Final answer:
Thomas Jefferson believed in racial inferiority and segregation, contradicting the notion of racial equality and diversity, despite his words on all men being equal in the Declaration of Independence.
Step-by-step explanation:
Thomas Jefferson, despite his relationship with Sally Hemings, held views on race that are now considered deeply problematic. In his book Notes on the State of Virginia, Jefferson articulated a variety of claims about race. Among these, Jefferson believed in the racial inferiority of Black people and thought they were unfit as citizens because of perceived intellectual differences, thereby contradicting the idea of racial equality. He advocated for racial segregation by endorsing the idea that, upon emancipation, African Americans should be colonized outside of the United States. His writings do not support the notions of racial diversity; rather, he feared racial 'mixture' and supported the preservation of white racial purity. Consequently, the ideas that Jefferson believed in include racial inferiority and racial segregation but not racial equality or diversity.