Ever since the birth of their discipline, music theorists have endeavored not only to find specific concepts, laws, and procedures to explain musical phenomena, but also to connect them with concepts, laws, and procedures in other domains. This process is known as naturalizing music theory. The reasons for undertaking such a task are clear enough; naturalizing music theory allows us to see how our knowledge of music coheres with our knowledge in other domains. We want our theories to be coherent because we know that our understanding of music is shaped by many external factors. Furthermore, as we saw in the Introduction, coherence provides us with a concrete criterion for choosing between theories that are otherwise equivalent on evidential and systemic grounds. If we are confronted with two theories that are equally accurate, equivalent in explanatory scope and predictive power, and equally consistent and parsimonious, then we will prefer the one that is most coherent with related disciplines.

Attempts to ground music theory conceptually have traditionally taken one of two main tacks (see figure 6.1, Naturalizing music theory). Many theorists have tried to connect their explanations of music with the acoustic properties of notes. Up until the seventeenth century, they grounded their work in string divisions, but in the eighteenth, nineteenth, and early twentieth ceturies, they have turned their attention to the nature of the overtone series. More recently, however, an increasing number of theorists have moved away from acoustics and have tried to support their work with appeals to the principles of music psychology. This strategy presumes that our theoretical concepts and analytical methods should reflect the ways in which human beings actually listen to and think about music.

As it happens, Schenker and his followers have set about naturalizing their theory in both ways. Schenker himself picked the acoustic route; throughout his career, from the Harmonielehre to Der freie Satz, he connected the principles of tonality to the physical properties of the overtone series. As he explained, “[T]herefore art manifests the principle of the harmonic series in a special way, one which lets ‘The Chord of Nature’ shine through.”