The introduction of the idea of mode and modality in jazz practice and theory around the end of the 1950s comes a short time before the generalization of chord-scale theory. The latter systematized a tendency to verticality initiated by bebop, in the sense of a more and more sophisticated account of each chord, isolated out of their harmonic suite, to the detriment of the horizontality of an approach privileging the melodic process actually relegating chords in the background. The paradox is that the introduction of modality – for example in the mind of one of its main actors, Miles Davis – intended to rehabilitate a horizontality altered by the post-bop multiplication of chords among tune changes (So What vs. Giant Steps), since chord-scale theory has used the notion of mode in a quite opposite way. The operation consisting of the application of a principle such as “to each chord fit one or mode modes” leads to the consequence of a greater atomizing of chords, even when they are regulated by the tonal logic that proceeds from a basic horizontality (directionality toward the final tonic step).
Schenkerian analysis, or preferably the Schenkerian idea upstream from the method itself, can help us to reconsider this question within a different perspective. Actually, concepts of Ursatz and Urlinie can be of great help to formalize horizontalities present either in compositions used by jazz musicians or in their improvisations. They offer an opportunity to consider the notion of counterpoint in jazz, largely ignored compared to purely harmonic arguments. I will illustrate this through examples taken from a few standards and from Brad Mehldau’s Lament for Linus.