When TV show that introduces some spooky element wants to portray a character as "rational," the character says something like, "You know ghosts don't exist."
Why is dogmatically asserting this supposed to be "rational"? There is all sorts of testimony to the existence of ghosts, across many different cultures in radically different times and places. There is nothing wrong with being skeptical of such testimony: "Let's see the proof!" is a fine attitude. But that is a very different attitude from, "It is already known that no such proof is possible."
First of all, what about "can't prove a(n empirical) negative"? "Empirical" because we can, I think, "prove" that, say, perpetual motion machines don't exist, since we can show they are impossible. But no one has shown ghosts are impossible: how could they, when it is not even clear what, precisely, ghosts are supposed to be? If they are immaterial spirits, well, being immaterial, they might be beyond the reach of science. If they are some subtle energy released by a biological organism when it dies, perhaps we just don't know how to detect it yet.
It is good to be versed in the history of science as inoculation against the idea that whatever "science" currently deems "unscientific" will remain so for long. We detailed here how the idea of "rocks falling from outer space" was viewed by leading scientists as preposterous nonsense. Even more significant: to the foremost arbiters of what was scientific in the 17th century, Newton's theory of gravity was unscientific! It required "spooky" (i.e., ghostly!) action at a distance, something the followers of the "scientific" mechanical philosophy denied was possible. And in the twentieth century, we find Einstein rejecting quantum entanglement on a similar basis, again because of its "spooky" nature.
What the ghost issue comes down to is that a certain metaphysical view, reductive materialism, has, through propagandistic means, gotten itself associated with "rationality." And that despite the fact the following it consistently leads to the most manifest absurdities, meaning it is not rational at all!
PS: I don't "believe" in ghosts. I, personally, have never seen anything leading me to believe they exist. My attitude towards the idea is scientific: well, show me the evidence!