The works of John Adams (1947- ) depart from the Minimalist tradition despite the congruity. Minimalism is characterised by restorative features of tonality albeit "functionlessness", one manifestation of which has been the absence of modulation. A technique Adams admits to is the use of modulation in his compositions. Analyses of some of his music seeks to discover the nature and identity of this modulation.
John Adams' departure from the Minimalist tradition is a somewhat similar predicament faced earlier by Franz Schubert. The compositions of Franz Schubert represent a departure from Classical norm yet do not fit comfortably with the Romantic tradition. Analyses of Schubert's sonata-form compositions examine the use of modulation and unorthodox procedures in relation to Classical and Romantic traditions.
The nature of modulation in the works of the two composers is then assessed and posited first, in relation to their respective contemporaneous traditions and second, in a broader perspective. Acceptance of a concept of modulation in both composers is problematic because modulation, as it is understood today, is exclusively associated with theory and practice of major-minor tonality. Its existence as metabole in theory and practice as early as the fifth century BC through to the practice of the twentieth century characterised by a multiplicity of definitions only exacerbates the problem.
Nevertheless, through chronology the common characteristic of modulation has been change articulated by pitch; reliant on a view of tonality that is broad enough to represent music from the fifth century BC to the present. What tonality does refer to, perceptually, is the articulation of a tone or tones expressing a unified central point of reference at various structural levels. Consequently, this broader perception of tonality re-interprets modulation as a change in pitch-centric-focus. A broader concept of modulation not only embraces the system of major-minor tonality but potentially other systems of tonality as well. Acceptance of this broader perspective, however, is eventually perceptual in nature and can be identified by analytical examination but has little by way of concrete theoretical premises. The ultimate challenge remains to work towards a historically and aesthetically satisfactory concept of modulation.