A note on non-uniqueness in rational expectations models

McCallum has proposed a solution procedure for rational expectations models - undetermined coefficients with the minimal set of state variables - which can avoid the non-uniqueness problem. This procedure often requires some additional restrictions on the admissible values of the structural parameters. In this note we show that in some cases, these parameter restrictions may be defended with less ambiguity by considering the dynamics of the model, rather than examining particular parameter values, as suggested by McCallum.