In all taxonomies, there are lumpers and splitters. Lumpers tend to lump categories together, to find similarities, to say “these are really the same,” while splitters tend to say, no, these are different and need to be counted separately.  I’ve been thinking about the taxonomy of religions on Earth in order to think about religions on other planets. In comparative religion studies, there are lumpers and splitters. The lumpers say, there are just a few basic religious beliefs that are shared by all religions, and the splitters say, no, there is a very wide diversity of beliefs born out of a wide diversity of cultures and environments, and those differences matter. Both are talking about religions on Earth. What about religions on distant civilized planets?

We know so little about what is possible are for alien beings that we can’t even begin to theorize. The culture of intelligent life might be so drastically different that we can’t begin to speculate with any confidence. A better exercise might be a counterfactual; what kinds of religions might have arisen among our own species on this planet if we re-ran the tape of history? What if civilization began in the period before the last ice age in a different river valley system? What could the course of religions look like?  That’s a start in imagining alien religions, by imagining aliens not that different from us, but with a different set of initial conditions.

I find this exercise useful not because I expect we will encounter aliens in the near future; this is highly unlikely. It is helpful, first, because this type of self-distancing is handy in looking at our present set of religions and religious assumptions. Counterfactuals help illuminate outside conditions and other driving forces that might form the present religious regimes and continue into the future. Second, and more importantly, although contact with aliens from another planet is remote and unlikely, it is near certain we will create artificial aliens, otherwise known as AIs and robots, who might exhibit religious leanings. This exercise might hint at what those leanings might be. Although I expect our created AIs and robots to be aliens —that is not human — we will constantly try to make them more human-like, so even if they are aliens, they may wind up more like us, than say the AIs and robots produced by another galactic civilization. ( A good question of interstellar AI experts: do the species of AI and robots tend to converge (lump) or diverge (split) throughout the galaxy?)

There seems to be an axial age in human history when roughly most of the major religions started. Buddhism, Zoroastrianism, Confucianism, Toaism, and Judaism, kind of started about the same era in humanity’s history, approximately 3000 years ago. Some scholars interpret this not as the first period of innovation in religious ideas as much as the first dissemination of religions. This was the age when global trading, money, empires, and writing first appeared, which made the spread of a few ideas possible. Suddenly the same belief could be shared by millions. It was the dawn of universal religions, beyond local religions. Nonetheless, while there was some geographical overlap, each of the axial religions were independent creations. Besides these major religions there were hundreds of less durable gods from Greek, Roman, Viking, Hindu, Native American religions, to shamans and voodoo beliefs, that also have ancient roots.

So how often do religions re-invent the same thing? Popularizers (and lumpers) like Joseph Cambell extract the commonality among religions of the world. He might say there is one belief with a thousand faces (The Hero with a Thousand Faces).  I too tend to be a lumper and from my vantage, I think most shamanistic religions are very similar. Generally if you are familiar with the perspective and rituals of one shamanic religion, you’d get the essence of the rest, although the details vary tremendously. In fact, it is the details that make them beautiful. But shifting from a Shamanic religion to one based on written scriptures is a big gap with fewer commonalities. So even a lumper like me recognizes that we have distinct species of religions by now.

As a lumper I think that if a universal religion originated in a valley in the new world pre-last ice age, maybe in an alternative history where agriculture got its first flying start in the Amazon or Mississippi, we’d soon have a monotheistic religion with a sky God. But instead of it relying on harsh desert wisdom it would rely on lush jungle wisdom. The logic of plants and gardeners would rule instead of the logic of animals and shepherds. The great battles defending God would not be played out between armies on vast plains, but inside the skulls of individuals. In this religion instead of a fixation on blood, it was about identity and names.

My guess is that this new world religion will invent similar principles as its old world counterpart. As different as some aspects of the new world were, its prehistory would mostly be the same conditions: early agriculture, transitioning from hunger/gather, the very first cities and the problems of urbanity, and the new power of writing, disrupting a previous oral culture. All that will form similar notions of God, and the afterlife.

If we had to invent a religion today, from scratch, one rooted in today’s hi-technology it could fork from our familiar spiritual paths. This is another way to speculate on the religion of aliens. Imagine robots had a religion. What would they want to believe? I don’t have any answers, and it will be a long time before asking them would get a meaningful answer. Nonetheless, I think this is a productive pursuit that could help prepare us if we should ever contact other civilizations. They will surely have their own notions of where they ultimately came from.