Considering the Fourth, Considering Time

A friend of mine recently posed the question on Facebook, “WHY IS A FOURTH CONSIDERED DISSONANT IN TWO-VOICE COUNTERPOINT. THAT’S INSANE.”

The answer depends on the time period and the 4th’s function. Medieval music uses fourths, fifths, and octaves in parallel motion. Stable fourths abound in the music of Thomas Adès. In species counterpoint à la Johann Fux, a perfect fourth is considered dissonant in a two voiced texture. The top voice resolves down to a third above the lower voice. In certain musics, the fourth could suggest a second inversion chord. However, planing a series of second inversion chords would destroy its function as a dissonant sonority. There are other musics where a fourth is just a fifth’s inversion and nothing more.

Function determines the consonance or dissonance of any musical event: understand the function and you understand its purpose within the music. What is “insane,” or at least highly unrealistic, is to assume that the function of any musical parameter in a certain music could apply to all other musics.

The fourth is a nifty tool in a composer’s arsenal. Sometimes my fourths are sometimes dissonant and other times quite stable. They can collapse into smaller intervals (and not necessarily a third because a perfect fourth resolving into a stable major second can be beautiful), yet they can also resolve outward. There are even times when the fourths function not as two separate voices but a single entity/voice. Fourths are useful for thickening a voice or as a drone.

Two summers ago, I worked through Fux’s Gradus ad Parnassum. It was a life-changing experience. Its main lessons were, essentially, in the treatment of dissonance and use rhythmic relationships. The rules, which Fux intended to only be followed loosely, involved resolving dissonances as a means of driving the music forward. As a composer, you have to understand what constitutes dissonance in your music.

Through Fux’s treatise, I realized that, at the time I was reading it, I had no strong understanding about what dissonance meant for my previous works-if it even existed in them at all! Dissonance isn’t merely something intervallic. I often use diatonic clusters that function as points of stability rather than the opposite. Instability can come in many forms. For Steve Reich, for example, repetition itself can be a form of dissonance as the listener waits for a change in the music. Often for me, pitch density is just a mater of achieving the resonance and textures I desire. Gradus opened the door to a new depth of understanding.

Another composer-friend once suggested that species counterpoint is about rhythm. He is right. There’s more to it, though, and it was Zarlino who clarified it for me. Counterpoint is just the relationship of musical ideas to each other in time; it is innately rhythmic, and rhythm only exists because we experience life temporally. This has expanded my concept of counterpoint from localized pitch relationships to include large structural relationships. Form is thus an upper level of counterpoint. It was with this understanding that I composed Conversations w/ Ligeti & Heidegger & Mom in the Background . It is structural counterpoint.


A fourth happens when two voices relate to each other simultaneously at such an interval. Its function as a consonance or dissonance depends on its relationship to all the other moments within the piece. The best way to determine whether it is stable or not is to just listen.


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