> We form an emotional impression first, then we build a belief around it, and then we go looking for facts that support it. This is my theory as to why we’re so divided in this country.

While this is true, the reason we are much more divided country than in the past is that today's tech actively amplifies this. You can always find the news to support your belief, and social networks are tuned to reinforce it. This is a vicious circle - the more we are divided, the more division is propageted.