My thinking on this continues to change. I always think of Randall Jarrell’s comment that “Poetry is a bad medium for philosophy. Everything in the philosophical poem has to satisfy irreconcilable requirements: for instance, the last demand that we should make of philosophy (that it be interesting) is the first we make of a poem.”
I resist this, of course, because it seems to me that any decent piece of philosophy will tell us something new and significant about the world, and so can’t help but be interesting. But let’s suppose that Jarrell meant something else, that the poet, unlike the philosopher, is allowed and even required to do anything to make a poem work—to make it interesting, to make it a good read. You can include falsehoods, questionable statements, stuff you don’t know, stuff that just sounds good, stuff you just make up. Whatever works. Just as the poet gets to twist and violate the rules of grammar and syntax, to stuff her poem full of non sequiturs and illogical swerves, etc—it’s all part of the same package, the package that gets called ‘poetic license,’ I suppose.
Whereas when doing philosophy, while you may end up saying something interesting, something that gives pleasure or delight, something that is memorable or moving, you aren’t allowed to aim at being interesting, delightful, moving, etc. in the same way; you have to aim at understanding, at achieving an accurate and insightful picture of things, and you are bound by the rules and practices that govern that sort of inquiry. And then, once that is done, being interesting—or giving delight, or moving the reader, or what have you—is something that can happen, but only as, in essence, a kind of side-effect.