Of two false theories, One can be, Intuitively, Closer to the truth than the other. The purpose of the article is to propose a rigorous explication of this intuitive notion.

This paper is both a survey and a review of the current state of the debate concerning verisimilitude. As a survey it is intended for the interested outsider who wants both easy access to and some comparison between the respective approaches. As a review it covers the first three books on the topic: those of Oddie. Niiniluoto and Kuipers.

relative to the actual world) of a propositional theory are defined. A theory is ‘closer to the truth’ the logically stronger its positive content and the logically weaker its negative content. This proposal delivers the same verisimilar preordering of theories that has been defined by Brink and Heidema as a ‘power ordering’. The preordering may be collapsed to a partial ordering and then embedded into a complete distributive lattice. The preordering may also be refined to a partial ordering by employing (...) the ‘convex content’ and the ‘non-convex content’ of each theory. Philosophical implications and historical relations are discussed. (shrink)

The Egli-Milner power-ordering is used to define verisimilitude orderings on theories from preference orderings on models. The effects of the definitions on constraints such as stopperedness and soundness are explored. Orderings on theories are seen to contain more information than orderings on models. Belief revision is defined in terms of both types of orderings, and conditions are given which make the two notions coincide.