A Note on a Weak Dictator and the Veto Condition

In this note we discuss the relationships between the weak dictatorship axiom, as introduced by A. Mas-Colel and H. Sonnenschein, and the vetoer axiom, as given by P. C. Fishburn, in a wider context of traditional Social Choice Theory (SCT). Namely, we prove the equivalence between these two axioms. This note can be a good formal reasoning exercise for students in the field of preference logic. This note is written as an outline for the 'second' lesson in SCT for non-mathematicians, which contains elementary formal logical argumentation, after the basics of preference logic, and before the extensive and complicated treatment of impossibility theorems.