General Discussion

a valid questionof epistemology. But it can be answered on an everyday basis - knowledge is something which has been observed or otherwise proven to be (conditionally, if one wants to be more precise) true, such as by way of a mathematical theorem subject to test - and upon the presupposition of which actions may be baed with some reasonable expectaion of a result predcted by prior experience.

You throw the ball, it moves in a parabola and it comes to rest.

The sun arises o the eastern horizon and sets on the western horizon.

A mechanical system, say a car, gives predictable and repetitive results to inputs from its controls.

Yu therefore "know" these things to be at least conditionally true for ordinary circumstances.

I amnot going to addres quantum probabilities becaue they are not applicable to macro-scale systems like cats and people, cars and ships. And while I have read extensively on these subjects I know my limits.