Anyone familiar with the Catholic faith will know that this kind of behaviour is held in high regard. It's not just Catholics either. Fanatical adherents to most of the popular faiths can be found indulging in similar painful rituals - AC Grayling has a nice round-up.
As some members of his close entourage in Poland and in the Vatican were able to hear with their own ears, John Paul flagellated himself. In his armoire, amid all the vestments and hanging on a hanger, was a belt which he used as a whip and which he always brought to Castel Gandolfo
So why do they do it? Here's the conventional sociological explanation (provided by Grayling):
Studies of self-inflicted suffering in religious observance suggest that it has two main purposes. One is the hope of rooting out sexual desire or some other physical appetite, thereby achieving purity and self-mastery, and thus merit. The other, much the main purpose, is to induce an ecstatic or transcendent state often interpreted by believers as contact with the divine.
But behavioural psychology and economics suggest a rather different explanation. Some of these I've written about before (e.g. self-punishment and costly-signalling). But I think the current front runner is something called a credibility enhancing display, or CRED.
Joe Henrich, of the Centre for Human Evolution, Cognition and Culture at the University of British Columbia wrote a very nice paper on this last year (thanks to Michael Blume for sending it to me!)
CREDs are all about communicating ideas, especially ideas that we have no way of verifying. We're much more likely to accept these kinds of ideas if we see someone acting as if they truly believe what they're telling us. If they walk the walk, as well as talk the talk.
So, if I wanted to convince you that tofu is a miracle food, you'd be much more likely to believe me if you knew that I actually ate tofu myself (despite the taste - sorry tofu fans). It makes what I'm saying more credible.
What Henrich does is to build a model that incorporates these ideas. He compares two competing beliefs that are equal in all ways except that one of the beliefs is associated with a ritual that is costly but which also enhances credibility.
The results suggest that a belief that carries no tangible benefit but only a cost can outcompete a cost-free belief, so long as as the cost is linked to a 'credibility enhancing display'.
So, if I say that God likes people to eat fine food, and you say that God likes people to whip themselves, then your version can (if the conditions are right) become more popular.
Henrich goes on to suggest that if you put this idea about CREDs together with other ideas about cultural group selection, maybe you could have a situation where practices that are costly to the individual, but beneficial to the group, could evolve. Religion might be an example of this.
So how does this help understand what's going on with the Pope and other self-flagellators? A cynic might say that he's simply trying to convince others of the sincerity of his beliefs.
By the CRED idea runs deeper than this. It acts at a subconscious level. The beliefs that get passed on are the ones that have the showiest, most costly signals.
From this perspective, it looks like the Pope was infected by a particularly virulent meme. A meme that ruthlessly self-propagates, despite the damage done to the host.
Henrich, J. (2009). The evolution of costly displays, cooperation and religion: credibility enhancing displays and their implications for cultural evolution. Evolution and Human Behavior, 30 (4), 244-260 DOI: 10.1016/j.evolhumbehav.2009.03.005
This article by Tom Rees was first published on Epiphenom. It is licensed under Creative Commons.