One good reason for the doctrine of stare decisis is that if judges know that their decision will bind future judges, they have an incentive to develop good rules, rather than just rules that favor a party to a particular case who may be sympathetic. If a good person driving negligently runs into someone loathsome who was not negligent at the time, rule-of-law notions require that the good person pay. It’s very hard for some people to accept that; stare decisis encourages judges to do it. Unfortunately, stare decisis in the US, and especially in the Supreme Court, is pretty much dead.
I think this idea somewhat resembles what I see as the best reason for tenure for academics: it forces those who decide whether to keep someone on to look at the merits more carefully than they might if the issue were only “shall we keep this person (whom we like, and who has cute children) on the payroll for another year even though he hasn’t written anything very good.” Academics not on the tenure track seem to have even more job security than those who have to go through tenure review.
“Belief” is a notion that isn’t necessarily tied to literal truth. Aquinas once said that “all statements about God are metaphors,” and Niebuhr (sp?) said something to the effect that “religious statements should be taken seriously, but not literally.” For a more recent (and accessible) variation, consider Tony Hillerman’s novels, in which one of his principal characters, Jim Chee, studies to be a Navaho shaman (not quite the right word, but I forget the Navaho one), taking myths very seriously without for a minute thinking that they are history. (Hillerman himself is Catholic, so he doesn’t think the Navaho myths are literal truth either.) Discussions of religious belief on this blog seem to me to assume too readily that they are just like beliefs about science or history. To some people, no doubt, they are. But not to me, and not to a lot of other religious people, either. I think there’s a bias about religion here, that needs to be overcome.
The cow thing does seem a stretch, though, even on the most sympathetic possible interpretation.