This chapter answers the age-old question of what causes us to form social groups and why they are important. Social acceptance and interactions were crucial to our evolution but not all aspects of it are helpful. Consider UFO sightings
This a great example of what can go wrong when you rely on the group too much. The group assumes that UFO's exists and through the use of confirmation bias they discount data that proves them wrong ( satellites, other planets, military aircraft, etc.)
However there are other times when it makes sense to listen to the group. If you are less informed on an issue and the group is more informed it makes sense for you to listen to them over yourself even if they might be wrong. psychology teaches us how to evaluate the situation and whether we should support the group or dissent.