If, as I argued in the last post, believers believe silly things in order to make the community cohere in the face of competing loyalties of the wider community, why is it that they believe the things they believe?
For example, you will often see Jews attempt to argue that kashrut (kosher, in Yiddish) dietary rules make sense in arid environments where trichinosis was rife, and so on, but what is the reason why you can’t mix fabrics, or get tattoos? The reason appears to be that these marked the Jews out from their competing cultures. An approach taken by recent Cognitive Science of Religion (CSR) scholars adopts the “costly signalling hypothesis” formulated in evolutionary biology by Amotz Zahavi and applies it to the cultural evolution of these kinds of displays. Zahavi’s hypothesis supposes that if an organism is signalling its toxicity to predators or genetic health to potential mates, it can easily fake those signals. Evolution, however, is a hard mistress, and will weed out these easy-to-fake signals over the long term, as any variant predator or mate that tricks on a way to detect fakes will spread rapidly through the population, causing an arms race. So in the long term, signals of whatever property is being signalled will have to become hard to fake. Zahavi suggests that behaviours like stotting will have to honestly signal the fitness of the organism.
So there are several properties for a costly signal. One is that it costs more to fake than to simply have the right property. Another is that it must correlate with the right varieties. Another is that it must be arbitrary: it should not be a trait or behaviour that is selectively advantageous, or many different varieties or organisms will trick upon it, and it will not therefore correlate. So an honest, costly signal is an arbitrary signal.
CSR researcher Richard Sosis proposed that many of the doctrines and institutions of religions are such costly signals. Kashrut is arbitrary, because it has one function: to mark out, uniquely and honestly, Jews from their (genetically related) neighbours. This is not biological evolution, but cultural evolution – what evolves are institutions, rituals and behaviours. They function as what I call “tribal markers”. They include accents, languages, dress, diet, and a host of other things. Consider the ban on pork by Muslims and Jews: here is an easy to raise food resource that is foregone to identify themselves. It is hard to fake if food is not plentiful. Circumcision and scarification among various groups is another kind of costly signal. People can die from these rituals. That is the ultimate genetic cost.
So the reason why (or if you prefer a pluralist approach, a major reason why) religions have these silly beliefs is that they serve to honestly signal identity. But this doesn’t explain why they have these silly beliefs. And extending the argument to all kinds of belief-systems, it fails to explain why belief-groups settle on the particular beliefs they do as the tribal markers of identity.
One suggestion is that these are simply contingently adopted. For example, the use of some “shibboleth” like abortion or the use of tattoos or tassels may be a simple matter of an idea being proposed at the right time and taking off, as a fashion, so long as it involves all the right costs. There may be no other reason for it. “Shibboleth”, by the way, is an example from the Tanakh:
For the rest of the story: http://evolvingthoughts.net/2014/01/why-do-believers-believe-those-silly-things/