Well, for one thing none of these experiences has, so far as I know, ever been scientifically confirmed as an actual out-of-body event. At best, the evidence has been inconclusive, as in the case of the widely-reported AWARE study. In addition, there are reasonable alternative explanations for such experiences (in part arising from the fact that the experiences occur in many different situations, such as during sensory deprivation or as a result of hallucinogenic drugs). A third consideration that isn’t as often discussed, though, is this: how a priori reasonable is the claim that these are actual out-of-body events? Or, to put it in Bayesian terms, what is its prior probability?
I would say it’s very low. The main reason is that there is good evidence that mental events are at least dependent on brain events, if not identical with them, as I've previously argued here. But there’s another reason. The experiences that people report are in a sense suspect. I don’t mean these people are lying; I’m sure the great majority, at least, really experience something. What I mean is that there are certain aspects of the experiences themselves that suggest they aren’t out-of-body events.
Consider the fact that people commonly report seeing their body as if they were floating above it. Is this what one would expect a non-physical mind that’s escaped the confines of the body to do? Well, for one thing, the non-physical mind doesn’t have any eyes. Moreover, it is invisible (no one has ever seen one of these spirits escape from its body while on the operating table), which means that light goes right through it. Thus, it cannot capture any light coming its way so as to form an image out of it. How then can it see anything? (The situation is much the same in the case of the invisible man from science fiction stories. Why isn’t he blind?)
One possible answer is that the floating mind has an experience that is as if it were seeing, just as we can have in a dream. But even though that’s a possibility, it’s not very plausible. The way we see things has a lot to do with how our eyes are structured, which explains among other things the range of wavelengths that are perceptible to us. Without the eyes as the organ that captures visual information, why would the floating mind have an experience that is exactly like that of a normally functioning human being? Is it just coincidence that the floating mind happens to capture the same wavelengths? That it cannot detect, say, ultraviolet light? And why do these floating minds have a field of vision that, again, is just like the kind we have with eyes? Why don’t they have, say, 360-degree vision? For that matter, why don’t they see outside their operating room (without actually moving through the walls, that is)? Or inside the bodies of the medical staff? After all, if their vision isn’t due to capturing light, why would the opacity of walls or skin make any difference?
Think how much more convincing the report of an out-of-body experience would be if the person claimed their experience was utterly unlike anything they’ve ever seen in waking life or even in a dream. Then we’d have to wonder how their minds could have made up such a strange idea. As it is, the likelihood that these really are out-of-body events seems rather slim.
[Originally published at Debunking Christianity]