What are the positive and negative attributes of nationalism?

Positive: People within a nation overcoming their differences for the common good, Overthrow of Colonial rule, Democratic governments in nations throughout the world, and Competition among nations spurring scientific and technological advances.

Negative: Forced assimilation of minority cultures into a nation's majority culture, Ethnic cleansing, such as Bosnia and Herzegovina in the 1990s, Rise of extreme nationalistic movements, such as Nazism, and Competition between nations leading to warfare