Ambiguity as Load-Bearing Structure
One line in a poem I published in 2008 was read by a government reviewer as a prayer and by my closest friend, three weeks later, as its precise inversion, an accusation against the thing the prayer was addressed to. Both readings were correct. I had built the line so that both could be.
Ambiguity in most craft discussion is treated as a temporary condition, something a poem has until a close enough reading resolves it into one true meaning, with the resolved meaning counted as the poem's actual content and the ambiguity as scaffolding you remove once the building stands. I do not think this describes what a genuinely ambiguous line does, and I do not think resolution is always the goal. Some lines are built to hold two mutually exclusive readings permanently, neither one collapsing into the other, and the line's whole function depends on both remaining live at once.
The double reading
Call this a double reading: a line engineered so that two contradictory interpretations are both fully supported by the grammar, both survive a close reading intact, and neither one requires the reader to ignore evidence that favours the other. This is different from vagueness, where a reader cannot tell what is meant, and different from irony, where one meaning is clearly intended and the other is clearly a foil. In a double reading, a reader who commits fully to either interpretation will find the line supports that commitment completely, right up until they meet someone who committed to the other one and realise the line supported that just as completely.
My 2008 line, addressed to a beloved that could be read as a lover or as the country itself, read: you kept me only long enough to teach me what keeping means. A reader hearing this as a prayer to a lover reads keeping as devotion, however painful, a lesson learned inside love. A reader hearing it as an address to the state reads keeping as detention, the specific keeping of a body the state controls, and the lesson as what confinement teaches about possession. Both readings use every word in the line without alteration. Neither reading requires suppressing the other's evidence. The line does not choose between them, and I did not choose either while writing it, which is the actual craft claim: I was not being clever about hiding one true meaning inside a decoy. I was building a structure that could bear two full, incompatible loads at once without either one buckling.
Why this requires more than clever wording
A double reading fails, and becomes mere vagueness, the moment one reading requires the line to work harder than the other, because a reader always finds the reading that costs less effort and treats the other as decorative. To build a genuine double reading, I test each candidate reading independently, reading the poem as if the other interpretation did not exist, checking whether every image still functions on its own terms. Keeping, in my line, had to independently support both devotion and detention without either one feeling like a stretch, and the only way to verify that is to read the poem twice, fully committed each time to the reading being false, and see if anything creaks.
The obvious counter
The case against this technique, made to me directly by an editor I respect, is that a poem holding two readings equally is a poem that has failed to decide what it is about, and that a writer who cannot commit to one meaning is asking the reader to do the deciding the writer should have done first. I take this seriously because it is often the correct diagnosis of a genuinely confused poem. My answer is narrow: the test is whether the writer can articulate both readings precisely, in full, on demand. A confused poem produces one clear reading and one mush. A double reading produces two clear readings that happen to contradict each other, and a writer who can state both exactly has not failed to decide, they have decided that the subject itself, a beloved that is also a country, a keeping that is also a captivity, cannot be honestly reduced to one without falsifying the other.
My friend and the reviewer never learned they had read the same line into opposite meanings. I have never told either of them, because the poem's actual achievement was making that possible, silently, in the same eleven words, and explaining it would have been the one thing capable of collapsing it.