How Would We Know If Ghosts Exist?

Fantasma de la curvaCan Halloween please get here already? This will be the third post about ghosts I've written in the past few weeks (the first was Do Ghosts Have To Be Supernatural? and the second was Do Ghosts Require the Christian God?). I'm all keyed up for Halloween (and Jesusween) now. Anyway, I wrote something in one of the recent posts (or maybe it was in response to a comment on one of them) about how anyone truly interested in pursuing the possibility that ghosts are real needs a decent theory upon which to base a scientific investigation. I thought I'd try to unpack what I meant a bit in this post.

When you watch one of the many ghost hunting shows you can easily find on cable TV these days, you see lots of sophisticated-looking equipment. Those using it claim it can help them demonstrate the existence of ghosts. But what theory of ghosts is being tested? It is not at all clear to me why the equipment selected is ghost-relevant. Why, for example, would an instrument capable of detecting magnetic fields tell us anything useful about ghosts? Why should ghosts generate magnetic fields? Why would infrared or thermal imaging cameras be helpful in allowing us to detect ghosts? The list of questions goes on and on. Without a clear theory of ghosts, we don't have a clue how to detect them or why any of the so-called detection methods that are supposed to impress us should be effective.

Suppose we had a theory of ghosts that produced a number of testable hypotheses. Now suppose that one of these hypotheses indicated that a ghost passing through a room would typically cause the temperature of the room to drop by roughly 10 degrees F and that this drop would last for at least a few seconds. It might make sense to test that with a variety of instruments that could measure rapid temperature changes. But without such a theory, it looks like little more than a fishing expedition. We take a bunch of random measurements using all sorts of equipment, detect an anomaly, and conclude that we found ghosts. This is not how science works.

Starting with a coherent theory and doing some rigorous hypothesis testing would put us in a much better position to support, disconfirm, or revise our theory. Of course, I recognize that most of the "paranormal investigators" we see on TV have little interest in science and would not risk disconfirmation of something so lucrative. In that respect, they are more like religious believers than scientists. This is one of the things that makes pseudo-science so misleading; it looks like science but it isn't.

In a way, this is kind of too bad. Although I do not believe in ghosts, I think it would be kind of cool if they were real. And if they were real, I'd like to know about it. With the current approach, I'm not sure we'll ever be able to say that we've done the sort of investigation that might close the matter. Not unlike gods, the rational course would appear to be one of concluding that they probably do not exist. At the least, we don't have anything close to the sort of evidence we would need to believe in them.