The intentional fallacy is the mistake of treating a poet's stated intention as the final authority on a poem's meaning or value. In close reading, the poem itself matters more than what the writer later says they meant, because a text can suggest meanings beyond its maker's explanation.
Readers and critics use the term to warn against judging a poem only by biography, interviews, or private intention instead of by the words on the page and how they work together.
Example
The poet later said the moon in the poem was meant to symbolize hope, but the critic argued that the repeated images of cold and distance made the moon feel more like loneliness, showing why the poem should be read on its own terms.