# How to make a language evolve quickly?

Imagine a world in which the language barrier is a means of propaganda defence.

In this world, one of the primary concerns of each country is the migration of natives, since they know their native language and can function as translators.

Let us assume, for the simplicity of the question, there is no publicly available written medium, and only spoken languages exist. (No newspapers, no books, no written signs on shops etc.)

The nations must therefore change their language as much as possible before the other nations can train a force of translators (who may be able to keep up with the changes if they were sent to spy).

The nations are large enough that it is administratively impossible to make sure all citizens are using the 'current' language.

How do these nations make sure their language becomes incomprehensible for someone who left it 10 years ago?

This question disregards the long-term effects such a procedure could have.

Technology level is modern.

• I'm on the fence about this question. Changing your only way of communication for an entire nation will be driven by your stories needs. Any changes to a language need to be given to the public... ever member of the public to allow it to propagate. If a languages changes too fast you will end with different dialects as the changes won't be passed on 100% effectively. Rather than have a united nation, your creating your own version of the tower of babel – Shadowzee May 9 at 7:48
• "there is no written medium" seems to be in contradiction with "Technology level is modern". I don't think you can have both of those, since modern technology is completely dependent on sharing detailed knowledge not just between people who are there right now but also across a time barrier. I doubt you can even make a tape recorder without relying on some kind of written information at some point. – a CVn May 9 at 8:17
• No publicly-available written medium is a complicating assumption, not a simplifying assumption. No fixed medium would be simplifying. All writing is digital would be simplifying since written language updates could be pushed out through software updates. If it takes 10 years to update all computers in the country, that's still better than real life. – Lofty Withers May 9 at 9:23
• Writing makes your scenario more complicated because older iterations, whose truth predates the current political version of truth, still exist, can be accessed and can't be changed. Putting everything into digital format and destroying the paper versions gives your governments control over the shape of truth. You might want to read Nineteen Eighty-Four; as quite a bit of your question is answered there. – elemtilas May 9 at 14:46
• I think there are too many flawed assumptions in this question: The idea that you can have a language which is both secret and commonly known; the idea that you must train teams of translators rather than simply grabbing native speakers off the street and forcing them to help you; having modern technology without written language; being able to prevent people from learning languages other than their own. – barbecue May 10 at 21:12

Generate a constant stream of scandals that make common expressions politically incorrect.

Add aggressive prosecution of people using oldspeak because you want to avoid offending the party that phrase now insults and you have a built in way to root out spies.

• That is so 1984. – Lofty Withers May 9 at 8:56
• @LoftyWithers I'd even say its 2019... (yes i got the reference). – Dylan May 9 at 20:20
• I heard about a real culture actually doing that. Some natives name their children after everyday things like animals and plants. But when the people die, their name is now offensive, because it brings back grief. So they constantly have to rename their things in order to avoid that. Maybe someone can find a reference to that (It should be on youtube and mentions that you can fix the grief you caused when using the w̶r̶o̶n̶g̶ old word with money). – nwp May 10 at 13:31
• – dan04 May 11 at 2:47

We are a good halfway to that. You just need to increase the communication rate, so that language mutation happens more often. Also give a generous spread of technological advancement.

Take a simple sentence as example:

Lol, I have been pwned. Ping me on WhatsApp.

I get it, you get it. Should my grandparents be alive and should I tell them that sentence, they would look at me with a puzzled expression in their face. How did that happen?

Communication, thanks to the internet, got more frequent and highly paced.

If semantic mutations happen once every few million words exchange, by increasing the number of words exchanged in a given time you are just increasing the number of mutations in that time. Push this forward, and you will get a way faster evolution of the language, to the point where it will be hardly understandable by an outsider.

• And of course you could speed up that process A LOT if the media - which in our world slows down that language-change by mostly sticking to standard english - were on board with the new expressions and used them extensively (and maybe almost exclusively). 10 years might be a bit much to make it completely ineligible, but the exiled translator would have serious trouble and will probably not get implied information, sarcasm etc. After 20 years they might get no info at all anymore – Hobbamok May 10 at 8:45
• And worse if you think that being english the primary communication language, this is how it is said in Spanish: "LOL, Me han Powneado, Chateamos en Whats" (Although I have to say these three words 've heard, but never the three on such a short space). Other words that entered spanish vocabulary through the same medium: "güifi", "tuit", "clicar", "computadora", "email", "web", "internet", but also "noob", "gl", "WTF", "swish", "META", "griefer", "troll", "hack" (and "hackear")... – Stormbolter May 10 at 9:45
• Or make the generations come (but maybe not die) faster. This way, you could get more rate of change while still having the same ratio of new words per generation, to keep it understandable. – RudolfJelin May 10 at 10:54
• This gets more effective the more Darmok the language is, especially if everyone follows the same media. (Katori asks if memes are language. F. Shocked Pikachu.) – that other guy May 10 at 20:46

You Can't.

Language evolves to be sure; there are words in the English language today that weren't in it when I was in school, and we pronounce (and even in some rare cases spell) some words differently to what we used to even in my lifetime.

The thing is, even disregarding the anchor point that writing provides to a language by its very existence, the single limitation on the alteration of language is the ability of the populace to learn the alterations.

As toddlers, we learn language through imitation and it's only later that we ascribe meanings to specific sounds and we build semantic structures in our minds around those sounds. We learn to manipulate our environment and others through the use of our voice and then we learn that we're using words and a language and our world opens up. Then we go to school, and in terms of language, we do two very important things;

1) we learn the written form of our language, and
2) we build on our vocabulary.

This last one is critical. Without it, we can't build the nuanced semantic concepts that allow for the great precision needed in describing the subtle differences between (say) momentum and force. We can't build deeper understanding of the arts, we can't learn that Chartreuse is a subtly yellow form of green. Worse, this doesn't stop at school; we build our vocabulary to account for even more subtle forms of precision, and incorporate new words to reflect new concepts in our technology, culture and environment.

In every way that counts, Brexit is indeed a word and any Briton or follower of international affairs knows exactly what you mean when you use it in its correct context.

In your world however, you're effectively forcing people to start at the bottom rung of the linguistic ladder on a constant basis. First of all, it's not altogether clear how older minds would face having to learn a language all over again on a regular basis. Second, what you're going to prevent is the ability to build those nuanced and subtle points of precision that specialists rely on during their career. Language will remain simple because by that very defintion, it's going to be easier to relearn, meaning that you've just killed off all the pursuits and benefits that you're trying to protect from foreign agents.

In English, there's something called the Rule of 5s;

There are approximately 500k words in the English Language
The average person has a vocabulary of 50k words in English
The average person uses approximately 5k words in their speech in English

(This may be different now; I was taught this in linguistics a long time ago.)

My point is, having to constantly relearn those 50k words will be painful, and ultimately most people won't be able to do it. Can you change the language over the course of a single lifetime? Sure. It happens all the time (when speaking in terms of centuries), but older people will still carry certain elements through with them to the younger generations, so each will be understood by the other. But can you do it in years? No. Humans need to use the foundation of language they build to understand and build upon, meaning that constantly changing that foundation leaves you with nothing built on top of it.

In point of fact, your nation is actually leaving itself more exposed to propaganda, not less. The single largest trick in propaganda is to over-simplify a problem to make it look like your simple solution is so obvious and that the competing administration is too foolish to understand it. But your nation now is only capable of understanding the over-simplified answer. Ultimately, the implementation of your strategy is an own goal.

• I think the specific numbers are a little off, but you have the right orders of magnitude (10^3, 10^4 and 10^5). – Tim May 9 at 12:50
• Obligatory xkcd link: Up Goer Five – a CVn May 9 at 14:41
• entually you just hit the limit of a human lifetime, you can't change a language so fast peole who learned it as children cant understand it in their 90's. After a certain age people just don't pick up languages easily. – John May 9 at 22:50
• It should be also noted that when a language evolves then the evolution is not random, it has a cause (e.g. omitting syllables to make a new word when speaking fast, common writing typos, influence of other languages) and the evolution can be tracked because no word changes randomly. – Sulthan May 11 at 16:42

# The Church manages the transformation through hymn and prayer.

When the mandated Sunday visit to church comes around every week all the old favorites are sung by rote - the meaning and significance of each is well known from childhood and is invariant over the lifespan of your citizens.

When the time comes for the next cycle - for the old tongue to die - the hymns and standard prayers are then all sung in the next language in line.

Next in line? There are 10 cloisters kept deep in the bowels of the Capitol's citadel, each having dozens of priests - ranging in age from newly qualified novitiates to the old men charged with educatng them , passing on language. The inhabitants of each cloister are set to guard a language unique to that group - all-in-all there are ten languages - sufficient that no language will come around again within the lifetime of an individual. When the (~8 year?) cycle demands it, the novitiates pass to the parishes and lead the proceedings freeing up the old priests to return to their respective cloister and train novitiates of their own when the time comes.

As a safeguard against any enemy achieving a parallel cloister from the last cycle, each time a language comes around (~80 years) it has been deliberately altered - just a little, just enough so that when a new congregation member joins a church their recitation of the common prayer as proof of authenticity should be flawless or they get carted of to wherever spies probably don't like to go.

This system has the advantage that each change of the language in on a mnemonic hook with commonly understood meaning, the rhythm and tune helps to add variety to the sensory channels that are used to memorize the fresh words. Making the songs and prayers humorous/sexy - relevant to the lives of the people will help bring the words to life and make them easier to recall.

The main disadvantages as I see it is the upheaval as the old language is banned. The young shouldn't have too much trouble, but the old - well, who listens to them anyway.

My answer has to be a bit of a frame challenge. I'm going to try to answer it as best as I can, but there are fundamental issues with a language changing that fast in a modern society which simply prevent a straightforward answer from occurring.

You cannot have a "modern society" without a written language, much less with a language which is intentionally being corrupted at an astonishing rate. You simply have to create a different kind of society: in particular a society that has no technology whatsoever. I would assume we could still manage to create wheels, and probably an inclined plane, but certainly nothing so complicated as, say, Roman Trireme from the 7th century BC.

Technology is founded on the theory that you can learn to do something once and communicate the result to others so that they can use it without having designed it themselves. Consider the iPhone as an example. A team of very talented engineers developed all of the hardware and documented it. These documents were then sent to other engineers at Foxcon to design the hardware production lines. These engineers at Foxcon were certainly smart cookies, but I'd feel comfortable saying they aren't in the same class as the designers of the iPhone. Beneath this is a veritable army of Chinese laborers earning \$2.50/hr assembling these en masse.

This was only possible because the engineers could convey everything down the chain. This can only be feasibly done with written word. Now it could be interesting to visualize a world without a written word, which comes up with a more organic alternative to modern technology. It could be interesting to see what kind of work instructions survive the inherent mutations which occur in the games of telephone that ensue.

But there's an issue. Not only is there no written word, but you want the language to change sufficiently as to be incomprehensible every 10 years. How is that going to affect memory retention? Now I can make a /click shunbhnl pujvtwyloluzpisl yhaoly lhzpsf, if zptwsf ayhuzspalhapun aol dvykz /click...

Oh, I'm sorry. I switched tongues for a moment. If I may repeat the last sentence: "Now I can make a language incomprehensible rather easily, by simply transliteating the words." Admit it, you had no idea what I was saying. But that was nothing more than a simple Caesar Cypher with a shift of 7 characters. It made it incomprehensible to you, but takes a nation who wants to attack your language and 9th century mathematics (the Arabic mathematician Al-Kindi had documents showing how to do the frequency analysis attacks that break the Cypher), it will take all of about a day to crack this encoding. Especially if the single greatest threat to the nations is their inability to provide propaganda.

So this means your language doesn't just need to be incomprehensible. It needs to be so different that there it is not easy to make a mapping from one language to another.

You need a language shift like changing from English to Chinese. Those languages are sufficiently different that it is very difficult to get the nuances correct (I heard an anecdote of someone who got a tattoo in Chinese that said "Dog Lover." A Chinese person had to eventually politely point out that they had used the wrong characters, and what was actually written was more along the lines of "one who fornicates with animals.")

Which means I have to translate all of my important knowledge in my head every 10 years. Think about what that does to a society. Imagine someone trying to get a PhD, and knowing that their first years as an undergrad have to be translated up into the current language or be lost forever.

It just doesn't work.

So how do we make it work? Smooth gradients. Don't make the language change every 10 years for everyone. Make it change at different rates by location. Those closest to The Government have a language that doesn't change quickly. It might even have writing. May be the language changes at the rate L.Dutch pointed out which how the younger generations write text messages. As you approach the edges of the nation, have the language change faster. Maybe at the fringes the language changes every 5 years.

To change that fast, you're going to have to basically break what makes those people human. You're going to have to have attacked them at a biological level and prevented their language centers from doing their job. Perhaps you put them in situations where photographic short term memory is critical. There is the Cognative Tradeoff Hypothesis which showed that apes have astonishingly good photographic short term memory, using sections of the brain which we use for language instead. This theory is currently discredited for many reasons, but in a World Building environment, you might be able to turn a blind eye, and use this hypothesis as if it were true. Put these people in a world where survival depends on short term memory, and watch their language skills deteriorate.

The key is that the language, and the propaganda will need to propagate outward from The Government to the hills. This will create a gradient which makes it hard for propaganda to go backwards, from these language-idiots towards the central capitol. A dependence on the technology produced by The Govenment and the regions with slower-changing languages may suffice to keep them in line.

Thus, if you got propaganda to the inner regions of the nation, it would be effective and in the right language. But getting it there, via word of mouth, is like swimming upstream.

Languages generally do not change that fundamentally in 10 years.

We who are native English speakers in America still understand most of what Shakespeare wrote in England over 400 years ago (and the rest we get with a bit of training).

# Your best hope is some type of hybridization. Specifically, a creole.

A creole language, or simply creole, is a stable natural language that develops from the simplifying and mixing of different languages at a fairly sudden point in time: often, a pidgin transitioned into a full-fledged language. While the concept is similar to that of a mixed or hybrid language, a creole is often additionally defined as being highly simplified when compared to its parent languages. However, a creole is still complex enough that it has a consistent system of grammar, possesses a large stable vocabulary, and is acquired by children as their native language, all of which distinguishes a creole language from a pidgin.

Some creoles are still intelligible to a native speaker of one of the base languages. But many are not.

One example is Haitian Creole:

Haitian Creole...is a French-based creole language spoken by 10–12 million people worldwide, and the only language of most Haitians. It is a creole language based largely on 18th-century French with influences from Portuguese, Spanish, English, Taíno, and West African languages. Haitian Creole emerged from contact between French settlers and African slaves during the Atlantic slave trade in the French colony of Saint-Domingue (now Haiti). Haitians are the largest creole-speaking community in the world.

The usage of and education in Haitian Creole—which is not mutually intelligible with French—has been contentious since at least the 19th century: where some Haitians saw French as a legacy of colonialism, Creole was maligned by francophone elites as a miseducated or poor person’s French. Until the late 20th century, Haitian presidents spoke only French to their fellow citizens, and until the 2000s, all instruction at Haitian elementary schools was in French, a second language to most of the students.

Haitian Creole took about 60 years to develop, though this was during a time of an increase in the slave populations, which also came from a variety of locations, each with their own language. I don't know about doing it in 10 years, but certainly it could be a bit faster than 60, with the right conditions.

Another Creole which developed in the Americas is Gullah.

Gullah, also called Gullah-English, Sea Island Creole English, and Geechee, is a creole language spoken by the Gullah people (also called "Geechees" within the community), an African-American population living in coastal regions of South Carolina and Georgia (including urban Charleston and Savannah), as well as northeasternmost Florida and the extreme southeast of North Carolina. Closely related varieties are spoken in the Bahamas, namely Bahamian Creole. The Gullah language is based on different varieties of English and languages of West and Central Africa.

Gullah resembles other English-based creole languages spoken in West Africa and the Caribbean Basin. These include the Krio language of Sierra Leone, Jamaican Patois, Bajan Creole, Trinidadian Creole, Tobagonian Creole, Guyanese Creole, and Belizean Kriol. It is speculated that these languages use English as a lexifier (i.e., their vocabularies are derived largely from English), and that their syntax (sentence structure) is strongly influenced by African languages...

Gullah is most closely related to Afro-Seminole Creole, spoken in scattered Black Seminole communities in Oklahoma, Texas, and Northern Mexico.... There is debate amongst linguists concerning the relationship between Gullah and African-American English (AAE). There are some that postulate a Gullah-like "plantation creole" as having been the origin of AAE. Others cite different British dialects of English as having had greater influence on the structure of AAE.

# So, how do you create a creole?

You do this by bringing together two or more sets of people who only speak one language (or sets of non-overlapping languages) and force them to interact.

Your governments might do this by keeping people apart then mixing them in specific ways, requiring them to work together daily for those 10 years, without interpreters.

This can't work forever, as eventually the creoles will start to resemble each other, unless you bring in outside linguistic groups. But bringing in outsiders is what led to this mishegoss in the first place.

Your best bet is simply to stop migration. In and out. A la North Korea. This doesn't fit your premise, but it's a lot more realistic.

I am afraid that 10 years is to short a time to mutate a language beyond comprehension. People who grow up in a linguistic environment are pretty much set in their ways when they leave their teens. This is the reason that older generations end up sounding archaic to their grand children. Change through mutation takes at least a full generation.

Another problem with mutating a language quickly, is that without a central reference the mutations will lead to fragmentation of the language. Not only will other nations not understand the language, speakers from different regions within the country will also have a hard time understanding each other.

So rather than changing the language through gradual mutation, you would need to introduce a new language and forbid the use of the old. This has been done many times throughout history and is most certainly doable in ten years time. All human beings are able to learn a new language in a few years time. Older people will not be able to speak a new language perfectly, but they will be able to communicate with an accent.

Since there is no written media, the education would have to be carried out through compulsory classes headed by some kind of government officials. These might be clergy, military or some other kind of civil servants. Stiff sentences for using the old language would have to be administered and benefits for speaking the new language perfectly would also be needed. The classical method would be to only accept people speaking the new language perfectly into public service (military, clergy etc.).

The situation you describe actually offers a unique reason for people to switch language. Anyone not switching to the new language would become a traitor to the nation and would be aiding the enemy. In times of conflict, this would be a huge incentive.

• Introducing a new language and forbidding the old is certainly doable on a ten-year timescale. Actually eliminating the use of the old language isn't: look at the Australian, or the American, or the Canadian effort to "civilize" the natives by forcing the use of English. For that matter, use of the old language can become a symbol of resistance against the government: look at the Russian effort to exterminate various eastern European languages, or the English effort to exterminate Welsh. – Mark May 9 at 19:40
• Except in the cases you cite, it was forcing a subpopulation to learn the language of the majority. It was not to change the language of the majority. Oh, and incidentally, in the case of Canada, it didn't work. – Keith Morrison May 20 at 8:35

Name people after common objects, then stop using those words when they die.

Exactly this practice is described in Frazer's The Golden Bough:

Further, when the name of the deceased happens to be that of some common object, such as an animal, or plant, or fire, or water, it is sometimes considered necessary to drop that word in ordinary speech and replace it by another. A custom of this sort, it is plain, may easily be a potent agent of change in language; for where it prevails to any considerable extent many words must constantly become obsolete and new ones spring up.

[...]

In the seven years that Dobrizhoffer spent among these Indians the native word for jaguar was changed thrice, and the words for crocodile, thorn, and the slaughter of cattle underwent similar though less varied vicissitudes. As a result of this habit, the vocabularies of the missionaries teemed with erasures, old words having constantly to be struck out as obsolete and new ones inserted in their place.

Requires a culture shift, but if you can convince people to strenuously avoid taboo words, or words that sound like taboo words, or replacements for taboo words that have been used so often that they themselves become taboo, you can end up with fairly rapid language change.

This isn't just theoretical; the Dyirbal (pronounced like "gerbil") language spoken by a subgroup of Australian Aboriginals actually demonstrated this to linguists; they visited the community twice, a generation apart, and many of the observations from the first visit were unusable by the second visit, as too much of the language had changed. NativLang did an interesting video and follow up about it exploring how the rate of language change varies based on different factors.

You do realize that given your proposal, you're making it easier for spies?

I live in a multilingual community and it's entirely common for people who can't think of the correct word in one language to switch to another for that word, even if the two people conversing are using the same language in the conversation. It happens so often that people don't often realize they're doing it.

Your premise is forcing the entire population to be multilingual, so that will be going on all the time. It will be so common, and necessary, especially if the languages are as unrelated as you're trying to make them be, that people won't think it odd at all if they come across someone who is struggling with the language; after all, odds are they have done it as well.

Forget about in-depth training to learn the right accents, phrasing, grammer, and idioms to try and blend in. There's no need for it. "You can speak the current language well enough to get by? Good. We're sending you in when the idiots are switching again. Don't worry about getting it right, their whole population is going to be in the exact same boat."

• Yes. Indeed. This. – Cyn May 13 at 14:20

Clearly, there are two languages. One is used in daily interactions by regular people. Nobody cares if a foreigner overhears their dinner plans. Well, maybe targets of assassination.

The second language is used in official correspondences within the government. To protect official correspondences from being translated, they are protected by a cipher. Welcome to cryptography. Your problem is now encryption key storage and transmission. Today's cipher key is 13. Tbg vg? Mistakes in key transmission and storage become plot points. Good luck making the story not a comedy.

Without writing, the complexity of ciphers available is limited by the mental abilities of government officials. Either it's part of the exam to become a government official and people study for years to master mental encryption with changing keys, or the government ends up with a series of languages that sound like igpay atinlay.

Be careful with the delayed propagation of keys due to the size of the empire. Someone might accept orders encoded with an old key. Loose infosec sinks death stars.

• A very practical solution, but I feel it side-steps my question a little. The question is about the rapid change of language, not concealing information. – A Lambent Eye May 9 at 8:23
• Please clarify the question to explain why this solution is not acceptable. You make a big request that I think requires creative solutions. Also, concealing information is the domain of techniques like steganography. Encryption transforms information to a form that makes it unintelligible even when it is broadcast. – Lofty Withers May 9 at 8:46
• While entirely correct, my question is explicitly about how to evolve a language quickly. Your answer, which I interpret as "Have two languages, one of which is obfuscated in one way or another." does not answer this question, but creates an alternative scenario in which the question needn't have occured. On a different note, I wrote 'concealing information' with the intent to mean "not having information clearly legible" and not as in 'hiding', and am sorry for any confusion this may have created. – A Lambent Eye May 9 at 10:17

If you get a sore throat and stuffed nose, your ability to correctly pronounce and speak the language is significantly reduced. Yet you can still be understood by most. Now this normally won't change the language, because people usually get better. What if they didn't?

What would happen if most of the population got a stuffed nose that lasted for a couple years?

Over time, the language would adapt to the new way of pronouncing the words. You might even get new words that are more comfortable to say given the current condition, and it might not revert back if the conditions improve. If the population developed a sore throat after having a stuffed nose for 3 years, the language would mutate further.

The changes probably don't have to be significant, but cumulatively from lasting for a long while and having different combinations (sore throat, numb tongue, swollen jaw, stuffed nose, etc), the language should mutate appropriately to be unrecognizable over a decade.

You could have this be a natural thing, as a result of large scale climate cycles, virus, phenotypes, mutations and/or whatnot. If you need it to be controlled by the government, you can get a neat conspiracy thing going.

• Many years ago, it took me several years to figure out I was allergic to dairy. I had a chronic stuffy nose and chest for years. In no case was my chronic condition an impediment to communication. When I finally stopped all dairy, I found I had to relearn how to make nasals (these are consonants that resonate through the nasal passages, like "m" and "n" and "ng"). It only took a few days. At most, your sickie population might blur the distinctions between nasals and non-nasals, but it would not create an unintelligible language change. – Cyn May 9 at 17:30
• @Cyn You're an individual though, unless you're a very influential person, your impact on the language is minuscule at best... However, why and how did you relearn how to make the nasals? I assume, because everyone else still used it, and it was still the correct pronunciation of the relevant words. As such you had references on what it was supposed to sound like, and which words it was used in. If you didn't, and nobody else used it anymore, why and how would you start to relearn it? – Spoki0 May 10 at 7:34
• If everyone was stuffed up for a couple of years, the nasals would come back IMHO when that mass illness was over. Even if they didn't though, it wouldn't make that much difference in the language. It's still completely intelligible to someone who left town before the mass illness and never got it, then returned when the illness lifted. – Cyn May 10 at 13:57
• @Cyn accents don't revert by themselves, so why would a very nasal accent do, just because it's caused by an illness? I never suggested stuffed nose by itself would be enough, but over a 10 year period, and with a combination of different issues lasting for a year or two. – Spoki0 May 11 at 14:26
• You mean a non-nasal accent. Sure, it could turn into a regional accent variation. But 10 years is not long enough for linguistic drift to the point of creating a mutually unintelligible dialect. Even Americans and Brits, with 500 years of separation, have no trouble understanding each other 99% of the time due to accent (lexicon differences account for most of the problem). Granted, there are some British accents even other Brits have trouble with, but we're still talking a very long period of change and they can all speak so others can understand if they choose to. – Cyn May 11 at 17:08

## The Best You Can Do

### Put Children in Creches

If all kids are removed from their parents and placed in a controlled environment from early childhood, they can be taught whatever conlang the government wants.

It doesn’t get you a situation where people switch to new languages at age fifty, sixty and seventy, but it might get you a situation in which a thirty-year-old who hasn’t lived there in a dozen years wouldn’t understand teenagers.

This still isn’t exactly what you’re looking for, but that’s not realistically plausible.

• This will get generational changes in language, not the decadal ones the OP wants, and in practice, will just mean everyone knows all the languages. – Mark May 9 at 19:44
• @Mark That’s what I said. It’s the closest we could realistically come, though. It does result in the native language of each cohort being different, so a thirty-year-old who hadn’t lived there in a decade wouldn’t understand teenagers. – Davislor May 9 at 19:49

Let me quote a comment from the user barbecue:

I think there are too many flawed assumptions in this question: The idea that you can have a language which is both secret and commonly known; the idea that you must train teams of translators rather than simply grabbing native speakers off the street and forcing them to help you; having modern technology without written language; being able to prevent people from learning languages other than their own.

To satisfy that seemly contradicting assumptions, we need to think outside the box and find some extraordinary outlier. So here goes my idea:

1. Every newborn baby is submitted to a mandatory brain surgery as soon as he/she is delivered.

2. In the surgery, a device responsible for communication is implanted in the baby brain.

3. The device connects the person brain to the internet through Wi-fi/radio/cellphones/bluetooth/whatever.

4. People speaks to other people through the device implanted into their brains.

5. The device employs asymetric strong criptography in the transmitted data.

6. The government runs the central certification authority responsible for issueing digital certificates that enables the data transmission be possible.

7. Digital certificates have a lifetime shorter than 10 years. People need to renew their certificates on occasion before they are expired.

8. Brain devices refuses invalid, expired or revoked certificates.

9. The device is based in very complex and miniaturized nanotechnology featuring a lot of built-in layers of protection and criptography. Hacking or counterfeiting the device would require a billionaire investment and some years of complex research which only a very determined and rich state-sponsored agency could hopefully afford. There is simply no way that it could be hacked or counterfeited by average Joe in a garage.

10. Nobody else speaks or writes a single word in this country anymore. Whoever insists in doing that will be submitted to a brain surgery to forcedfully be made unable to do that again.

11. Eventually, spoken and written language will be forgotten. Those are deemed as too obsolete, slow, primitive and unnecessary. Everybody will communicate through their brain devices and there would be no need to speak or write anything anymore.

12. Unwanted people will have their certificates revoked by the government, which makes them unable to effectively communicate to anybody else. People trying to hack brain devices and people considered as traitors are some of those considered unwanted.

13. Everyone who leaved the country for some years would be unable to communicate with anyone else when he/she returns.

14. The government actively snifs and records the communication of its citizens looking for suspicious people doing suspicious stuff.

15. All the written language is replaced by a QR-code-like language which don't make any sense for people without a brain device.

If you want the language to actually become incomprehensible, the language evolution cannot be natural. We don't want small changes in every word (e.g. a change of a vocal, a syllable omitted etc), we need to completely replace the word. And we have to do that nation-wide. Solution:

Autohypnosis programmes in TV

Every day people have to watch a TV program when they get a list of words and their new replacements, e.g.

cat -> malgo


The new word should be generated randomly from a list of syllables.

Then every person has to go through an autohypnosis session and replace the old words in their memory with the new words. If they miss a day of the programme, they can rewatch it later, they will still be able to understand most things.

If you replace 10 words every day, in 10 years you can replace about 35.000 words (commonly used words should be replaced at least once a year). The active vocabulary for most people is only about 5.000 words.

A person who is not watching autohypnosis programmes won't be able to understand a conversation in a year.

The problem

This won't stop spies. There will be always some people who will also know another language, otherwise trade and diplomacy cannot work. Some people might create a new artificial language altogether to escape the constant change (sign language? Esperanto-like language? a dead Latin-like language?). You don't need a spy to learn the constantly changing language, you only need a traitor that is able to communicate somehow with foreign spies.

Don't mutate whole language, just enough (hundred?) common words which if used by a spy, will identify the spy as using obsolete version of language.

This will require whole population be dedicated in protecting the new version of the language. So ie traders talking with neighboring nations would have to be trustworthy enough to use old(er) version of language, presumably disclosed to neighbors.

For new words, use something like https://en.wikipedia.org/wiki/Rhyming_slang - used by criminals to separate "in-group" (the criminals) from the remainder of the population.

New version of the words will be learned in church hymns, as suggested by Hoyle's ghost.

• You'e under arrest for being a traitor, citizen. How do I know? In the first sentence you didn't correctly say "Don't mutate the whole language, just enough (hundred?) common words which if used by a spy, will identify the spy as using an obsolete version of the language." Okay, I kid, but the point stands. If you're depending on fast changes in the language to identify spies, roughly 95+% of the population will end up in your prisons because such errors will be even more common than they are if the language isn't forced to change. – Keith Morrison May 11 at 18:00
• @KeithMorrison - English is my third language, and and articles are killing me, so I am guilty in that. Also, it is OP's problem with mutating the language too quickly, I just proposed a mechanism for that (the rhyming slang). And arresting old-speakers is also included in accepted answer. – Peter M. May 13 at 14:40

Using computers, this should be possible. So we assume the government mandates every office to be paper free and no-one is allowed to keep important documents at home.

Books are replaced with e-readers, disks with cloud services, and so on.

The computer networks themselves are hardened through encryption. I assume this part works well - no reason why not. There may even be some measures built-in to keep them from working outside a given area, by measuring time delays and other stuff.

Even game makers have to update their software, and players who don't learn fast enough or make mistakes only non-natives would make get kicked out. Businesses and administrations even more so.

The changes to the language build on features typical to the own language which are also difficult for the people of other countries to pronounce, or to learn - sounds, sound combinations, grammar and so on. Every day, some small change gets propagated through the media, all laws and other often used texts are updated accordingly. Some of the changes are not propagated, but get introduced quietly - especially where a native speaker will catch on easily and a non-native not so easily.

Also, the use of references instead of talking plainly is encouraged. This way, only someone with access to the network and/or inside knowledge can understand a document.

New grammar rules are introduced which are basically encryption systems - so that words change their meanings depending on context of all kind, so that a sentence sounds like gibberish to anyone who grew up with the other languages, and so on.

Words which people in other languages may censor themselves are also used - like curse words, names of respected/historical people, names of gods, and so on.

Also words which have another meaning in other languages so their speakers trip up, and such.

People working in sensitive areas get concentrated into different places. They will be taught some specialised vocabulary and grammar, some of it even confusing to natives. Some of it easy to track so leaks can easily be found. Dynamic internet content makes sure people have their own accent, which is used as a finger print. New ideas are sometimes tried in this, sometimes in that area.

Sometimes, very large changes are pushed through, and people are sent to schools to learn them. Schools also exist for the people slow to pick up on the changes. The ones who stay too slow have to live in places where and work jobs in which no information of any value is released. The schools have a lot of "students" whose main duty is to find anyone who is not a native.

With other countries doing the same, people are employed to find ways to keep up with their developments, and the results are not only used for spying, but also to make it more difficult for the others to keep track.

Ideally, any differences in physiology, mentality, abilities and so on are also used to increase the distance to the other countries, and furthered through reproductive medicine and such - only the people who have the correct characteristics can become sperm or egg donors, get into jobs where people are more likely to multiply and so on.

Mutations which help pronounce unusual words, understand unusual grammar or such are actively searched and spread through the population in similar ways.

There is some pidgin based on older language to get trade agreements and such. The trade itself is done without talking at special sections of the border. Otherwise, the borders are closed.