Since so many of my acquaintances know me as “that skeptic guy”, it’s not rare for one of them to challenge me with an experience they had, often reporting something like a ghost experience and saying “Disprove THAT, Mr. Skeptic.”

Of course, this completely misrepresents what I do, and where the process of skeptical science leads us. I’m far less qualified than my friend to prove or disprove his ghost experience; I wasn’t even there. In fact I’m always a little disappointed to find that my friends think I’m obsessively out to tell people that they’re wrong. If there is one thing that obsesses me, it’s the challenge of finding solutions to interesting mysteries — and telling people that they’re wrong is not relevant to that process. Proving alternate explanations wrong is collateral damage when a mystery is eventually solved, but it’s never the goal.

Yet, plenty of unsolved phenomena exist, and so the field for possible explanations remains wide open. Perhaps some strange experiences are caused by ghosts. However, I don’t think that’s a very satisfactory hypothesis, and the main reason is that the rationale for the existence of ghosts is — forgive the term — illusory.

Here, in brief, are a few of the reasons I give most often why it’s never right to jump to the conclusion of “It was a ghost”:

There is no theory in any life science that makes a prediction that ghosts exist. Ghosts have no properties that can be described. There has never been a reproducible ghost event. This makes it unlikely that the perceived phenomenon was a real one. The logic that most people use to arrive at a conclusion of “ghost” is faulty. It’s usually “Something inexplicable happened, what else could it be?” A ghost is an unknown. By no logic can a set of unknown properties be considered consistent with your experience. Any other unknown – leprechauns, sorcery, Bigfoot – is an equally valid match. No evidence of ghosts exists. Evidence of strange events exists, but see #4 for why we can’t say what it was. “Unexplained” ≠ “Explained as a ghost.” When searching for the explanation for a strange experience, a process of elimination of causes can never logically leave “a ghost” as a reasonable explanation. See #4 above. It’s OK to say “I don’t know what that was, that was really weird.” In fact, a genuinely unsolved mystery is always more interesting than a wrongly solved mystery.

Maybe ghosts do exist; I certainly don’t deny the possibility. But I submit to my ghost believing friends that, by making the conclusion prematurely, you are doing yourself at least two unkindnesses:

You’re missing out on the excitement of solving a real mystery. By stopping at “It was a ghost”, you are robbing yourself of the rest of the journey. You may be missing learning about some cool new perceptual error or state of consciousness that you didn’t know about. There may be an engineering, optical, electrical, or auditory sensation that’s really neat. You’ve stopped at a detour that almost certainly leads nowhere. You’re making your world really complicated. By shoehorning the idea of “ghost” into what we know of our world, you’re breaking up established theories of life, consciousness, neurology, probably others, and re-assembling them into a patchwork theory of the world that no longer accommodates all the things that we do know.

Don’t look at the world through goggles that are broken. Instead, learn to say “I don’t know” and keep your goggles in one sound piece. You’ll be far better equipped to understand and interpret your next mysterious experience.