What would the world be like if everyone spoke the same language? If no one spoke at all?

If everyone spoke the same language, hopefully that language would be really, really creative.  I guess the first question would be, what language has all of humanity adopted?  English, Chinese, Latin, something entirely different? And would there still be accents? Ultimately though, I think the world would be a less interesting place for it.  A bunch of languages have words that don't translate well into other languages.  For example, German has such gems as Innerer Schweinehund, which roughly translates to inner pig dog, and is apparently for the little voice in the back of your head saying that you should give up on life and be lazy.  There's also Dreikäsehoch which means three cheeses high, and is talking about height (the person is as tall as three cheeses on top of each other), not weight.  While they can be translated(ish), there is no word for them.  There's also many sayings that just don't come across the language barrier as well.  My mom, for example, like some of the other parents people mentioned in class, had a different language (Vietnamese) as her first language.  So she often says these proverbs in English, but none of us (me and my siblings), are really sure what she means.
Words: http://www.fluentu.com/german/blog/weird-german-words-vocabulary/
Even with only one language, people would still miscommunicate with others.    Ludwig Wittgenstein said that misunderstandings occur because people use words to convey pictures to others, but people don't always have the same images in their minds.  Though there would no longer be an language barrier, there would still often be an image barrier. 

If no one spoke at all, the world would definitely be a quieter place.  But though there would be no shouting, there also wouldn't be any singing.  I guess people would just use sign language, but would there be one sign language, or multiple regional languages?  Also, going back to the German words for earlier, would those still have a place in language?

The world would be worse off if everyone spoke the same language, because though everyone should be able to understand each other," there would still be miscommunications, and the world would be a duller place.  The most important reason of all, if we all spoke one language, we would miss out on the joys of hearing Pewdiepie swear in Swedish after being scared/frustrated/surprised by a videogame.

What counts as acceptable justification in each AoK?

• The Arts:
• An award, for the piece of art ( Example: Saying the musical Hamilton has the best music would be justified by the fact that Hamilton won Best Musical Theater album at the 2016 Grammys- though one could still argue the award is subjective..)
• Maybe also price, if it's on the market ( Example: A Van Gogh went for what would now be 83 million dollars in 1987.  I hope someone wouldn't be paying that much for something they thought was terrible...)
• Ethics
• As long as it doesn't hurt anyone else (This is probably kind of questionable, because if you think life begins at conception, pro-choice would be hurting someone else)
• History
• Facts, from multiple sources, preferably primary souces
• Mathematics
• Proofs, which require logic to be true
• Human Sciences
• Personally knowing a person (though this not might be the best, given the number of people when interviewed about those who commit mass murder, and say they though the person was perfectly normal)
• Experience (definitely not perfect, generalizations always have acceptions) 
• Natural Sciences
• Results from an experiment that had repeated trials, and is repeated by other researchers
• Religous Knowledge Systems
• If one believes in a set of assumptions that can't be proven or disproven, someone could use those as acceptable justification (but someone who doesn't believe it would argue the fact that it can't be proven means it can't be used as a justification)
• Indigenous Knowledge Systems
• What happens in the world around them, that may have been caused by the system they believe in
• ..... sorry, I'm not sure I know what an indigenous knowledge system is....

These are supposed to be acceptable, not perfect justifications.  But if you have something better (and you probably do), comment! Unless you already wrote it on your own blog.  But you could still repeat it, if you want.

Three Questions

1. Can we really leave the cave behind, or do we just walk out of one cave and into another, bigger one?  (Plato says the prisoner is eventually able to stare at the sun, but is it really the sun, or just an artifical light?)

2. What is the point of the character Glaucon?  From what I can tell,  all he does is agree with everything that Socrates says.

3.  Are the scientists who support plant neurobiology in the position of the prisoner who has gone outside and come back to the cave?   If so, or if not, why?