Cognitive Biases That Undergird Tribalism: The Polarized Mind
"In-group favoritism, sometimes known as in-group–out-group bias, in-group bias, or intergroup bias, is a pattern of favoring members of one's in-group over out- group members. This can be expressed in evaluation of others, in allocation of resources, and in many other ways. This interaction has been researched by many ..."
source: In-group favoritism - Wikipedia
"A cognitive bias is a mistake in reasoning, evaluating, remembering, or other cognitive process, often occurring as a result of holding onto one's preferences and beliefs regardless of contrary information. Psychologists study cognitive biasesas they relate to memory, reasoning, and decision-making."
Video: Enlightenment Now | Robert Wright & Steven Pinker [The Wright Show]
Some food for thought.