 Language is extremely flexible.And there is nothing in economic theory that pins down how we discuss economic theory.Kotlikoff and Green claim that fiscal variables in all mathematical economic models involving rational agents can be labeled freely and tell us nothing about the models themselves (no more than does choosing to discuss the models in French or English), and this means that the multitudinous econometric studies relating well-defined economic variables, such as interest rates or aggregate personal consumption, to "the" deficit are, economically speaking, content free.