Today is International Mother Language Day, a day set aside to recognize the importance of minority and endangered languages and to celebrate cultural and linguistic diversity.
I recently had a conversation with my middle son about what it means for a language to be dead. This came up because we were discussing Irish (which we are both learning) and Latin. There are more people who can speak Latin than there are people who can speak Irish, but Latin is a dead language and Irish is not quite dead yet. The thing that makes a language dead is when there is no longer a community that speaks it as their primary language. What follows is my theory of how languages evolve and what it means for them to be alive.
For a language to be truly alive, it has to be reinvented by every generation of its speakers. Children learn language from their parents until they are about 5 years old, and then they invent the rest of their language with their peers. This is why irregular verbs and plurals in English are all common words that young children learn, because when they invent the rest of the English language they don't bother keeping words irregular. Languages have a continuity because the peer group that children invent their language with includes people up to about 5 years away from them in age, so there is a continuous chain of language invention. Additionally, children are inventing their language in the presence of many adults who invented almost the same language some time earlier, and they copy the adults when they don't have any better ideas.
This is why slang evolves so rapidly. Words to express that something is fantastic (such as awesome, cool, and radical) are continuously replaced by children who want to express that their concept of what is fantastic is different from the adults' concept, so they deliberately use different words. Slang has also often been used as an intentional obfuscation, where people are speaking in code that the adults/authorities don't understand. There are many recent examples of this from China, where discussion of certain topics is banned, so people find ways to have conversations that appear to be about something else.
This is also why written languages change at a much slower rate than spoken languages. People do not generally reinvent the concept of writing with their peers; they are taught to write in schools or by tutors. Their teachers teach them the same written language that they learned, with adjustments strongly discouraged. An interesting recent exception to this is texting, where the kids are inventing a new written language with their peers.
A native speaker of a language is someone who re-invented the language with their peers. Anyone who did not participate in this process can at most be a fluent speaker of the language. This is why even though many immigrants to the United States try to teach their children their native language, their language is rarely passed down to the grandchildren of the immigrants. Because without a community to re-invent the language with, the children of immigrants never become true native speakers of the language, no matter how much they speak it with their family.
This is also why Latin is a dead language. Because there is no community of children re-inventing the Latin language as a community. Even if they tried to, the utility of Latin comes primarily from being able to read things that were written long ago, so new variants of Latin would not spread. New words can be added to Latin, but unless a community is built up raising their children to speak Latin together, it can only ever be a dead language.
A minority language can only survive for as long as a community can maintain its regular use amongst its children. Because once the children stop re-inventing the language on a continuous basis, the language will die even if there are still people who can speak it.
It is possible to revive a language, but the language will always be different after the revival. Normally children are inventing a language with native speakers 5-10 years older than they are contributing traditional words and grammatical features. But with a language revival, the first group of children to revive the language don't have older peers to guide their way. Instead, they will be inventing their language with guidance from adults who are making an effort to revive the language.
In this way, language is like many other aspects of culture. The living aspect of culture is necessarily like an oral tradition. People can describe cultural traditions, ceremonies, and practices in books, but the living thing that is the culture itself can only truly be passed on by having each generation grow up practicing it and reinventing it - taking the parts they like that seem relevant to their lives and adjusting the parts that they need to adjust.
