From Bobby Jindal at The Wall Street Journal, The Roots of Political Polarization 

The left sees people primarily as members of groups defined by race, class, sex and sexual orientation. They are therefore confident that demographics are destiny. Individual agency is de-emphasized on the left and pure merit-based systems are dismissed as self-contradictory, as President Obama alluded to in his infamous “you didn’t build that” remark. The left assumes that the presence of disparate outcomes proves inherent bias requiring state remediation, even where proof of intent or even deliberate action is absent.

They are confident a more diverse America will be a more liberal America. When minorities adopt views different from the liberal orthodoxy, such as Asian-American students suing Harvard for discrimination, liberals denounce them as “whitening.” Asian-Americans who reject liberal views are disparaged as “Twinkies,” and African-Americans who do so are called “Oreos.”