When Diversity is Bad?
Diversity is usually a strength. I'm afraid it may be that there is one case where it is a weakness.
Population and its control.
Take, for example, a revolution.
When a united group of people finds out it is being taken advantage of, and the idea pops into a few people's heads: hey, let's do something about this- the result is a revolution. It is much easier to a.) care to incite your neighbors, b.) point out the global threat, and c.) know you're speaking to someone who cares about the same cause as you- when you're all part of the same cultural group.
The United States of America lacks that. We're too large, and with many diversities. Even within one 'race', there are all kinds of different people- and in most cases these people are spread from one coast to another, and not all living in the same neighborhood.
What does that mean?
Rome was an assimilation of people- when Rome conquered an area, it added the people there to its nation. I think perhaps the reason Rome fell was not people's lack of caring, but their lack of ability to unite and stop their government from being overrun by criminals. And even if that is not precisely the case, I think that is the reason our country is getting taken to the cleaners by corporations and criminal politicians.
Our diversity is keeping us just separate enough that we don't do anything about it. A good question is, though, if that is the case, how do we fix it?