Plagal Harmony as Other: Asymmetrical Dualism and Instrumental Music by Brahms

Abstract

The late 19th-century dualism of Hugo Riemann exemplifies a widely recognized tendency in Western cultures to think in binary pairs. In recent theoretical writing the primary dualism between major and minor modes has provoked little or no controversy. But the attendant opposition between, respectively, authentic and plagal harmonic systems has not found widespread acceptance, because theorists have been unwilling to grant the latter equal status to the former. An alternative is to accept the validity of the two systems and at the same time to recognize the inequality that comes with any binary pair, thus acknowledging the "otherness" or, to borrow a term from linguistics, the "markedness" of the plagal system. In an essay from 1889, Riemann explored striking harmonic effects in the Andante of the Fourth Symphony and another late orchestral movement by Brahms, discerning the same non-diatonic scale behind the (plagal) idioms in both. The Phrygian and Aeolian scales enable similar unusual plagal passages in two chamber movements by Brahms, the early Adagio mesto of the Horn Trio and the very late opening Allegro from the Clarinet Trio. In these movements plagal harmony appears in a strong sense as the other of authentic harmony and perhaps even of common-practice tonality itself. The semantic significance of certain plagal moments in both has to do above all with their ability to suggest something other than, outside of, or prior to tonal music.