ABSTRACT
If a simple majority voting is taken on each pair of alternatives, a social decision as the juxtaposition of those pairwise comparisons is not always transitive. As we mentioned before, this phenomenon is called voting paradox. Knowledge of voting paradox is centuries old; we can trace it back to Condorcet, an eighteenth-century French encyclopaedist. Quite recently, K. J. Arrow made a remarkable contribution to the subject, proving that the same phenomenon can be observed in a more general class of social decision function, though like many economists Arrow preferred the term social welfare function to our term social decision function. This chapter is devoted to an introduction of his work.
