In every system of law there exist formalized rules of evidence, according to which facts have to be proven.
A party in court may be required by his opponent to prove all the facts on which he desires to rely.
Yet there must be a limit to the legal uncertainty of an endless chain of facts for which, otherwise, an equally endless chain of proofs might be demanded.
Judges have a proper and powerful way to prevent superfluous debates as to the existence of what they deem to be generally known, or to have been already sufficiently established in a number of previous cases. Such facts can be declared to have become “public”, “judicial” or “common knowledge”.
A fact so declared may, actually, be of a very complicated nature, such as a generally accepted scientific theory. The danger is, that no scientific theory is completely static, and widely accepted theories may, with justification be undermined by newer and more refined insights, but it usually takes some time until the new—and perhaps better—theory becomes generally accepted.
For that reason, theories which are in a flux, or are being competently questioned, cannot be easily declared to have been solved one way or the other. Predilection towards a particularly emphasized conception to such extent as to declare that conception not merely preferred, but “public knowledge” may foreclose for a considerable time the prevalence of better conceptions.