truthism

noun3

1. •
   A belief in the importance of truth and objective facts.

   • She [Liz Cheney] stands, she says, for truthism in the Republican Party, not Trumpism. — 2021
2. •
   (disapproving) Trutherism; the beliefs of conspiracy theorists.
3. •
   (nonstandard) A truism; something commonly accepted to be true.

   • Let's be honest: there have been times when labor unions and environmentalists have disagreed. This is no secret, and it's become one of those larger-than-itself DC truthisms. — 2015