The phrase "established fact" refers to something that is widely accepted as true or proven beyond doubt. It means that there is clear evidence or confirmation to support the fact, making it widely acknowledged. Full definition
One of the best established facts of educational research is that the educational background and aspirations of fellow students significantly determine what a student will achieve. (religion-online.org)
My lecturer taught me to always establish the facts in support of an article's title. (justarsenal.com)
-- your saying «most scholars» does not establish fact and certainly is contrary to written record. (religion.blogs.cnn.com)