After Pope, in the beginning of Romanticism, people developed the idea that imagination rather than reason was a special form of knowledge and its best expression is through poetry. Therefore, poetry should not try to do the stuff that mere prose does: convey information or make arguments about ideas.
Robert HassWhen I began writing poems, it was in the late 60s and early 70s when the literary and cultural atmosphere was very much affected by what was going on in the world, which was, in succession, the civil rights movement, the antiwar movement, and the women's movement in the 60s, 70s, and into the early 80s. And all of those things affected me and affected my thinking, particularly the Vietnam War.
Robert HassPound described poetry as original research in language, and just as formal experiment in poetry has to try things and has to go too far, so does experiment with writing about politics in poetry and what the politics of poetry is.
Robert HassI think that the job of poetry, its political job, is to refresh the idea of justice, which is going dead in us all the time.
Robert Hass