BLAINVILLE'S NEW MODE, OR HOW THE PLAGAL CADENCE CAME TO BE ‘PLAGAL’

Abstract

ABSTRACTThe plagal cadence has long been a significant concept within musical discourse, but that discourse contains no convincing explanation of why the progression should be characterized as ‘plagal’. This article elucidates the meaning of the term ‘plagal cadence’ by examining its introduction into a mid-eighteenth-century Parisian debate over the nature of what would come to be called tonality instigated by Charles-Henri de Blainville's proposal of the ‘mixed mode’, a supplement to the major and minor modes. Owing to the properties of his new mode's scale, which corresponds to the Phrygian mode, Blainville identified the plagal cadence as the proper conclusion for pieces in the mixed mode. Curiously, although Blainville's work appears to contain the first published articulation of the term, he employs it as if his readers were already familiar with the ‘plagal cadence’. This article explains that oddity, finding that Blainville misread earlier accounts of plainchant as saying that plagal modes were characterized by the interval of the descending fourth. In conclusion, consideration of the controversy regarding the mixed mode and plagal cadence reveals that those historical disagreements bear striking similarities to current debates over the significance and function of the plagal cadence in theories of harmony.