Conservative columnist David Frum, who was speechwriter for former President George W. Bush, blasted Fox News on Sunday for creating an "alternative knowledge system."

In an article published by New York Magazine in late November, Frum had argued that conservative media like Fox News and talk radio "immerse their audience in a total environment of pseudo-facts and pretend information."

In an appearance on CNN Sunday, Frum cited claims made on Fox News that President Barack Obama was proposing a "new Christmas tree tax," something that was found by both The Florida Times-Union and PolitiFact Oregon to be not true.

"It fed into a story about this Muslim-y kind of president trying to destroy a Christian holiday," Frum explained to CNN's Howard Kurtz. "To make this a ground for a cultural conflict, to create a sense in large numbers of people they are being persecuted and attacked at a time when the country is in so much trouble, that's how this thing is fed."

"The question is what is the impact on the viewer?" he continued. "And we know, for example, that people that watch a lot of Fox come away knowing a lot less about important world events. That's a correlation that we know."

Recent polling appears to back up Frum's assertion.

Fairleigh Dickinson University found last month that "some outlets, especially Fox News, lead people to be even less informed than those who say they don’t watch any news at all."

"For example, people who watch Fox News, the most popular of the 24-hour cable news networks, are 18-points less likely to know that Egyptians overthrew their government than those who watch no news at all (after controlling for other news sources, partisanship, education and other demographic factors)," they wrote. "Fox News watchers are also 6-points less likely to know that Syrians have not yet overthrown their government than those who watch no news."