Either/or

Does anyone know a good phrase for the action of speaking in terms of alternatives that embody too much contrast? Too much in the way of extremes? A better phrase than "black and white with no shades of grey"?

That kind of speech (and thought) is what I always think of as "polarizing." I don't know whether that would be meaningful to your intended audience, however. Another possibility is "no middle ground."

And then there's "either/or."