@techreport{NBERw15234,
title = "Causality, Structure, and the Uniqueness of Rational Expectations Equilibria",
author = "Bennett T. McCallum",
institution = "National Bureau of Economic Research",
type = "Working Paper",
series = "Working Paper Series",
number = "15234",
year = "2009",
month = "August",
doi = {10.3386/w15234},
URL = "http://www.nber.org/papers/w15234",
abstract = {Consider a rational expectations (RE) model that includes a relationship between variables x_{t} and z_{t+1}. To be considered structural and potentially useful as a guide to actual behavior, this model must specify whether x_{t} is influenced by the expectation at t of z_{t+1} or, alternatively, that z_{t+1} is directly influenced (via some inertial mechanism) by x_{t} (i.e., that z_{t} is influenced by x_{t-1}). These are quite different phenomena. Here it is shown that, for a very broad class of multivariate linear RE models, distinct causal specifications involving both expectational and inertial influences will be uniquely associated with distinct solutions--which will result operationally from different specifications concerning which of the model's variables are predetermined. It follows that for a given structure, and with a natural continuity assumption, there is only one RE solution that is fully consistent with the model's specification. Furthermore, this solution does not involve "sunspot" phenomena.},
}