Questions: Choosing Chord Inversions for Harmonic Function

Question 1

A student composes a phrase ending on a tonic chord in second inversion, expecting a strong, stable arrival. The passage sounds weak and unresolved. What is the source of this problem?

• A. Tonic chords should never appear at phrase endings
• B. Second inversion is the most stable inversion and should work for arrivals — the problem must lie elsewhere
• C. Second inversion places the fifth of the chord in the bass, creating an unstable, suspended quality that calls for resolution rather than signaling arrival
• D. The problem is that first inversion also creates instability; only a root-position dominant chord sounds resolved

Answer: (C)

Second inversion is the most unstable inversion because scale degree 5 in the bass sets up dominant function rather than projecting tonic stability. The classic use of second inversion (the cadential I6/4) exploits this instability — I6/4 functions as a pre-dominant preparation, not a stable tonic. Using second inversion to end a phrase mistakes the chord's letter-name (I) for its functional effect. Only root-position tonic provides the full harmonic weight of arrival.

Question 2

A composer wants a smooth stepwise descending bass line from scale degree 1 down to scale degree 5. Which principle is guiding her inversion choices?

• A. Root position must always be used to maintain harmonic clarity
• B. Bass-line goals drive inversion choices — each chord is placed in the inversion whose bass note creates the desired stepwise motion
• C. Inversions are chosen based solely on the soprano melody
• D. Harmonic function must always take priority over smooth voice leading

Answer: (B)

Fluent tonal writing often starts from bass-line goals and derives inversion choices from them. A stepwise bass from 1 to 5 might use: I (root position, bass on 1) → I6 (first inversion, bass on 3) → IV (root position, bass on 4) → I6/4 (second inversion, bass on 5). Each inversion is chosen to place the correct scale degree in the bass for the desired bass-line shape. This is the intersection of harmonic function and voice leading working together.

Question 3

A first-inversion tonic chord sounds lighter and more passing than root-position tonic because it has the third, not the root, in the bass.

• T. True
• F. False

Answer: True

The bass note carries significant structural weight in tonal music. When the root is in the bass, the chord projects stability and arrival. When the third is in the bass, the harmony retains its tonal identity (still tonic) but feels less conclusive — it is passing through rather than landing. This is why first-inversion chords are natural in flowing bass lines but would be inappropriate as the final chord of a cadence, which requires root-position tonic for full closure.

Question 4

In a cadential six-four progression (I6/4 – V – I), the I6/4 functions as a stable tonic harmony that prepares the dominant.

• T. True
• F. False

Answer: False

Despite being spelled with tonic pitch classes, the cadential six-four does not function as stable tonic. Scale degree 5 is in the bass — the dominant scale degree — and the chord members above create a suspended effect that implies dominant motion. The I6/4 is more accurately understood as an intensification of the dominant: a pre-dominant chord that makes the subsequent V arrival feel even stronger. Treating it as a stable tonic arrival is one of the most common errors in harmonic analysis.

Question 5

Explain why a second-inversion tonic chord (I6/4) at a cadence does not represent a stable tonic. What is it actually doing harmonically?

Model answer: In the cadential six-four, scale degree 5 is in the bass — the same bass note the following V chord will have. Rather than sounding like a tonic chord in an unstable position, it functions as an elaboration over the dominant bass. The upper voices (forming a 6/4 above the bass) create tension that resolves downward to the fifth and third of the dominant chord when V arrives. The I6/4 belongs to the dominant function, not the tonic function, despite being spelled as a tonic triad.

This is a case where spelling and function diverge — a critical concept in harmonic analysis. The chord is spelled with tonic pitch classes but functions as part of the dominant. Recognizing this requires understanding that harmonic function is determined by context and bass position, not just by which pitch classes are present. The cadential I6/4 is one of the clearest demonstrations that inversion choice is functionally consequential, not merely coloristic.