Love is here

For each of the following situations discuss why we cannot speak of them as cases of knowledge. Hence try to formulate a further requirement for us to say that A knows that p.

Suppose somebody asserts quite seriously: ''Thunder is due to the clouds colliding,'' and that he actually believes this. Why can we not say that he knows that thunder is due to clouds colliding?
At one time everyone was convinced that the earth was flat, and they could say that they knew that the earth was flat. Why can we today not say that they knew that the earth is flat?
Invent another situation which makes the same point about knowledge.

The point that knowledge requires more than holding a certain belief was already made in antiquity.
Consider the following passage from one of the dialog...