All Deceptions are Not Alike : Bayesian Mechanism Design with Social Norm Against Lying

We say that a society has a weak norm against lying if, all other things being equal, agents rather lie in such a way that they do not get caught. We show that if this is the case then all incentive compatible social choice functions are Bayesian implementable, and furthermore, implementation can always be done with a mechanism that has a unique equilibrium. As an important corollary this result suggests that there is nothing wrong in relying on the revelation principle: All social choice functions that can be realized as a truthful equilibrium of a direct mechanism can also be implemented