The evidence from cognitive neuroscience research indicates that performance on different social belief tasks evokes considerable overlap in the brain regions they activate. But that begs the question whether the principles of knowledge representations of beliefs are similar to other forms of knowledge representation (for example, the rules by which words might be stored in the brain). To give a simple example, there is evidence that two languages learned at the same time have greater representational overlap in the brain than languages learned sequentially. We only have incomplete knowledge about where abstract knowledge composing social belief systems is stored in the brain and can’t say whether the same principles governing the learning of languages would hold for human belief systems. That is, would acquiring knowledge about two belief systems sequentially in time result in their representation in the brain being relatively separated whereas two belief systems learned at the same time would have a much more overlapping representation in the brain?
To stay with this analogy, language representations can be used to convey information to others about ourselves, the world, facts, etc. If we know a second language and we travel to the country where that language is dominant, we speak that second language for the same essential purposes as we would our first language. But how many people would learn a second belief system for the same purpose as the first belief system? If you practice Christianity as your religion in the United States, but then traveled to Israel, would you convert to Judaism in order to appear more socially adept in Israel? Belief systems are, to date, not used in such a flexible manner by most people.
There are few reports in the neuropsychology literature of one type of belief being affected by brain damage, but not others. Instead, we may find a set of beliefs affected by a similar underlying impairment. For example, we might study a person who has an impairment in grasping the social intentions of others and that impairment could affect that person’s ability to understand a political, legal, religious, or moral motive of someone else. This observation suggests that it is an underlying cognitive/social process, a building block of social belief, that can be selectively impaired. That deficit may differentially impair different belief systems depending on how important the underlying cognitive/social process is to that particular belief system. This differential impairment could lead to the inappropriate inference that belief systems themselves have a modular representation and can be selectively impaired. To make matters more complicated, certain cognitive and social rules tend to be recruited by a range of belief systems whereas other cognitive or social rules, such as punishment for moral violations or the acceptance of supernatural phenomena, may vary widely by practitioners of different belief systems. So, while it appears that many belief systems may utilize shared cognitive/social processes and representational space, they probably conserve some representational space for unique characteristics of the belief system relevant for the culture a person is a member of.
Although using cognitive tasks to determine whether the knowledge contained in different belief systems might be represented in a similar or dissimilar way is useful, it should also be noted that brains across cultures are not all that morphologically or functionally distinct, suggesting that some brain regions and networks should show the same pattern of activity in response to performance on tasks reflecting knowledge from different belief systems, whereas other brain regions and networks might display unique patterns of activation reflecting the unique characteristics of a particular belief system when those characteristics would be provoked by unique task demands or cues. I don’t doubt that it is these unique characteristics of belief systems that differentiate people across cultures.
A belief system may be a way to indicate the relevance of your life and behavior not only to your co-believers but to a belief-specific deity who would determine what kind of “ticket” you might have to the afterlife. Being beholden to a specific deity would take on a level of importance that supersedes the personal importance of the shared principles of different belief systems. Besides the life-death implications of this aspect of belief practice, the deity may have the same or greater importance to a practitioner than a parent or partner would have—at least compared to friends or acquaintances. There is sufficient evidence to indicate that assigning such a role to a belief-derived entity arouses uniquely deep emotions and forms of dependency.
Another reason to determine how dissimilar social belief systems are is that some may emphasize primitive elements (for example, an eye for an eye) of moral adjudication while others may emphasize abstract behavioral judgments (for example, complex moral decision-making) that indicates the path that the evolution of our belief systems has taken and the road yet to be taken.
From my vantage point, there is nothing more challenging or exciting than exploring the brain basis of human social belief systems.