This thesis investigates the transformation of Joseph Priestley’s Rudiments of English Grammar between 1761 and 1769. The later editions of Priestley’s grammar have long attracted the interest of historians of linguistic thought for their innovative features, in particular the large appendix of ‘Notes and Observations’ on usage. However, the introduction of these changes has generally been accounted for by presenting Priestley’s work as either a reaction to the success of Robert Lowth’s Short Introduction to English Grammar (1762), or a ‘descriptive’ counterpart to the perceived ‘prescriptivism’ of Lowth’s approach to grammar. The central aim of this thesis is to challenge these narratives by providing new insights into the evolution of Priestley’s thinking and practice as a grammar writer. I identify key factors shaping this evolution which have received little or no attention: the notions of genius and idiom of the language, attitudes towards language contact, pedagogical concerns, the legacy of Samuel Johnson’s lexicography, and the influence of Lewis Chambaud (d. 1776) and Abbé Girard (1677–1748). I argue that the defining features of Priestley’s work are connected to the French language and the French grammatical tradition.

The only previous full-length study of Priestley’s grammar (Straaijer 2011) focused on the socio-historical context of its publication and the descriptive adequacy of his grammatical analysis. By contrast, the present study examines Priestley’s work as a grammaticographic project, the attempt to design a grammar best suited to the language on which it focuses. In the first chapter, I use the methodology of attribution studies to establish that Priestley is the author of a 1765 grammar hitherto attributed to John Baskerville (1707–1775). This major finding leads me, in Chapter 2, to challenge previous accounts of the evolution of Priestley’s thinking on grammar. I argue that Priestley’s project is better understood by taking him out of the shadow of Lowth and focusing on his own view of his achievements. Chapters 3 and 4 therefore consider Priestley’s introduction of the notions of genius and idiom of the language after 1761, and show how they affected the design of his grammatical works. Finally, Chapter 5 traces these changes back to Priestley’s appointment as Tutor in Languages and Belles Lettres at the Warrington Academy in 1761, where he developed concerns about the effectiveness of grammar teaching and became familiar with influential French grammarians and language masters.