I defend my statements. The point is that if someone claims that truth is relative, they're claiming that it's really true that truth is relative. So they're making a truth claim. Their statement is internally contradictory.
That's why I ask them if what they're claiming is really true, or if it's just their opinion. Hopefully it's enough to get them thinking.
What you say is true. (ah, a truth claim). I agree with you. Multiculturalism is only a symptom, however. America is going downhill at lightspeed at almost every measurable level - universities indoctrinate rather than teach, politics are hopelessly corrupt and growing progressively autocratic, social mores are in the toilet and heading further south, and the nuclear family has been defined out of existence. All of these indicators point to a national implosion.
I am a pessimist. I give this Republic less than 15 years more to survive as we know it.