Kevin Drum offers a theory that the internet drives increases of cognitive inequality. Put simply, "the internet makes dumb people dumber and smart people smarter." (the post was from 2012, but I came across it today). Basically, his point is that the internet makes available a massive glut of information -- accurate and inaccurate -- to the everyday population. If you know how to put in proper searches and have decent source-appraisal and critical-reasoning skills, you can become much, much smarter. If you lack these attributes, by contrast, you'll be a lot dumber.
This theory makes some sense to me, but I'm also interested in how it lines up with some of the motivated cognition research I've become increasingly interested in. An important part of that research is that we selectively interpret the information we receive -- and the information sources we pursue -- so that they are in harmony with our preexisting beliefs. So liberals avoid or discredit Fox, and conservatives do the same to MSNBC. And the thing is, it is very hard to disentangle that sort of motivated reasoning from critical appraisal. If I scroll over a link, see it's going to Breitbart, and say "pssh, obviously I don't need to read that tripe," am I wisely ignoring an incredible source, or am I avoiding information that might disrupt my carefully crafted belief structure? The answer is almost certainly some of each; but how much of each is difficult to determine. Indeed, how do I know that Breitbart lacks credibility? For the most part, it's because (a) a large quantity of sources within my epistemological network say it is and (b) from experience I know that their statements clash pretty consistently with my ideological priors. How is that different from motivated cognition? And we can run this in reverse, of course (witness the worries about "epistemic closure" on the right, or take it even further afield -- how do I know to dismiss conspiracy theories? I never landed on the moon; ultimately, I'm making a decision that NASA and like sources are more credible than expose-the-hoax.angelfire.com based on surprisingly thin gruel.
Ultimately, as depressing as Drum's hypothesis seems to be, I want to believe it is right because it indicates that education and knowledge can nudge us in the right direction of being better thinkers. But people are notoriously difficult to persuade, even when they're wrong. It is possible that the internet doesn't so much further cognitive inequality as it furthers cognitive divergence -- sending each of us down a personalized rabbit hole of groupthink and confirmation bias wherein every thought we think (right or wrong) can find a network of supporting architecture immunizing it from effective critique.