It is hard to believe that a phrase as dry as “epistemic closure” could get anyone excited, but the term has sparked a heated argument among conservatives in recent weeks about their movement’s intellectual health.

The phrase is being used as shorthand by some prominent conservatives for a kind of closed-mindedness in the movement, a development they see as debasing modern conservatism’s proud intellectual history. First used in this context by Julian Sanchez of the libertarian Cato Institute, the phrase “epistemic closure” has been ricocheting among conservative publications and blogs as a high-toned abbreviation for ideological intolerance and misinformation.

Conservative media, Mr. Sanchez wrote at juliansanchez.com — referring to outlets like Fox News and National Review and to talk-show stars like Rush Limbaugh, Mark R. Levin and Glenn Beck — have “become worryingly untethered from reality as the impetus to satisfy the demand for red meat overtakes any motivation to report accurately.” (Mr. Sanchez said he probably fished “epistemic closure” out of his subconscious from an undergraduate course in philosophy, where it has a technical meaning in the realm of logic.)

As a result, he complained, many conservatives have developed a distorted sense of priorities and a tendency to engage in fantasy, like the belief that President Obama was not born in the United States or that the health care bill proposed establishing “death panels.”