@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 xt and zt+1. To be considered structural and potentially useful as a guide to actual behavior, this model must specify whether xt is influenced by the expectation at t of zt+1 or, alternatively, that zt+1 is directly influenced (via some inertial mechanism) by xt (i.e., that zt is influenced by xt-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.}, }