From what David said today, it sounds as though he does indeed see ghosts, as he has said before. Roger and Elizabeth aren't really sure if they've seen ghosts or not; all they know (if I remember their conversation from the other day correctly) is that they've seen things they can't quite explain, which could mean anything or nothing. Carolyn gives no indication of having seen a ghost; she talks about them, but not as if they were anything she had experienced. But David apparently believes he has seen some. Did he see something like what Roger and Elizabeth have seen - something which can be pretty much rationalized away when he grows older? Or did he really see something definite and undeniable? And if he saw something definite and undeniable, why was he so favored? Do ghosts have any control over who can see them? Bill Malloy's ghost spoke to Vicky - but wouldn't Bill have preferred to speak to Elizabeth?
David says Josette didn't jump off of Widows Hill; she was pushed. Is that what he wants to think, or did she communicate that to him? And who pushed her? Did Jeremiah get tired of having a broody wife? It's sad to think that, if she was pushed, her murderer got away with it.
Carolyn says that David drowned a kitten that he loved. We have been given to understand that he loved his mother as well, and that she's in an institution. Cause and effect?