It is the same question as do we need "data" at all? We collect data to be used (later)for different purposes. Not all such collection efforts are based on immediate necessity. For good or bad we need fundamental knowledge.

Thank you for your answer Babak!

Well, that's one way to interpret, that it's just "data". But, none the less, then how will you use this data, what is the worth of what you call "fundamental knowledge" and do you then consider that all former dialects should be mapped so that we have "fundamental knowledge" of our linguistic past? 

Maybe you could elaborate on how you think this "fundamental knowledge" can be of any use in modern context? I'm sure we can learn to talk very well without knowing past dialects? So, how can they be of use?

Excellent answer from Steven Jefferson and there's no need to add more.   The functional view of higher education, in this country (UK) at least, has not done it any favours.   Knowledge of all kinds will be useful to humans in one way or another, even if we don't see this utility in our immediate context.

Sure, identity and other aspects mentioned are factors. And mere utility issues are missing the point. Languages and dialects are both lenses and means of expressing how we see the world, and our role in it. Means of conveying views, concerns, beauty, wisdom. That beauty and wisdom cannot be expressed in just the same way in every language. Example: take any ancient text -- religious, philosophical, stories, myths, poetry -- and compare different translations (by different translators, at different times). Preferably, if you can, in different languages. They are often so different that they feel like totally different books; one wonders what happened to the meaning and wisdom of the original text. It may have gotten lost or distorted over time; and being able to go back to the original version and understanding it will be the only way to recover it.

Sure, we need common currencies for everyday transactions. But the common utilitarian currency can often just buy common wares, cheap supermarket stuff, unable to covey the beauty of local, handmade goods, poems, songs. It would be a tragedy to lose all those dialects reflecting the many ways we can be human.

Well, Steve, as you yourself points out so eloquently, obviously there's a great point [meaning] to it. Maybe it's not an immediate necessity for a practical survival situation. But, as you say, we (you, I and Ken - apparently) have the "luxury" of discussing and studying these things. And I believe we can also do this to the benefit of our survival as a collective (humans, global community, whatever you call it). The world as we live it have come to a circumstance where intellectual skills today is just - or at least within the next 100 years - as important than practical/physical capabilities. 

The "point" of studying former languages might for one be, as Steve writes, to be able to understand our past, our history. We might [will] continue to make mistakes, but the best way - it seems to me - to develop into a better state, is to learn from experiences and thus we have not only our individual lives but the lives of a complete race. Deducing meaning, thoughts, history, identity and culture form past human societies is to the collective just as important as meta-cognitive abilities (the ability to think and learn from individual experiences) is for the individual. In some sense, in this context, to understand past language is the tool we need to understand human history. But, this all concerns language in general, and as interesting as it is, (does anyone have more thoughts on this subject?), I'd like to put in my original though, when I first posted this thread.

My thought arose from studying some sociolinguistics and ways to phrase/convey some intentions in different times, languages and dialects. So, I'm not very concerned with the sound of the language or translation as such. I'm interested in the attitude of a way of talking and how that might affect our relationships. This discussion could as such take many path, but my initial reaction was about “politeness”. In danish, we can still phrase a request with “be om” (literally meaning “pray for”), similary to english “please”. Maybe a random “...sweet of you” or “thank you very much” occurs. But, that about covers the common politeness in danish.

It seems this occurs in most languages (I know of), but some are at different stages (?) currently. For example both German and French still have this tradition of “politeness” in language integrated. And both positive and negative things could be said of this. Once (some half century ago) danish where like French or German still are today. As in German you say “Sie” as a polite approach and “du” as a more casual. The distinction occurs especially with strangers, older people and people you show respect (higher hierarchy than yourself), for example teacher and parents. Saying “du” is stating that you are equal and casual together. This tradition more or less died with the rebellious era of the “hippie generation” (70s in Denmark). “We are all equal, thus we should address each other equally”. And it wasn't without reason. The negative effect experienced of this attitude in the sociolect was obviously that a no-more-functional distinction was made about equality between people – just as feminism have boomed from that same time period. While I think that the negative effect of not doing this anymore is the loss of respect, but only in general, which means that I don't believe the solution is to reinstate this “old way of talking”, but rather to reflect upon our language and how we experience and express (attitude) towards each other.

In Icelandic, they are also very blunt and direct. For such and traditional language this seems ironic. Of course, some still exist and words can definitely be found but rarely used – not even, or especially not, by the elderly. (If someone have more experience on this, Icelandic, please correct me!). My experience was also that they talk very blunt and directly. “I want/ give me that” and a mere “thanks”. But, this common attitude also makes it possible to really show gratitude when necessary. “Takk kærlega [lovingly]”. Or “vinsamlegast [friendliest]”. I've noticed that a lot of “learn icelandic programs” employ these “politeness talk”, but in practice Icelanders know you are foreign because “you sound so suspiciously polite” - I experience this personally. On the contrary they are more common to say caring words like “elskade [loved one]” and “minn [my], as an example “Elskade Johannes minn”. To me, with danish and swedish background it almost sound ironic and rude, almost degrading. To hear that so commonly to so many different levels of friends is strange. But, once I got used to it, is sounded so wonderful and warming. So much simple love and caring. Maybe on this random thread: https://answers.yahoo.com/question/index?qid=20080824223426AAXTuZV Icelanders makes the French seem pleasant. Funny.

As mentioned, the lack of general “politeness” fascinates me. Maybe we are more efficient without all that politeness-jidder. Maybe we distances us self from each other by being so blunt? So, as to the point of the thread: are there any cultural worth in former ways of talking, have we lost something along the way or become more developed? I'm not sure of the consequences but sure believe that it does have a lot of consequences – to culture, identity and the development of communication.

Is it a good or bad thing, that politeness seems to change in time and between languages, and how is this in your own first language?

Thank you for your reply Thorbjørn! 

It's very nice to get that point emphasized and I definitely agree. So much is "Lost in Translation", but hopefully sometimes, something new can rise from it as well. 

Knowledge of historical linguistics is invaluable in explaining certain "exceptions to the rule." You can't explain modern English, for instance, unless you consider Old and Middle English.  For instance. there is an alternation in consonants lie [f] and [v], [s] and [z] and the th sounds. Examples are singular and plural final consonants as in [loaf, loaves], [knife, knives] and [wolf, wolves.] [life, lives.]  and [leaf, leaves.]  We also see this alternation in [ give, gift].  This signals a different in parts of speech, not singular and plurals. Similarly, [s] and [z] sounds alternate in  [loss, lose, lost], and [choice, choose]. Note here, that the [z] is spelled with an [s] in [lose] and [choose] and the [s] is spelled as [ss] in loss and the [c] in choice, indicates an [s]. Although there are two pronunciations of the digraph {th},but that can be two different sounds, as in thin,and thought, as opposed to the,  this, and they.  Thigh vs. thy both are spelled with [th], but they have two different pronunciations.   We have no letter in English for the first sounds in this and they.  I know you're thinking "English is an inconstant language, but that doesn't explain the variation in pronunciation of the same spellings.  Going back to Old and Middle English, we see that this irregularity in spelling comes from an old phonological rule in which a [f]] sound became a [v] when it was between two vowels as in give, again noting that the final [e] in give was pronounced even down to Chaucer's days.[s] it was followed by a vowel.  Note that the [e] in lose was pronounced in the olden days.  

As for the two {th] sounds, they arise from another circumstance, which you can find explained in my blog, The Language Lady, which can be accessed by going to www.elainechaika.com and, on the top of the opening page, click on Blogs.  At the very least, looking at old dialects explains why English spelling is so chaotic.  Part of that is the fault of the French scribes whose pronunciation rules were different from English.  The two [th] sounds illustrate this.  The French didn't have either sound in their language, so they invented the digraph [th] and used it for both pronunciations. In Old English there were two separate letters for the different sound in this and thin.

If Wordpress allows me to use the phonetic symbols, I will explain this in more detail, but, to answer the original question, not only do older dialects shed light on the modern language and its spelling, but it gives us insights into how people perceive language, but also gives us insight into the many ways to signal words with sounds.