The fact that so many people choose to live in ways that narrow the community of fate to a very limited set of others and to define the rest as threatening to their way of life and values is deeply worrying because this contemporary form of tribalism, and the ideologies that support it, enable them to deny complex and more crosscutting mutual interdependencies-local, national, and international-and to elude their own role in creating long-term threats to their own wellbeing and that of others.