Although the term “opinion-based” is hard to find in the Help Center, it seems to be widely considered an undesirable quality for a question or answer. The problem is, what is not opinion-based? Plato insisted on an absolute disjunct between knowledge and opinion (even or especially correct opinion), but in so doing he set the bar for knowledge so high that he himself invariably failed to clear it. Rhetoricians, from his own contemporary and rival Isocrates down to Wayne Booth, have called the distinction sharply in question. In Modern Dogma and the Rhetoric of Assent, Booth uses as an example the proposition that the opening sentence of Pride and Prejudice is ironical (“It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife”). That proposition cannot be scientifically proven; and yet for the MLA to come out against it as a body would, he says, be more startling than for a comparable body of the world’s physicists to declare the hitherto accepted laws of physics overthrown. In his Philosophy of Rhetoric, George Campbell shows that even the composition or perusal of an algebraic proof requires faith in one’s own memory, and notes that the composer is likely to ask a fellow algebraist for an opinion before publishing.
In my own profession of teaching composition, specifically argument, I often encounter the notion, among novice teachers under my supervision, that for an academic argument paper to be “opinion-based” is a Bad Thing. I have found that position puzzling too.
Has the community really considered the epistemological underpinnings of this apparent consensus?