From my article on the classic ghost-story writer M.R. James:
Do you believe in ghosts? Montague Rhodes James kept an open mind: “I am prepared to consider evidence and accept it if it satisfies me,” he once commented. …
Even hard-headed skeptics must have moments of uncertainty. There is no rational reason to avoid walking beneath a ladder, only a superstitious one. But who doesn’t think twice about doing it — or breaking a mirror, opening an umbrella indoors, or letting a black cat cross your path? “Everyone can remember a time when he has carefully searched his curtains — and poked in the dark corners of his room before retiring to rest,” wrote James. Better safe than sorry.
Dickens probably put it best: “My own mind is perfectly unprejudiced and impressible on the subject of ghosts. I do not in the least pretend that such things cannot be.”