Last summer Norway suffered a terror attack that struck at the heart of multiculturalism. Today I gave a keynote address at the annual conference of the Contact Committee for Immigrants and the Authorities (KIM) and decided to use that opportunity to discuss ways in which social media can be used to fight back against extremism and intolerance (slides below).  Social media can be used to create both narrow tribes living in echo chambers and inclusive communities that embrace difference.  It’s up to citizens to define the character of social media by challenging and exposing hateful ideologies.