The distinction between poetry and prose has never worried me too much. The only people who need to worry are judges, editors and anthologists - if they get it "wrong" they'll receive lots of feedback and might not be asked to do the job again. Some people try to define poetry based on analysis of the text, often using unquantifiable terms like "density" and "intensity". Sound is frequently mentioned in these definitions. This approach faces several problems
- Such definitions tend to exclude accepted poetic genres - e.g. light verse, shaped poetry, poems like "The Red Wheelbarrow", or LANGUAGE poetry
- The definitions tend to stray into discussing Quality rather than Category issues, describing what a good poem should have rather than what a poem requires
- Borderline texts ("Found poetry", "Prose poetry") are difficult to handle
Reader-centred approaches seem more useful. Rather than classifying texts as "poetry" or "prose", there are "poetic" and "prosaic" ways of reading. Some texts reward a poetic reading more than they do a prosaic reading. Readers have expectations when told that a text is a poem, and their reading strategy is different for poetry than for prose. There'll be variation between readers, and some readers may change their reading strategy according to the poem's sub-genre. Here's a list of some common expectations and assumptions based on P.Begemann's "Reader's Strategies in Comprehending Poetic Discourse"
- the work is textual
- the work is a unified whole, with a title
- the work has a message
- the work is non-utilitarian
- the work has an author
- attention to surface structures
- freedom to associate, speculate and consider emotional implications
- tolerance of difficulty
- readiness to "make sense" of everything
Some of these expectations are shared by viewers of art works in general. None of them is essential.
Some people adopt these strategies readily and in many contexts. More often, something needs to trigger such a response. Most poems are clearly signposted as such (e.g. they're in a poetry book, or they have line-breaks) so readers generally know when a poetic strategy is being suggested.
A found poem is a piece of text whose context is changed so that readers are encouraged to adopt poetic reading strategies. When Yeats added some of Pater's prose to a poetry anthology he needn't have added a title and line-breaks, but doing so reduced the chance of rejection by readers.
I don't think that the above description should be controversial - to me it merely describes how readers behave. Readers of maths texts, detective novels, recipes, etc will also have expectations and strategies. They too will need to contribute to the text, but they'll be faced with fewer borderline cases (in particular, they'll be faced with few works that deliberately challenge the borderlines). Reader-centredness raises some issues for the writer
- What's to stop people reading far more into a poem than is "really there"? - not much. Some poets will encourage readers to get more from a poem than the poet's consciously put in. Others will suppress unintended interpretations. When people discuss their responses to a poem (or when they re-read the poem), there may be some consolidation of views
- How (and how much) should a poet foster poetic reader-strategies? - it will depend on the readership. If it's important that the poem succeeds as a poem, and if the audience doesn't read much poetry, then it's a good idea for the text to fulfil the expectations listed above, and provide rewards for all the listed strategies.
- If a reader claims that a text isn't a poem despite its claims to be so, how can they be convinced otherwise? - one can point out some features that a poetic reader-strategy might reveal, but the disappointed reader may claim that any text will reveal extra features if read with sufficient poetic generosity. The reader still needs to trust the author.
To increase the poetic effect of a text, poets can make the text more "poetic", or they can make the reader adopt a more poetic approach. Context and the author's name are important factors in the reader's choice of strategy, and shouldn't be disregarded by the writer. It's not so much that rhyme and line-breaks (etc) identify a text as a poem, but that making a piece of text look like a poem encourages readers to treat it like a poem.
For poetry to exist, there needs to be a text, a reader, and a suitable "poetic" reading-strategy/setting. In Acumen 54 (Jan 2006) Judy Gahagan wrote "the once unique poetry habitat is a threatened one", a metaphor which can be extended. When a species' habitat shrinks, a few things are likely to happen
- populations become isolated - the performance poets, the academics, the comedians become isolated from each other and develop independently. Some species require large contiguous areas to survive.
- evolutionary pressures change - species survival depends increasingly on its ability to copy with marginal situations and isolation; growth is from the borders rather than the centres
- artificial habitats are created - zoos help species survive, but also lead to cannibalism, inbreeding, loss of parental and eating skills, etc. Poetry magazines can have side-effects too.