ABSTRACT
Suppose that you are watching a play and the back of the stage appears to look out on a garden with a tree. Actually there is a large backcloth bearing a photograph lit in such a way that you cannot see from where you are sitting that it is merely a photograph. Furthermore there really is a garden with a tree behind the stage, and if the backcloth and stage wall were not there it would look just the same to you. But in this case you see the backcloth, not the tree in the garden, because your perception is not caused (in the right way) by the tree in the garden. If the photograph is a photograph of that very tree, there is of course some causal connection between the tree and your perception, but it is not sufficient to count as your seeing the tree rather than the photograph. This is shown by the fact that it would make no difference if the photograph were of another scene coincidentally indistinguishable from that behind the stage wall: you see the photograph, not the tree.
