consistency thus allows to predict the outcome of majority voting upon orders from the knowledge of majority preferences on their components. (shrink)

We consider the extension of a (strict) preference over a set to its power set. Elements of the power set are non-resolute outcomes. The final outcome is determined by an “(external) chooser” which is a resolute choice function. The individual whose preference is under consideration confronts a set of resolute choice functions which reflects the possible behaviors of the chooser. Every such set naturally induces an extension axiom (i.e., a rule that determines how an individual with a given preference over (...) alternatives is required to rank certain sets). Our model allows to revisit various extension axioms of the literature. Interestingly, the Gärdenfors (1976) and Kelly (1977) principles are singled-out as the only two extension axioms compatible with the non-resolute outcome interpretation. (shrink)