"All lives matter" was a racist position from the start. To say "Black lives matter" is to utter something deeply subversive in American society--that the lives of African-Americans should matter to the same degree as the lives of white Americans. To say "Black lives matter" is to assert that "All lives matter" because the lives of African-Americans have historically been valued only as chattel or devalued (when they could no longer be enslaved) via segregation. It was white Americans who wrote the laws that Black lives didn't matter or mattered less. America has "progressed" from de jure racism to de facto racism. Many white Americans need to bring their mentality into the 21st century as the rest of the world is leaving them behind.