Migrating propositions and the evolution of Generative Grammar

This chapter considers the way in which linguistic theories develop (or ‘evolve’). Taking the ‘Research Program’ model of scientific theory development as a starting point, the discussion focuses on the intricate relationship between Generative Grammar and Relational Grammar during the period 1965–1988. In particular, the emergence of both the Unaccusative Hypothesis and the Universal Alignment Hypothesis in the Relational Grammar framework is discussed at length, and the subsequent incorporation of both these hypotheses into mainstream Generative Grammar during the early 1980s is closely scrutinised. This case study raises diffi cult questions about the circumstances in which particular linguistic propositions are able to migrate between distinct Research Programs. Explorations such as this inevitably rely greatly on the careful analysis of specific historical examples of theory construction. Consequently, this chapter argues that historiographical investigations must necessarily form an essential part of any general and theoretical assessments of the mechanisms of linguistic theory development.