Limbaugh pioneered positioning himself as truth against mainstream media.

Evidence

Talk radio had already been on the air for thirty years before Rush Limbaugh came along, but, as Tom Nichols explains in his book The Death of Expertise, Limbaugh did something new: “[he set] himself up as a source of truth in opposition to the rest of American media.” Feeling that the rest of the media was “in the tank” for liberals like Bill Clinton, Limbaugh sought to give voice to the rest of America. And he was wildly successful. — Lee McIntyre, Post-Truth, 135

Categorization

• DEFINE: Distinguishes Limbaugh’s innovation: claiming exclusive truth against all other media, versus merely offering partisan commentary.