@no1author,
Most of what we know comes from the "common stock of knowledge" that is characterised by it's being "public," collaborative, and pre-existing when we are born. It is also characterised by its non-falsifiability by those "in a position to know."
The common stock of knowledge, moreover, always carries with it an
elaborative element, a "so on and so forth" discoverable if we attend to it. I know, for example, that water is H2O, and should I have the need, I can learn about the periodic table of elements and molecular structure that would confirm it.
This common stock of knowledge, a product of human history, we accept until an event occasions us to take note by its intrusion as something "new" or "out of the ordinary" or "not quite fitting into" what we know. And then, it is by using the rules and procedures learned from the common stock of knowledge (for example, how to use a map and what maps mean, or consulting a logic textbook), that we explain to ourselves the significance of the event.