Unification: not just a thing of beauty

Abstract

We often hear that simplicity, explanatory power and unification, though aesthetically pleasing or beautiful qualities, are at best pragmatic considerations in matters of choosing between rival hypotheses. This paper aims to offer a novel conception and an associated measure of unification, both of which are demonstrably more than just pragmatic considerations. The discussion departs from a brief survey of some failed attempts to carve out adequate conceptions of unification. It then proceeds to an analysis of the notions of confirmational connectedness and disconnectedness. Roughly speaking, these notions attempt to capture the way support propagates or fails to propagate between the content parts of a hypothesis or, equivalently, between the contents of two or more hypotheses. The two notions are instrumental in helping to tackle the problem of ad hoc, and in particular monstrous, hypotheses. More importantly for the purposes of this paper, they are essential ingredients in the proposed conception of unification and its associated measure. In simple terms, the more the content of a hypothesis (or, equivalently, the content of a set of hypotheses) is confirmationally connected the more that content is unified. Since the confirmational connectedness of two content parts is determined by purely objective matters of fact, the proposed notion and measure of unification are themselves strictly objective, i.e. not merely pragmatic considerations in matters of hypothesis choice. The paper concludes with a discussion of how the proposed measure handles real and hypothetical examples but also how it stands up to various objections.