Unfortunately, for most of the population, it’s whatever they read/watch. For many conservatives, Fox News is gospel, and for many liberals, CNN is gospel.
Interestingly when Fox and CNN cover the same political event they can both come to opposite conclusions at the same time that present a victory for their side.
It really is like there are multiple realities.
But luckily enough, CNN and Fox are both more irrelevant than ever. There's a reason no young people watch. Young people get news from YouTube, Snapchat and other new media sources from people they trust.
