It's an open question in the Catholic faith.
And there are large numbers of Catholics who believe in ghosts due to the fact that the apostles thought Jesus was a ghost after the resurrection.
I think that apparitions can occur.
But these apparitions are exceedingly rare.
And they don't happen the way they do in the movies. Souls do not haunt murder scenes or other spooky places to expiate their sin or to take revenge.
So for all intents and purposes, ghosts don't exist.
I think what people mistake for ghosts could be demonic manifestations.
So I agree with Dan Burke.
