FiveThirtyEight founder and Editor in Chief Nate Silver talks with Peter Kafka about the 2016 election, and why his site was one of many that didn't see Donald Trump coming. He calls Trump a "demagogue" who has succeeded under extraordinary circumstances and says he has a 25 percent to 30 percent chance of winning the general election if he becomes the Republican nominee. Plus: The end of Grantland and why Silver loves the Golden State Warriors.