Questions: The Cadential Six-Four and Its Voice-Leading Requirements

Question 1

At the end of a Classical phrase, a student sees I⁶₄–V–I and analyzes it as: 'The phrase ends with a tonic chord that provides a moment of rest before the dominant.' What is wrong with this analysis?

• A. The I⁶₄ is not actually in second inversion — it should be analyzed as root position
• B. The I⁶₄ does not provide rest; it intensifies dominant function by placing suspended dissonances above the dominant bass, which must resolve before the true V arrives
• C. A cadential pattern must begin with IV, so I⁶₄–V–I is an incorrect progression
• D. Nothing is wrong — I⁶₄ is a tonic chord and correctly provides a moment of stability before V

Answer: (B)

The cadential 6/4 is functionally dominant, not tonic, despite its Roman numeral label. Scale degree 5 is in the bass, and the upper voices (scale degrees 1 and 3) are suspended dissonances above it — they create tension against the dominant bass rather than rest. The 'I' label reflects the notes in the chord but not its harmonic function. Calling it a moment of rest reverses the reality: it is the point of maximum tension in the cadential gesture.

Question 2

In a cadential 6/4 resolving to V, how must the sixth (scale degree 1) and the fourth (scale degree 3) above the bass resolve?

• A. Upward by step to scale degrees 2 and 4
• B. Downward by leap to scale degrees 5 and 1 to reach the tonic
• C. Downward by step to scale degrees 7 and 2, completing the dominant chord in root position
• D. They may be sustained as pedal tones through the final I chord

Answer: (C)

The sixth (scale degree 1) resolves down by step to the seventh of V (scale degree 7), and the fourth (scale degree 3) resolves down by step to the fifth of V (scale degree 2). This is the paradigm of suspension resolution: preparation (as chord tones in the previous harmony), the dissonance point (hovering as 1 and 3 above the dominant bass), and stepwise downward resolution. Upward resolution or leaps would violate the voice-leading logic of the suspension pattern.

Question 3

The cadential 6/4 has scale degree 5 in the bass, making it structurally a dominant prolongation despite the tonic notes appearing in the upper voices.

• T. True
• F. False

Answer: True

The bass note is scale degree 5 throughout the cadential 6/4 — the same bass note as the following V chord. This is why the cadential 6/4 extends dominant function: the bass is already anchored on the dominant, and the upper voices' tonic notes (1 and 3) are dissonances against it, not consonances completing a tonic harmony. When they resolve to 7 and 2 (V's chord tones), the harmony clarifies to a root-position dominant. The entire gesture prolongs scale degree 5 in the bass.

Question 4

The cadential 6/4 can appear freely at any point within a phrase because it functions as a stable tonic sonority that can support melodic activity.

• T. True
• F. False

Answer: False

The cadential 6/4 is cadential — it appears at phrase endings, just before V–I, as an intensification of the dominant. It requires specific voice-leading conditions: scale degree 5 in the bass, both the sixth and fourth prepared from the preceding chord, and stepwise downward resolution. Using it mid-phrase without resolution to V violates its functional identity. Its power comes from its specific placement in the phrase as the moment of maximum tension before the authentic cadence.

Question 5

Why is the Roman numeral label 'I⁶₄' considered functionally misleading for the cadential six-four? What is the chord actually doing harmonically?

Model answer: The label 'I⁶₄' correctly identifies the pitch content (scale degrees 1, 3, and 5, with 5 in the bass) but misrepresents the harmonic function. The chord functions as a dominant prolongation: scale degree 5 is in the bass, and the upper voices (scale degrees 1 and 3) are suspended dissonances that create tension against the dominant bass. They behave like appoggiaturas — arriving from the previous harmony, sitting as unstable notes above the dominant, and resolving stepwise down to V's chord tones. The 'tonic' notes are not providing tonal stability; they are generating harmonic tension that demands resolution.

This is one of the clearest examples in tonal theory of the gap between a chord's label and its function. Roman numeral analysis identifies what notes are present; harmonic function analysis describes what role those notes play in the phrase. The cadential 6/4 is categorically dominant in function even though it borrows tonic-triad notes for its upper voices.