In the heart of the problem, I believe, is the question of causality. From the Goodman point of view, an art work, or an image in general, is always the effect of a his­tor­ic­al­ly indexed spacetime. It is thus a carrier of documentary evidence of all sorts. For the forger, on the other hand, operating with­out any such hist­or­ical indexicality, the image presents a vehicle for hist­or­ical refactures of all sorts.