Short Answer
Overview
A plagal cadence is a type of harmonic resolution that moves from the subdominant chord (IV) to the tonic chord (I) in a given key. In Roman‑numeral analysis it is notated as IV–I, and in major keys the chords are typically major triads; in minor keys the subdominant is often a minor or major chord depending on mode and harmonic context. The cadence is characterized by a relatively gentle sense of closure, lacking the strong pull of the dominant (V) that defines an authentic cadence.
The term “plagal” derives from the Greek word *plagios*, meaning “oblique” or “sideways,” reflecting the movement away from the dominant axis. Because of its softer resolution, the plagal cadence is frequently employed at the end of liturgical music, hymns, and folk tunes, where it is sometimes called the “Amen cadence” due to its common use on the word “amen.”
History / Origin
The concept of the plagal cadence can be traced to medieval church modes, where the movement from the reciting tone (often the fourth degree) to the final (tonic) provided a sense of closure. The modern terminology emerged in the 18th century, notably in the writings of Jean‑Philippe Rameau, who described the IV–I motion as a “plagale” cadence. Throughout the Common Practice Period (c. 1650–1900) the plagal cadence became a standard device in both sacred and secular compositions, appearing in works by composers such as J.S. Bach, Mozart, and later in Romantic hymnody.
How It’s Used
Plagal cadences appear across a wide range of genres and ensembles. In choral and congregational settings they often conclude verses of hymns, especially in the final “Amen.” In popular music, the cadence can be heard in folk ballads, gospel songs, and rock ballads that aim for an uplifting, resolved feeling without the dramatic tension of a V–I motion. Notationally, the cadence is shown simply as IV → I, though composers may enrich it with added sevenths, suspensions, or melodic embellishments.
Why It Matters
For musicians, recognizing a plagal cadence helps in analyzing phrase structure, understanding harmonic function, and shaping performance practice. Listeners often perceive the plagic cadence as soothing or affirming, which explains its frequent use at the end of sacred texts and in concluding sections of popular songs. Well‑known examples include the final “Amen” in Handel’s *Messiah*, the closing of the hymn “Amazing Grace,” and the ending of the Beatles’ “Let It Be,” where the IV–I progression provides a comforting resolution.
Common Misconceptions
A plagal cadence is the same as any IV–I movement.
While the basic chord motion is IV–I, the term specifically refers to its function as a cadence, often with voice‑leading that emphasizes the resolution of the fourth scale degree to the tonic.
The plagal cadence is always weaker than an authentic cadence.
Although it lacks the dominant’s strong tension, a plagal cadence can be made equally strong through harmonic extensions (e.g., IV⁷–I) or orchestral coloration.
FAQ
How does a plagal cadence differ from an authentic cadence?
A plagal cadence moves from IV to I, offering a softer resolution, whereas an authentic cadence moves from V to I and creates a stronger sense of finality due to the dominant's tension.
Can a plagal cadence be used in minor keys?
Yes. In minor keys the subdominant can be either a minor (iv) or a major (IV) chord, and the cadence may resolve to i or I depending on the mode and harmonic context.
Is the plagal cadence always considered weak?
Not necessarily. While traditionally viewed as less forceful than an authentic cadence, composers can strengthen it with added sevenths, suspensions, or orchestration, making it equally impactful.
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