Abstract : The theory of harmonic vectors (THV) postulates that of the six possible root progressions in a given tonality those up a fourth, down a third and up a second (+4, -3, +2) are present in significantly greater numbers than the complementary root motions down a fourth, up a third and down a second (-4, +3, -2) (Meeùs 1988, 1989, 2000). This imbalance between both root progression categories is considered to shed light on a specific aspect of the tonal system (Meeùs 2001, 63).
In this article, I seek to provide a better understanding of the status of this imbalance. I argue that it is less the change in frequency of the preferred progressions that is critical for harmonic tonality, than the change in their quality. The progressions +4, -3, +2 arise almost accidentally in pre-tonal polyphony through the constraints of contrapuntal rules. On the contrary, in later repertoires, they become a decisive syntactical feature which actively constrains tonality.
To test this hypothesis, a model that combines voice-leading and harmonic progressions will be considered against a body of madrigal cycles by Verdelot, Arcadelt, Lassus, Rore, Wert and Monteverdi. These cycles, published between c. 1530 and 1638, contain about 50 000 chord progressions. The empirical results in conjunction with the model will allow for a close examination of how and why one particular group of root progressions dominates. They will show the phenomena that reflect the changing status of the prevalent root progressions and the technical aspects which may have fostered it. Finally, they will help to identify the compositional possibilities which result from the evolution outlined.
