“The trouble with the internet, Mr. Williams says, is that it rewards extremes. Say you’re driving down the road and see a car crash. Of course you look. Everyone looks. The internet interprets behavior like this to mean everyone is asking for car crashes, so it tries to supply them.” The Twitter co-founder, Evan Williams, reflects on what the social media service has wrought on society and how he is trying to change things with Medium, the publishing site.