What are some benefits and drawbacks of the INFJ's tendency to focus on information that validates their worldview?

What exactly makes agricultural economics different from regular economics, and why does it focus so much on things like farming and fishing?
How can Donald Trump call himself "The Peace President" when he has created nothing but hatred and division in our country? He paints all democrats as evil, and he sends troops into democratic cities. This is not the image of a peaceful man.