I've been listening to Dawkins' 2003 Tanner lectures at Harvard. I'd like to share a point Steven Pinker made in the seminar session:
Group solidarity benefits individuals to the extent that defectors and cheaters can be controlled. A group of people acting together can enjoy a number of benefits of cooperation, but are always vulnerable to those who would seek to enjoy the advantages of group membership without contributing to the common welfare. Policing possible cheaters and defectors is the fundamental problem in group living among non-relatives. Religious systems often exploit our emotional and cognitive faculties in order to weed out defectors, to make sure that people who are enjoying the group benefits pay their cost. One of them is public costly commitment. That is, to become a member of the group, you have to prove you're willing to contribute to the common will by publicly making some sacrifice that is genuinely costly and genuinely hard to fake: sacrificing your best animals, your best crops; as in the story of the binding of Isaac, your son—in real Jewish tradition, you hand over your newborn son and say, "Go ahead cut off a piece of his genitals." Only people who are pretty serious about being a member of the group will be willing to make such a sacrifice and those kinds of blood sacrifices are a ubiquitous element of religion as a commitment device.
I still have the habit of framing this sort of statement in the context of my own recent beliefs, so here goes: the commitment devices of Jehovah's Witnesses include separatism, adherence to group rules, engagement in preaching work, and attendance and participation at religious gatherings. Involvement in these (physically, not directly financially) costly activities is considered evidence of "spirituality", a quality that wouldn't be quantifiable or practically definable otherwise. True, this leaves an unfortunate gap for those sick and elderly who are unable to demonstrate their own spirituality through some of the more physical activities, especially preaching, which is a vital element of the belief system. Jehovah's Witnesses' literature recommends that such ones be treated consolingly. Of course, human attitudes vary in practice and some are less capable consolers than others, but physical illness actually provides further opportunity for healthy Jehovah's Witnesses to evidence their spirituality by aiding the needy; a commitment device that contributes to the needs of the group.
When learning about game theory, I only considered two-actor scenarios in which a consistent cooperator is worse off when confronted with a consistent defector. But unrequited cooperation can find rewards within group situations to the extent that demonstration of a cooperative attitude is recognized by other group members. Care and treatment of the sick and elderly can be one example of this: unhealthy individuals may be unable to reciprocate, but the donor may earn affection and thus further secure a position within the group.
Pinker's examples were all wasteful activities, which he called blood sacrifices, but most of the commitment devices I've described so far have obvious benefits for the group: separatism insulates group members from outside ideas; rules help group leaders identify and correct or remove defectors; preaching expands the group. But these activities all come at great cost to individuals, and some of the specific rules (famously, refusal to accept blood transfusions) do seem wasteful in the immediate term.
I think the last few words of that last paragraph deserve special consideration: Jehovah's Witnesses and other religious groups believe their commitment devices are beneficial in the long term, afterlife, or resurrection, and some religions advertise short-term benefits to help support odd practices. Jews, for example, advertise the health benefits of circumcision and risks of contracting parasites from forbidden meats, while Jehovah's Witnesses claim health risks related to blood transfusion. These benefits may not be true, but they are believed to be true, which eases acceptance of the practice itself. As I discussed in a previous post, the success of a religion depends on its having some beneficial precepts. Pinker has articulated that precepts with no apparent benefit may still be helpful as commitment devices, though commitment devices aren't necessarily wasteful.
