The ONLY thing you can do -- that will be effective -- is tell the other side of the story.
But, if you attempt to "shut down" the fake news, you risk turning those "news" sites into martyrs, and they will draw even more followers.
And, you have to realize that different people have different opinions and ideas, and some fringe sites may appeal to them.
I disagree.
There is no valuable "other side" to true. Well there, is, and it's called false, which is an error, and should only be tolerated in so much as it indicates something that needs to be corrected. We do teach errors in science as a matter of academic education, but we dont broadcast those errors as truth, it's entirely different.
You don't get to blather on about how you discovered a new medicine that cures people, without violating the law. Claims of curative cannot hit the airwaves without the potential for being shut down. But claims that affect national security that are lies, are tolerated? It's nuts.
The only issue here is that historically for news, we have relied on common sense broadcast, self-regulation. Surely on institution would be crazy enough to spout lies all day? They weren't back in the day, or they weren't popular. But the stake are as high as they get in politics, and if it's not illegal, someone will eventually capitalize on it. Which is why we have major "news" outlets that now spout nonsense, CT crap, lies, 24/7, with no checks whatsoever. Self-regulation? They decide they don't want to. People regulate it? They are marketed too, too strongly, and fall victim to the well designed, psychologically sophisticated propaganda. Enter, a problem.
People loved cigarettes too, they were marketed to, got addicted, and the companies made a fortune, but it was killing people directly and indirectly, to a degree that was deemed unacceptable. We do this all the time in adult-world.
Create clear distinctions between credible, reputable, "science-based" news and commentary.
And the rabble is everything else.
Just like in medicine, just like in physics, just like in psychology (To a degree), etc.
You can get a cable show and talk crazy all you want, free speech is not limited in that regard. You will simply not be able to classify your broadcast in a way that indicates you can't pass muster.
Again, we do this in so many fields, and we do it because NOT doing it, is dangerous. No different.