We provide an example that shows that in the Alesina and Angeletos (2005) model one can obtain multiplicity even if luck plays no role in the economy. Thus, it is not critical that the noise to signal ratio be increasing in taxes, or that desired taxes are increasing in the noise to signal ratio.

We define the empirical content of an economic theory as the least restrictive observationally equivalent theory. We show that the empirical content of a theory is captured by a certain kind of axiomatization, with axioms that are universal negations of conjunctions of atomic formulae.

Firms and workers may sign complex contracts that govern many aspects of their interactions. I show that when firms regard contracts as substitutes, bargaining over contracts can be understood as bargaining only over wages. Substitutes is the assumption commonly used to guarantee the existence...