W.K. Wimsatt and Monroe Beardsley, "The Intentional Fallacy"

Claim: the author's intention is neither available nor desirable as a critical standard.

This article does not appear to me (though I am probably not reading carefully enough) to contain an argument against the intentional fallacy. It suggests a number of ways in which reliance on authorial intention might result in false judgments about a work, but these examples seem to avoid treating the more important question of how or why reliance on authorial intention must result in false judgments. Or, how "internal evidence" of (say) a poem might remove the need for intention - they indicate how something about the "movement" of a passage might be sufficient to get the intended meaning across, but they don't really offer support for this vague claim, or clarify how such meaning might be embodied solely in "movement".

The authors suggest in one of their "axioms" that intention is important to "practical messages", but not poetic ones. "We have no excuse for inquiring what part is intended or meant." Why is poetry different in this regard? Does it have to do with poetry's being "compressed" language? Trimmed of all the fat? What does this view mean for the interpretation of other artistic forms, like the novel, where the language is not apparently identical to that used in poetry?