Consonance and Dissonance

Despite their fundamental importance to music theory, consonance and dissonance are surprisingly slippery concepts. They cannot unequivocally be identified as acoustical, aesthetic, physiological, psychological, or cultural-historical. This chapter examines a wide range of approaches to consonance/dissonance, focusing on four debates: the age-old sensus/ratio discussion, contrapuntal treatises, non-Western evidence from cognitive science, and evolutionary arguments. The discussion includes musical examples by Joseph Haydn, Alban Berg, Tsimane′ singing, and various European compositions from the seventeenth to the twentieth centuries. It is impossible to fully close the gap between different approaches, in part because different definitions take their starting points in different objects: cognitive approaches work with sounds while music-theoretical traditions work with notes and intervals. But the diversity of approaches opens up new angles on certain conflations that music theory often tolerates—such as the equivocation between successive and simultaneous intervals—to illustrate how the consonance/dissonance pair functions in different contexts.