Rationally choosing beliefs: some open questions

Abstract

Carlos Alchourrón, Peter Gärdenfors and David Makinson published in 1985 a seminal article on belief change in the Journal of Symbolic Logic (Alchourrón et al., 1985). Researchers from various disciplines, from computer science to mathematical economics to philosophical logic, have continued the work first presented in this seminal paper during the last two decades. This paper explores some salient foundational trends that interpret the act of changing view as a decision. We will argue that some of these foundational trends are already present, although only tacitly, in the original article by the AGM trio. Other accounts decidedly depart from the view of contraction and revision presented in this seminal paper. I shall survey various types of theories that progressively depart form the axiomatic treatment defended by AGM. First, I consider theories where rational agents are considered as maximizers as opposed to optimizers (in the sense of (Sen, 1997a)). Second, I consider which feasible set to use in contraction understood as a cognitive decision. This leads to rethink the very notion of what minimal change in contraction is. I shall conclude with some philosophical reflections concerning the sort of epistemological voluntarism that is tacit in seeing change in view as a rational choice.