Prejudice and Discrimination...

Prejudice and discrimination are negative manifestations of integrative power. Instead of bringing or holding people together, prejudice and discrimination push them apart. Ironically, even prejudice and discrimination imply some sort of relationship, however. If there is no relationship people would be completely unaware of another person's or group's existence. When there is any relationship at all--even a negative one--there is some integration.

Kenneth Boulding referred to this as "disintegrative power"-"the integration that is achieved through hatred, fear, and the threat of a common enemy." (Boulding, 1989, p. 62.) This is seen in military patriotism, in nationalism, and in any situation of "negative identity" in which one group defines itself in terms of what it is not. This tends to lead into a "pathological situation of internal violence, often perpetuated through the family itself." While this is especially obvious and destructive when it occurs on a large scale--as it did in the Balkans, Somalia, Sri Lanka, or the Middle East--it also occurs on smaller scales as well, when one group holds negative stereotypes of another group and discriminates against members of that group based on those stereotypes.

http://www.colorado.edu/conflict/peace/problem/prejdisc.htm