Case: You are travelling though a region of the country where donkeys are regularly cleverly disguised to look like Zebras, but you don’t know this. While driving along you happen to see the single real zebra in the whole region. So you believe “that’s a zebra”.

Q) Is one’s belief that that is a zebra based on a false belief? Do you know that that’s a zebra?

Case: You see a white fluffy animal in the field that looks very, very sheep-like. You form the belief there’s a sheep in the field. And, indeed, there is a sheep in the field. But you can’t see it.

Q) Do you have a justified true belief that a sheep is in the field?

Justified true belief:

S knows that p if and only if:

1) S believes p, and

2) p is true, and

3) S’s belief in p is justified. (This assumes that the belief is based on adequate reasons)