Let me start by saying that this is a speculative blog post. I’m a dabbler, not a historian and I am not qualified to hold much of an opinion on this subject! So, I’m just sharing some things that occurred to me, that might, or might not be meaningful.
Nomadic hunter gatherer people tend not to go in for writing. Writing calls for kit, and storing writing clearly isn’t ideal if you’d have to heft it all about with you. People who need to travel lightly tend to have oral cultures and depend on memory. Nothing controversial there.
Writing seems to go with keeping records. I’m not aware of any instances where we think a culture started writing because it wanted to keep its poems for posterity! Written records become necessary when you want to keep track of ownership and/or debt. If wealth is held in common, you don’t need records. You might need records in a larger and more complex community that is sharing resources – you might want to track that to understand what happens. So at the very least, writing represents organised and self conscious social structures, probably.
It’s very difficult to have tax without written records. It’s difficult to keep track of debt, or tithing or any other system where ownership and contribution are related. These can of course be very good things in a culture, making systems to share out the goods. But at the same time you can’t have functioning hierarchies without some kind of paperwork. Arguably the difference between a barbarian horde and a colonial project is whether you can follow through with accountants and tax the people you just rampaged over.
This leaves me with some interesting thoughts about the Celts. What are the implications of the Celts not having a written language? What does it mean about their social structures? How much of our sense of them as a hierarchical community depends on them having been depicted that way by the Romans, and by those later writing down their stories? The stories we have are full of Kings and nobles. But is that a fair reflection of Celtic peoples in Europe, or of their systems of interacting with each other? Here I am speculating, but I think it’s worth wondering about what the absence of writing might suggest.