[Borges]

History has shown that multicultural/multiethnic societies are basically unstable.

Multicultural yes, multiethnic no.

[Clemenza]

Correct, Brazil is multiracial, and has no racial majority as a matter of fact, yet there haven't been any "race wars" since indenpendence.

New York has been a "majority minority" city since the mid-80s. Effective law enforcement and high real estate prices seem to be the factor in "keeping the peace" there, to say nothing of the fact that immigrants to NYC typically learn enough ghetto English to function in a multiethnic society.

[Free Dominoes]

As Thomas Sowell stated, multiracial countries don’t work unless one group is dominant.