rationalist

Noun

rationalist (plural rationalists)

1. A person who follows the philosophy of rationalism.
   • “He says,” replied Lord Peter, “that he believes Hannah to be a sincerely religious woman. He has sat beside her in chapel and shared her hymn-book.” “But that may be the merest hypocrisy,” said Miss Murchison, rather warmly, for she was militantly rationalist. “I don’t trust these unctuous people.”1930, Dorothy L. Sayers, Strong Poison
2. A member of the rationalist community.
   • Some rationalists were in touch with Oxford philosophers, including Toby Ord and William MacAskill, the founders of the effective-altruism movement, which studied how to do the most good for humanity (and, by extension, how to avoid ending it).2024 March 18, Andrew Marantz, “О.К., Doomer”, in The New Yorker, page 45