Over time, in jazz what we may call a ‘canon’ of harmonic know-how began to emerge. The first and foremost purpose of this know-how was to provide players with a musical vocabulary. The focus lay in particular on those elements that were seen as specific to jazz, as compared to traditional Western harmony. Seen from a distance, there seems to be a fair amount of consensus on the basic concepts of jazz harmony, especially as one finds them in jazz pedagogical materials. But on closer investigation, central notions like ‘diatonicism’, ‘mode’ and ‘modality’, and even ‘tonality’ are hazy, and not always understood in the same way.
Among the most important but at the same time most problematic notions are those of ‘mode’ and ‘modality’. Although appropriated from Western art music, these terms took on other meanings in the context of jazz. This paper investigates the different ways in which these concepts function in jazz practice, focusing on pedagogical materials, and explores and evaluates the different, often implicit, definitions, and their performative implications for the music. It traces possible historical sources, both in the music itself (discussing examples of music by Gil Evans, Miles Davis, Lennie Tristano) and in theoretical writings (George Russell, Joseph Schillinger). Given the embeddedness of these terms in jazz harmony, rather than proposing radical new terminology, the aim of the paper is to bring some conceptual and theoretical clarity, in the hope that this will be of benefit for our analytical understanding of jazz and for jazz theory pedagogy.