Optimal Exorcisms

William Butterfield of Corner Solution has a wonderful tongue-in-cheek take on a bizarre story about the rise in demand for exorcists from the L.A. Times. The section in the L.A. Times article that caught my eye was:

Only a small percentage of those in distress are judged to be in need of an exorcism, and learning how to tell the difference between demonic possession and other psychological or physical traumas is the main goal of the priestly students taking the course at the Regina Apostolorum.

"When you're dealing with a reality like the devil," said 39-year-old Father Clement Machado of Canada, "you can't just learn the theoretical. You need the pragmatic experience…. It's such uncharted territory."

I don’t doubt that it would be very difficult to tell the difference between a demonic possession and mental illness. It would take someone very wise to be able to tell the difference. Is the Catholic Church helping psychiatrics around the world so that they don’t misdiagnose demonic possession as mental illness?

William Butterfield has own interpretation for why demand for exorcism is rising: the demand for individualized prayer services.

Prayer is a service that adds value in its "production" and churches that have been able to better supply more abundant levels of personalized prayer have outperformed their more "liberal" or "traditional" competitors.


Take for example the generally more liberal and declining Episcopalian church. They pray out of a "Book of Common Prayer" which adds little individual value because, as the title indicates, nobody owns the prayer that is produced. Even the Catholic Church has lost a lot of ground to evangelical Protestants, in part because they have limited the supply of prayer to priests. Evangelicals don't do this, and they tend to pray much more often for each other and much more openly about individualized concerns. Praying openly prevents "prayer free-riding" so you can verify whether or not others are in fact praying for you.

Read his post.

I am concerned that exorcism appears to be a zero-sum game, (these little devils have to find someone to torment) and demons seem to be endogenous to the Catholic Religion. If that is the case, exorcism is essentially rent-seeking.

Of course, from an expected utility viewpoint, there might be benefits to spreading the demonic possession around: if we are risk-averse, it is better to be possessed for an hour for certain than to have a one in 10000 chance of being possessed for 10000 hours. But exorcism is a costly procedure. Therefore, there should be an optimal time that a possessed person should wait before he or she is exorcised. This would be a difficult calculation to make—perhaps more difficult than determining the difference between mental illness and demonic possession.

It just goes to show how important quality cost-benefit analysis is in even the most unlikely applications.