Is there a word for an idea similar to negative evidence?

Question

My question will best be summed up by this phenomenon.

A few thousand years ago, all Jews believed that the tablets containing the ten commandments were square, there was no debate regarding their shape, and therefore, no one ever wrote what their shape was. They described their size, and how they fit in a square box perfectly, but they never bothered to explicitly mention whether the tablets were round or square.

So I'm looking for a word or a phrase that describes the phenomenon of something being so obvious that no one bothers to write it down.

Answer 1

It sounds like conventional wisdom

the body of ideas or explanations generally accepted as true by the public or by experts in a field. Such ideas or explanations, though widely held, are unexamined.

Wikipedia

The term given (as a noun) can also apply

an assumed fact

Collins

Answer 2

The term I would use would be default position, borrowed from wordprocessing, though the only example I have is from a Wordpress page.

The term “default position” refers to a belief (or lack of belief) that is preferable prior to debate or before any evidence is considered.

Answer 3

Historians and the like call this tacit (or implicit) knowledge - things that were considered so obvious no-one ever bothered to write them down, but which may not be at all obvious centuries or millennia later.