Treading a fine line: (im)possibilities for Nash implementation with partially-honest individuals

This paper investigates the robustness of Dutta and Sen's (2012) Theorem 1 to weaker notions of truth-telling. It models individual i's honesty standard as a profile of (possibly non-empty) collections of ordered pairs of outcomes, one for each member of society, over which individual i feels truth-telling concerns. Individual i is honest provided that she states her true preferences as well as rankings (not necessarily complete) of outcomes that are consistent with the true preferences of individuals in her honesty standard. Under this notion of honesty, we offer a condition, called -partial-honesty monotonicity, which is necessary for Nash implementation when there are partially-honest agents. In an independent domain of preferences, we show that this condition is equivalent to Maskin monotonicity provided that honesty means stating the orderings of individuals (in a honesty standard) truthfully and individuals' honesty standards are non-connected.