The notion of intentional content as distinct from intentional object is also important in relation to the issue of thought about and reference to non-existent objects. Examples of this include perceptual illusions, thought about fictional objects such as Hamlet or Lilliput, thought about impossible objects such as round-squares, and thought about scientific kinds that turn out not to exist such as phlogiston. What is common to each of these cases is that it seems possible to have meaningful experiences, thoughts and beliefs about these things even though the corresponding objects do not exist, at least not in any ordinary sense of ‘exist’.
Can the same be said of the non-existence, e.g. absence, of non-existent objects, that it has a noesis and noema? Does that absence of something have a way of appearing, in the same manner that the moon can appear half or full, or we can think of Mark Twain as Samuel Clemens?