# Why would a telepathic species use spoken language? [duplicate]

I'm currently designing an advanced alien civilization that has achieved telepathy. The idea is that each one of their species has a small device merged with their brain that can allow them to communicate with multiple other ones of their kind at the same time, no matter how far away they are from each other.

However, the species I'm designing also has a spoken and written language, and there's where the problem begins. If a species has telepathic technology and it's a far better way of communication, then why would they still keep their spoken language?

I've been trying to came up with a reasonable answer but I couldn't came up with something good. So my question is, why would a telepathic species still use spoken and written language?

Edit: I'm making a few edits just so everyone knows. Their species has left behind their natural bodies for biomechanical ones that are powered by an infinite energy source, so the telepatchic devise doesn't draw too much power from their bodies. Also their society is pretty utopic, they don't have some higher goverment leader, they don't have crime and they don't have privacy. Basically there is no need to keep secrets from others. And lastly, the telepathic device is actually part of their biomechanical bodies, so they're sort of born with it.

• Could be for historic reasons, especially if this species is not biologically telepatic, but uses a tech for that. They could know other species which do not use the tech and they need to communicate with them. Maybe the kids have to learn a spoken language to learn enough to use the tech for telepatic communication. – Julian Egner Nov 30 '18 at 8:31
• @ΓΙΑΝΝΗΣ ΜΙΧΑΗΛΙΔΗΣ - Welcome! We need to know much more. Can you spy on someone's thoughts? Can you block someone you don't like (exes who are stalking you)? Can you have conference calls? I think issues like this have to be explained before we can answer properly. It might be best to put your question on hold while you add these things to your question. ;-) – chasly - supports Monica Nov 30 '18 at 9:32
• The Belcerebons lived on Kakrafoon Kappa and caused jealousy among their neighbouring civilisations by being enlightened, calm and quiet, behaviour judged to be smug and self-righteous. The Galactic Tribunal as punishment forced telepathy upon the Belcerebons, so that they now must talk continuously in order that their every thought is not broadcast. Restaurant at the end of the Universe. – Spratty Nov 30 '18 at 11:47
• Are their TVs also telepathic? – Xavon_Wrentaile Nov 30 '18 at 23:09
• When you say they don't have privacy, how do they filter important information? And how does the "signal" work? Is every member receiving a constant, continuous blast of information (I'm imagining a noisy sports bar with multiple televisions each on a different channel but in my head)? Or is it more directed, and you have to give your intended partner a mental tap on the shoulder? Also, how are their memories? Can they remember every thought? – miltonaut Dec 1 '18 at 0:39

The tone of the voice covers an estimated of 38-40% of our communication (depending on research), this is a common problem sending E-Mails in corporation since the mind and state of the receiver compensate with their own state and voice, given that a friendly E-mail sent to a person in an less than optimal state can receive it the wrong way.

I would assume that the device in the brain only relays information but not the tone of the voice, the passion, the care and warmth. And by that loss removing 38 ish percentages of the communication.

Scenario: One of your loved ones got hurt, died etc. You got dumped. Displaying affection:

Would you like to get that information in a text message on your phone or do you want to recieve it from a person with care and warmth in their voice? Sure "you got a meeting at 5 on floor 22" could be delivered by telepathy, but the words "I love you" would need the personal touch of a person so you know they care.

• I like the inversion of the usual 'telepaths can convey more than words' trope. That's a nice touch. – Joe Bloggs Nov 30 '18 at 11:32
• I thought so too, but since it was an implant, i thought it would loose some personal touch, and since it wasn't specified i took the liberty. – Magic-Mouse Nov 30 '18 at 13:39
• Where do you receive the information warmth cannot be transferred telepaticly? Maybe you could even transfer more emotion, warmth and feeling as it would be possible with words? just sayin' . Wouldn't it also remove mostly all of our missunderstandings? It happens very often sth sarcastic from me is considered as offense. – user55267 Nov 30 '18 at 14:51
• @Jannis That information isn't in the question. It's given as the solution to the problem the question presents. Question: "How do I keep voice relevant?" Answer: "Don't give telepathy all the same capabilities." – Fund Monica's Lawsuit Nov 30 '18 at 17:51
• @Jannis I think you might have misread my comment as just the first sentence. Try reading the whole thing. All of it, this time. – Fund Monica's Lawsuit Nov 30 '18 at 19:23

To communicate information which is not personal or individual.

The businesses and organisations in this world don't want to employ someone to constantly communicate telepathically that you should 'push' rather than 'pull' the door to enter the building. The same goes for prices of items one may wish to purchase; advertising communications; media communications such as entertainment and news; business hours signs; 'floor slippery when wet' notices; and similar general communications.

• This is a good general reason! It covers everything from the signs/postings (that you mentioned) to public transmissions like television. – miltonaut Dec 1 '18 at 0:30

The fact that your aliens need to build a device proves that they do not possess a natural inborn ability for telepathy without technical support. Therefore, in their whole evolutionary development and before technically advancing for enough to develop such device they had to communicate by means of speech and writing. This makes speaking and writing the natural form of communication of the species which they should feel comfortable with, as @Jannis already mentioned.

Look at humans nowadays! We already have small device (not yet implanted in the heads of people) which allow one or more individual to communicate with one or more other individuals as long as they have the technology and 'speak' a common language. Even though a lot of communication is handled without directly meeting and speaking to one another, we still enjoy meeting small groups of our friends and family and just talking to each other.

So this leads to the actually relevant part of your question: in order for this to work your aliens need the speak/write/think in a single language known to every individual of their species. As soon as they have such a 'lingua franca' communication via means of speech, technology, reading and writing is just a matter of personal preference and circumstances.

No matter how trained they are using the device, they still have to communicate with the untrained ones (mainly children) who have not mastered the device.

They still have to read books, reports, etc ..

Make documentaries, e.g. films, recordings, documentary programs, etc, music

They communicate via language, even if telepatically. Meaning, thoughts are expressed in words and not internal "brain code" (the brain's equivalent of computer assembly code)

• You can add to this the usefulness of written language in signs (e.g. street signs etc.) and when interacting with computers. Also, it's likely that their children (assuming they don't breed by division etc.) still need to acquire language in the usual way (by exposure to adults speaking the language etc.) - even more so if they arn't implanted at birth. – G0BLiN Dec 2 '18 at 11:26
• People teach children how to speak by speaking to them; why wouldn't telepaths teach their children to communicate telepathically by communicating with them telepathically?  (The existence of records, and the on-going need to preserve information, is a good answer.) – Peregrine Rook Dec 3 '18 at 4:10
• @Peregrine Rook, The premise of the question as I understood it, is that two people must have telepathic capabilities to communicate. Otherwise, it's like having a phone, and attempting to contact someone who does not have one. – Christmas Snow Dec 3 '18 at 9:05

and it's a far better way of communication,

Until the advertisers are in your brain every second of every minute of every hour of every day of every month of every year FOR YOUR WHOLE DAMNED LIFE. (As usual, Futurama has something to say about it... https://www.youtube.com/watch?v=CvqYmrSjXv4)

And you have no secrets from anyone. Ever.

So... no. It's a horrible method of communication.

then why would they still keep their spoken language. I've been trying to came up with a reasonable answer but I couldn't came up with something good. So my question is, why would a telepatchic[sic] species still use spoken and written language?

• Density: you can read a lot faster than you can listen
• Permanence: thoughts are evanescent. Video and the written word will be around a lot longer.
• Privacy: you don't want everyone knowing your thoughts.

But, you say, there are controls on who you let read your mind!! LOL no. The government will think of some justification for giving itself the right to listen in. And, if you're a minor, your parents will definitely be given the right to read your mind. (It sure would have been helpful when raising my kids!!)

• In addition to the 3 excellent reasons given above: intimacy: when you want a more personal touch than that of an Email. inanimate objects: maybe you don't want telepathic intrusions from a door sign or a computer. recreation: live music or a good film don't translate well to telepathic messages. etiquette: just as it's impolite for humans to start texting in a social context, it's rude not to use your voice in the company of friends and colleagues - even more so if they aren't implanted (too young, different species, medical/religious/lifestyle reasons etc.) – G0BLiN Dec 2 '18 at 11:36
• This answer seems to imply that it is possible to switch the device off. Please add that assumption to your answer. – user3106 Dec 3 '18 at 15:45
• BTW I disagree with your first bullet point. The comparison is not between reading and listening, it is about speaking/listening versus communicating thoughts. The latter is probably much faster (e.g. no sensory processing required). – user3106 Dec 3 '18 at 15:46

## Disclaimer: May cause Fatigue

"The TeleTransmitor3000© runs on the energy available in your body, specifically your brains energy. Sending information will use up some of that energy and beginning users might experience some fatique after prolonged usage. It is recommended to use regular communication for short distance interactions to preserve energy."

- From the manual, page 17

• I like it! An excellent technical drawback. – chasly - supports Monica Nov 30 '18 at 13:45
• In the event that you overuse the TeleTransmitor3000©, it is recommended you eat sugar-cubes to restore your body's energy. If you are diabetic... see your doctor. – Tezra Nov 30 '18 at 19:02
• Didn't the last firmware upgrade allow hosts--I mean users--to recharge the TT3k through regular, structured social interactions? – Toddles McBerry Dec 2 '18 at 4:28
• @ToddlesMcBerry that did only apply to Extroverts, introverts are suggested to lock them selves in a dark room with a book! – Magic-Mouse Dec 3 '18 at 9:32
• Haha "Unpredictable behaviour may occur when the user is under the influence of substances" – Martijn Dec 3 '18 at 10:01

Secrecy

When you communicate telepathically, it's possible for a government agency to spy on the conversation. All the devices are required to have a special backdoor code for the benefit of this agency. These are checked regularly and everywhere you go you pass by government scanners that check the devices are working. Of course it's quite possible that hackers have broken this code - an even worse situation.

To communicate in secret you either switch the device off or if that's not possible, have a blocking device. Then you talk.

When you want an old fashioned secret conversation, perhaps with a loved one or perhaps with a co-conspirator, you naturally revert to old-fashioned speech. Children learn it because until their brains are mature enough, placing a device in them would cause real problems.

Teenagers would definitely not want their parents to know what they were thinking. I'm sure there's an app available for that and the parents might insist that the teenagers have a permanent connection for their parents' use until they reached the age of majority.

There are other possibilities. It all depends on things like the following:

Can you spy on someone's thoughts? Can you block someone you don't like (exes who are stalking you)? Can you block everyone? Can you have conference calls?, etc. How precisely does the network operate - is it like a chatroom? A single phone line?

• I think we were working on the same answer at the same time... – RonJohn Nov 30 '18 at 9:53

Telepathic communication is about as intimate as dancing the Tango.

It's great with a great person. It's not so great with a person who isn't.

• This reads more like a witty comment than an actual answer, doesn't it? Or could you take the time to expand it..? – clem steredenn Nov 30 '18 at 13:56
• This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review – Magic-Mouse Nov 30 '18 at 14:00
• @bilbo_pingouin I'm not sure how to expand on this answer? If someone asked "Why doesn't everyone walk around naked in a warm climate, when it's so much cheaper not to need clothes?" couldn't an answer be: "Because most people don't appreciate everyone seeing their private parts." ? – Patrick Huizinga Nov 30 '18 at 14:24
• @Magic-Mouse It's definately not a critique or clarification request. Not sure what gave you that idea? – Patrick Huizinga Nov 30 '18 at 14:25
• But if they have no sense of privacy, why do they care about talking to someone who isn't great or they don't know well? Are you saying they can hear the thoughts of others even when not trying to send their thoughts to the other person they are communicating with? – John Locke Nov 30 '18 at 14:53

Intimacy - telepathy is something you do with strangers and acquaintances or with people you are not physically near to.

With close friends and family though in a similar way to how people enjoy physical contact the use of spoken language is a good way to signpost how close you are to each other.

• Or maybe vice-versa? – Peregrine Rook Dec 3 '18 at 4:13

Most people are not clear thinkers. If you think some people are confusing when they try to tell what they are thinking, just imagine how it would be if telepathy transferred those thoughts immediately.

Telepathy is amazingly efficient when the sender is clear on what they want to convey. It's also amazingly confusing if they're not.

So they can keep a record of things. telepathy will only work when you are alive but for the information to sustain there is a need for a common language that can be stored in a medium that is accessible by anyone like we have books. So for common communication they use telepathy but to store & share data they have a common language. so even if they don't speak, they still need to read. Also, telepathic interface without a common language will only convey emotions and thoughts but to convey accurate facts and figures, any civilization would need a language.

That can sound trivial, but maybe for art ?

I mean, telepathic music is maybe not that awesome, as well as movies. Also, are microphones able to capture telepathic "voice" ? If not, I guess that's a decent reason.

• The mind boogies. It's bad enough now but imagine telepathic Christmas music being beamed into your head continuously wherever you go. – chasly - supports Monica Nov 30 '18 at 13:44
• Art was my very first thought. I mean, we have photography, and yet we still paint portraits, landscapes... We have recordings, but people still go to live gigs. – T.J. Crowder Dec 3 '18 at 14:59

Technological telepathy is only good if you have broadband. Sound takes less bandwidth.

Thougths are a broadast; if you want privacy you have to speak.

Also telepathy is for now, voice messages are for later. Same reason why people send voice messages in Whatsapp. If my wife wants me to bring bread home on the way back from qork, she sends a message that I can read in the bus; if she calls me I might not pick up because I'm busy posting in World Building, and also I could forget. With a saved message I have a permanent reminder to bring bread or else.

Finally, they may have to talk to other races.

Since you say no range limits that implies it's a realtime link. Thus the answer is obvious: It can't be stored. Spoken words can be.

A Spoken Language Defines Your Thoughts

When you're thinking inside your head, you think in your spoken language, do you not? You don't think in pictures or symbols or feelings - you think in your language. You don't visualize a carton of eggs, you say inside your mind "I need to stop by the store on the way home from work and get a carton of eggs." You tell yourself things in your mind in an internal spoken voice.

Without knowing a spoken language, a telepath would simply transmit a picture of eggs and a feeling of hunger. That could mean a wide variety of things. It could mean you like eggs, you want eggs, you're hungry for eggs, you were hungry for eggs, you just ate eggs, etc. It would be confusing without any spoken context.

A real world example. Japanese people have a difficult time telling the difference between green and blue, because their language doesn't make any distinction between green and blue. They could look at blue or green and use the same word. And they have a hard time telling them apart - because their spoken language doesn't allow for the difference. If you're Japanese, they are basically the same thing. Native English speakers don't do this because we have a well defined linguistic definition of both green and blue.

The link between language and cognition is a deep one. They appear to be deeply intertwined. Perhaps telepathy wouldn't work at all without something linguistic to transmit and receive.

I'm sry for my unstructured thoughts, feel free to edit :)
A telepatihc device has to be built without telepathics. Also the devices might need training to not spam any toughts or create a hive.
Thats why you could have a spoken language for simplicity.
The written won't go away, it could only a telepathic memo be invented, but writing things down makes you remebmer things better and is easier to interact.
Also humanity wants to stay grounded and don't want to be crippled if the tools are missing. They might even like to hear each others voice.

• telepathy is something that arrives developmentally late, i.e. 'children's language' is spoken. Same way with humans -- most people don't read before age 6
• the 'telepathy radio' relies on a trace mineral in the environment that is unavailable in lean times. Or telepathy requires lots of glucose (or whatever vitamin or nutrient or calorie source)
• network congestion
• range -- telepathy is short-range like bluetooth, voice works over longer distances, like talking drums in africa or whistle/bird language in turkey
• language concerns. no reason to assume that telepathy is the lingua franca. Perhaps telepathic 'lexicons' are highly diverse, or perhaps compressed and rely on a pre-shared dictionary. Spoken language is more likely to be in common.
• security -- perhaps telepathy is dangerous like running a program, and speech is less likely to convince you of something or steal information from you
• multitasking -- telepathy takes a lot of concentration like using your phone screen and temporarily shuts down visual attention; voice is 'hands free'. Don't text & drive

This is a supplement to the answer by Jules R. Since very little in the way of work would be needed by such a society, almost everyone will need to find other ways to pass the time. There may also be a strongly felt need to stay "grounded" by remembering the old ways.

Art forms that use written or spoken language (plays, music, paintings, sculpture, etcetera) will still be used from time to time. Anachronists will do re-enactments including creating illuminated manuscripts, court documents and the like. Think pioneer villages and war re-enactments.

Telepathy might not be practical for communication across certain distance ranges, such as geosynchronous orbit.

In analog computers, the components of a thought have characteristic "dwell times". For human brains, this is a multiple (or fraction) of 150 milliseconds. This "dwell time" is convenient for fundamental biological activities like heart pacemaking. If an echo of a thought occurs with the wrong time delay, this can make it much harder to think. This phenomenon is known to occur with human parsing of speech that has been subjected to time delays in this time range. Suppose that this species had a similar "dwell time" when it was purely biological.

Suppose that during the transition from biological bodies to electromechanical bodies, the species chose to maintain compatibility with biological thinking speeds. Then the electromechanical bodies would still have a thought "dwell time" of about 150 milliseconds.

150 milliseconds is 45,000 kilometers at the speed of light. This is longer than the straight-line distance between any points on an Earth-like planet, but shorter than many distances involving geosynchronous orbit.

This means that the species would be able to telepathically communicate anywhere on the planet, but would have trouble telepathically communicating with individuals in geosynchronous orbit. It also would create an evolutionary barrier to evolving shorter dwell times: increasing the thinking speed would interfere with the ability to telepathically communicate with individuals elsewhere on the planet.

It is very interesting to think of how a telepathic species would develop a means of communicating complex ideas without the use of a spoken language. Thought is generally distinct from the way in which it is expressed, even unto the thinker. It, by itself, does not have sound or imagery or even emotion. These are things that our brain puts on top of existing thought to make them more workable and useful, so something like language is invaluable to be able to not only communicate but even think about complex tasks.

One great example of this is the Protoss from the Starcraft universe. This is a species of telepathic aliens who do not have mouths. There societies were very primitive for a very long period of time, then someone discovered written language and their society became much more advanced. It took that element of language to elevate them beyond savage cultures and technology, even though they could all perfectly understand the basic concepts they were able to relate to each other through their telepathy.

In short, a formalized language, facilitated through a writing, goes a long way towards complex thinking required of advanced (or even non-primitive) societal, cultural, and technological progress.

The author Iain M. Banks covered a technology with similar capabilities in several of his Culture novels. The members of The Culture society use a device called a Neural Net to connect them to an all-pervasive, completely open internet. As such, they are perfectly capable of communicating in the manner the OP is describing, i.e with technological enhancement as well as access any file or broadcast they choose.

## Breakdown

• Whilst they do have organic bodies, bio-mechanical enhancement is common place, and each individual has the Neural Net implanted from an early age (if they wish) so that it grows into and with their organic brains.

• In several of the novels we encounter characters that reject the use of the Neural Net for all communication and eschew technology as much as is practicable in their society (The Culture is hyper advanced and post-scarcity - tech is ubiquitous).

• It is also a common theme throughout several novels (most notably explored in Excession) that the inside of a persons head (be they AI or not) is inviolable without consent, and even then is generally seen as taboo.

The above suggests that in a society where telepathic communication is not only available but regularly used, verbal communication would have a number of uses, most importantly maintaining the privacy of ones own thoughts. There also may be resistance to using the technology from factions within your society for reasons of over-reliance, secrecy, or a general mistrust; much as our own society responds to social media and telecommunications.

TL;DR: Banks' Culture novels are a good demonstration of how telepathic communication might be used in a technologically advanced society developed bio-mechanical, telepathic enhancement, and I would strongly recommend The Culture novels for some research into the topic.

Most communication is superficial and filled with white lies. With telepathic communication you can't fake your real feelings.

Most people rather hear the spoken white lies than get the telepathic truth.

# Telepathy is like a cell phone

Telepathy basically sounds like a cell phone built into each person's suit. You can turn it on and call someone over a long distance, or connect to group calls and talk to lots of people over a long distance.

So let telepathy have the same drawbacks as the cell phone. You need to know the persons number to call them! If you have people you routinely talk to, then you can talk to them clearly, at any distance. On the other hand, if you meet someone on the street, you would need to attune your 'thought speech' emitters to some 'frequency' that you can 'dial' them at.

You have to ask them their number before you can call them on your 'thought speech' device. How are you going to ask them? Spoken language.

# Written language is a different use case

Written language is basically a whole different use case. This is for storing information long term. The way we store information long term (writing) is quite distinct from the way we communicate face to face (speech).

There is no reason for something that mostly replaces speech to also replace writing, since that is a whole different use case. A 'telepathy book' is like a podcast, and podcasts have not replaced books, or written language.

It depends on the mechanism of telepathy. If your race has the possibility for people to be "thoughtblind," that is, unable to perceive the thoughts of others, then some kind of spoken language will be necessary. Also, thoughts have shades of meaning that are very difficult to interpret objectively, so your legal and scientific communities would need some sort of language to communicate without the possibility for misinterpretation.

I'm actually working on a race like this, myself, and they do have a spoken language, but it's not nearly as advanced as the languages of other, non-telepathic races. They've had to catch up with the way the rest of the galaxy communicates as a result of their telepathy.

With a race that has developed telepathy as a technological advancement instead of an inherent biological/evolutionary aspect, there would always be traditionalists who believe in the art of language instead of the brute force of mind-to-mind communication.

All forms of communication serve a purpose. We have spoken and written, they would have telepathic, spoken and written. Different purposes would appear.

With the data given - maybe spoken language is better if you address a room full of people - what exactly do you need to communicate to other telepathically? Maybe you need to know their name or have made a "connection" - in such case, spoken language is for speaking to a crowd or to those you don't know (yet).

Then, of course, there is recording and radio, there is acting, singing, television. All of those use spoken language and may or may not translate well into telepathic communication.

Edit: I skimmed too quickly and missed a similar answer already written by kingledion. Please note that this has a slightly different focus; it assumes that not everything in your utopia is actually perfect.

Just to add an opposing suggestion to the "telepathy is for impersonal communication, speaking is for when you care":

Perhaps it'd be more like how things are now - we generally talk to strangers without much concern, but generally only participate in long-distance communication with people we trust (to some degree, in some way - even messaging someone anonymously over the internet now only happens because people trust it won't cause themselves any consequences). I'm perfectly happy to give a stranger on the street verbal or written directions to the nearest McDonalds, but I'm not going to give them my cell number or email address to do so, no matter how efficient it'd be.

On an tangential note, it would be helpful if you fleshed out what you mean by your assertion that "there is no privacy". Depending on what you mean, telepathy and speech may be practicably indistinguishable. On the slightly flippant side, one could quite comfortably classify speech even in a non-technological world as "short-wave, non-private telepathy". My answer assumes that the lack of privacy is in comparison to most cultures, rather than being a complete deficit.

Others mentioned cell phones and email, but I'll also draw parallels to two-way radio and TTS (Text to Speech).

Since the TeleTransmitor3000© is a machine, you get all of the connectivity and perks and drawbacks that modern (to us) communications offers: instantaneous communication, ease of use, low effort to talk/transmit, requires an active network subscription, previous generations don't know how to use them well or within established norms, etc. Importantly, the TeleTransmitor3000© does not have Smell-O-Vision™®©, so olfactory data is not transmitted nor received.

Most importantly, to save money and bandwidth, the engineers decided to implement a TTS system. Therefore, the person speaking telepathically has no control over the reception of their voice. This means that you get the same low fidelity, low bandwidth, monotone, wrong syllable emphasis, voice from everyone who connects telepathically. Which kind of sounds like a robot talking on a walkie talkie. The TeleTransmitor3000© is audio-only, there are no visuals, so there is no associated body language like posture, hand and arm signals, or facial expressions to convey additional details.

Therefore, when speaking in meatspace, it's a much more pleasant conversation. The speaker has many more avenues to deliver their message:

1. The speaker and listener can see each other in real time and how they react to what was just said.
2. The speaker and listener can use appropriate touch and body language to their full effect.
3. The speaker and listener can utilize their (unique) voices, which could be further modified by upgrades like the Vocalator 9001™®© or Batman's Ear Wins.
4. The speaker and listener can take in and exude each others smell, which can be more potent with upgrades such as the Musk Enhancer 69, Aura of Aphrodite, or Raging Wolf's Nose.

I'm terrible at naming things, don't judge me!

I love this question, and hope what you’re makeing works out for you. The answer seems to be in the question. Your race has a DEVICE in their heads, and devices aren’t born into the original being. This species has evolved over a millennium,and has been speaking longer than communicating telepathically. Also, if they graduated to biochemical bodies at the same or similar time as gaining their telepathy, they might be immortal. This means that the written and spoken language would be passed down from generation to generation. If they have invented space travel to other inhabited planets, it would be helpful to be able to speak with the natives, because the native population wouldn’t be included in their hive telepathy.

Same as some would use hand signs and codes. Secrecy, and/or hostility. Also, machines may need verbally coded commands, because not so many are telepathic in nature. Also, there may be remnants of spoken languages, from when they were developing telepathic technologies. Perhaps for radio, and historical records? Perhaps the law requires the spoken word for their records, and possible changes to their system, or to verify (again, for records) that they consent, or have understood a contract?

Perhaps some computers still require security access, or radio communications for the military? Anyone screened from telepathy will need to speak, or make hand signs. Hand signs and braille might enter at some point.

The sci-fi novel Ender's Game by Orson Scott Card provides some interesting perspective on your question, since one of the principal alien races in the book, known as "buggers" or Formics, is telepathic in much the way you describe. Not only do they have telepathic communication in fact, that communication is also instantaneous regardless of distance, forming a hive mind that every member of the species shares. Of course, because of this, they wouldn't have need for a written or spoken language, which, of course, makes it difficult for them to leave records behind for the benefit of non-telepathic beings to come after them (such as the humans who wipe them out).

However, the novel actually works around this need by expanding the telepathic powers even further: the queens are powerful enough to connect telepathically with other beings and thus read and transmit thoughts directly, allowing non-telepathic beings to learn from them without having to read any writing.

• When the buggers know that they're going to be destroyed, they preserve their race by hiding a fertilized hive queen pupa in a colony relatively close to Earth, in a location that only the protagonist, Ender, will find. Being a part of the hive mind, the preserved queen contains the entire history of the bugger race, and is able to convey this information to Ender when he touches the cocoon. When the two continue to talk to each other in the sequels, the queen's telepathic text is delimited by carets to remind the reader that she is not speaking normally, but still allows the reader to understand her.

• The buggers are also able to telepathically interact with artificial constructs as well. In order to create this puzzle for Ender to solve. they telepathically access the computer network of the combat school he attended, and extract scenarios that the school's Mind Game, a game designed to psychoanalyze its players and powered by an AI construct, created specifically for him, then base the structure housing their hive queen on these scenarios.