I have been thinking of the idea "to know something", and find that it slips out of your hand when you try to grasp it. If I say "i know how many cousins I have" i will actually have to count first before i can say. So in a way I don't know how many cousins I have, but maybe I know that I can figure it out and then know it in a minute or so.

Anyway, as you see here, it gets a bit more complicated than one might initially think. And if you think about it, the problem that I show by my example above is basically there, if not for all, at least for many of the things we normally say we know.

So, considering this, what does it mean to actually know something?

If we go in the other direction, and accept every information that we have in our mind to be part of our knowledge, no matter how long it takes to retrieve, then we run into other strange things.

Like, then we can say "I know what digit is there at position number 1 million in Pi", simply because we know how to figure that out. Or we could even stretch the concept and say that we know everything that we have access to, be it in our mind or elsewhere, like on the internet.

So, with that idea we can basically say that we know practically everything.