Toward a Relativity Theory of Rationality

We analyze two conceptions of rationality featured in the social science literature, rationality as a means-ends relation and rationality as logical consistency. The former concerns the rationality of actions; it involves choosing the best means to one's ends and is naturally akin to conceptions of utility. The latter concerns the rationality of judgments, it involves their consistency with other knowledge and is naturally akin to conceptions of truth and probability. We assume that (1) a uniform process of judgment formation is involved in both rational and irrational judgments; it follows that the distinction between more or less rational instances must refer to judgmental outcomes rather than processes; (2) in the moment all judgments are consistent with the available evidence hence all are locally (and trivially!) rational. Accordingly, we present a relativity theory of rationality whereby any meaningful conception of rationality needs to transcend the local context and involve comparisons of local outcomes with detached (inter or intrapersonal) points of reference.