As I pointed out in “Demon-possessed or mentally ill?” Father Thomas lists several criteria which Catholic exorcists look for as a basis to warrant a diagnosis of demonic possession (or attachment). The operative principle here is Ockham’s Razor: the simplest explanation is to be preferred. In other words, if behavior can plausibly be explained by way of mental and/or physical illness alone, then one is not warranted in attributing that behavior to demonic activity.
And so the question is whether the criteria that exorcists like Father Thomas use as a guide to screen out merely mental and/or physical disorders are adequate to the task. So let’s take a look. In this article I’m going to focus on the first criterion that Father Thomas describes: an aversion to holy things. This is how he put it in the interview:
“One would be the rolling of the eyes, and that’s usually because of an aversion to the sacred. So if someone was to walk into a church or even the parish center—this has happened a number of times—walk into the parish center and they cannot stand to look at the crucifix. Or if they walk into a church and cannot stay or can only stay with great difficulty because of the presence of the Eucharist or a crucifix or another sacramental, or a statue of the Blessed Mother or something.”
Certainly, this kind of behavior is something one might expect in the instance of actual demon possession. But might one also reasonably expect this aversion on purely natural (e.g. psychosomatic) grounds? It would seem so.
A few years ago, my friend was out for lunch with a Muslim friend. After the Muslim had eaten his sandwich, my friend jokingly said, “You know, there’s pork in that meat.” To my friend’s horror, immediately the man vomited the food onto the table. So deeply ingrained in him was the Muslim prohibition of eating pork, that the response of his body was instantaneous and visceral: this was a poison that must be expunged.
If a person is familiar with Catholic culture and has consequently deeply imbibed a recognition of the holiness of particular practices, spaces, and implements, then when that individual believes him/herself to be possessed, he/she might react to those holy things with the same visceral violence that gripped that Muslim man due purely to psychological and/or psychosomatic factors.
For a particularly dramatic instance of the power of mind, consider the psychiatric category referred to as “voodoo death”, a diagnosis which is described as “the sudden occurrence of death associated with taboo-breaking or curse fear. It is based on the belief in witchcraft–the putative power to bring about misfortune, disability and even death through ‘spiritual’ mechanisms.” (Handbook of Cultural Psychiatry, 228.)
So-called voodoo death is not limited to voodoo. (Indeed, the term “psychogenic death” is far more accurate, if less dramatic.) The phenomenon can be observed across cultures as individuals succumb to a debilitating fear due to a perceived external threat, a fear that can become so all-encompassing that it results in death. (I am reminded of the classic Stephen King novel Thinner (originally published under the pseudonym “Richard Bachman”) in which an obese lawyer begins to starve — he’s unable to retain weight no matter how much he eats — as the apparent victim of a “gypsy curse”.)
Just as psychological and psychosomatic factors can bring about dire consequences resulting in death, so they can bring about recovery whether the healer in question is a traditional shaman, a new age guru, or a pastor or priest.
To conclude, it seems to me that the first criterion — aversion to holy things — is itself far too weak to be useful as a criterion for discerning true demonic possession from merely mental and/or physical disorders.
This is not to say that this first criterion is without merit. It could be substantially strengthened with the application of a scientific control that removed the possibility of psychological and/or psychosomatic factors. But how to do this? Admittedly, this is a substantial challenge given that Father Thomas notes exorcism should be carried out in a church with the priest and the presence of various holy things. Consequently, the subject will already be well aware that they are coming into direct confrontation with the putative holy things, a belief that could be sufficient to produce the aversive “possession” behaviors.
Here is one simple way that a priest might test for the presence of psychological and/or psychosomatic responses to holy things. The priest could sprinkle regular unblessed tap water on the person whilst conveying the impression that it is holy water. If the subject acts with the same aversion to regular water that he/she displays toward genuine holy water, this would provide some evidence that the ailment was mental and/or physical rather than demonic. However, if the individual acted with indifference toward the regular water but subsequently recoiled at the application of genuine holy water, this would provide some evidence of a genuine possession.