But lo and behold, that’s not remotely what he said. Here is Cotton’s quote, intentionally explaining his historiographical qualms with the 1619 Project’s framing our founding, not his own personal feelings about the slavery’s role in our founding ideology:
“We have to study the history of slavery and its role and impact on the development of our country because otherwise we can’t understand our country. As the Founding Fathers said, it was the necessary evil upon which the union was built, but the union was built in a way, as Lincoln said, to put slavery on the course to its ultimate extinction.”
Even without context, it is abundantly clear that this specific assertion, “[slavery] was the necessary evil upon which the union was built,” is an opinion Cotton is arguing the Founding Fathers held, not him personally.