Harmonic dualism

What it means

Harmonic dualism is a music-theoretical concept that treats major and minor as mirror-related modes. The major triad is then seen as a construction upward, derived from the overtone series, the minor triad by contrast as a construction downward, from an imagined undertone series. The two are set against each other like image and mirror image.

Musical use

The concept was developed in the 19th century by theorists such as Arthur von Oettingen and became known above all through Hugo Riemann, who used it in his functional theory. According to it, the minor sonority has the function of an “inverted” major sonority, with the root at the top rather than the bottom. Riemann derived the functional designations from this. The derivation from an undertone series is not physically tenable, since undertones do not occur as natural vibrations, and was therefore later abandoned.

Harmonic dualism should be distinguished from scale-degree theory, which orders chords by the scale alone, and from the approach of deriving minor from the overtone series. It is today rather of historical interest but has shaped the concepts of functional theory.

Performance practice

If you work with functional theory, note that its designations for minor rest on this dualism. More important in practice is the sound image: test how major and minor chords work as reflections by building the same root or the same fifth in both directions.