If you could bring an English Speaking person from 100, 200, and 300 years ago into modern day, how difficult would it be to communicate with him\her?
Interesting idea — off the top of my head, I’d say three or four hundred years isn’t that big a deal, so I think the main issue would be technological and cultural changes, rather than language per se (assuming you avoid trendy slang, regionalisms, football metaphors, and such). Going back five or six centuries, it would be progressively more difficult to understand the spoken language (due to the Great Vowel Shift). Anything over a thousand years (before the Norman Conquest), and you’d be better off speaking to him in Dutch. Another option would be to use a more stable language that your time traveling Englishman might happen to be familiar with — most of the Romance languages would still be reasonably intelligible, especially if you’re familiar with more than one. Going back 2000 years or so, you’d have to count on your Englishman’s having studied a popular classical language like Latin, Ancient Greek, Arabic, or Hebrew. He probably wouldn't be familiar with Chinese characters, but it wouldn't hurt to try.
You can search newspaper and other historical archives to see if you understand the language. For example, this link is to an article from the New York Times in August 1916: http://query.nytimes.com/gst/abstract.html?res=9E04E7D61E31E733A05752C3A96E9C946796D6CF&legacy=true
The language is all current and totally comprehensible. A modern reader would regard the style as very formal but most would not strain to read it.
You might find this article interesting:
By the way, @Phil, where might an Englishman of 2000 years ago have lived?
Judging by the written word, for me, there is a turning point somewhere in the 1700s. There are many novels from the 1800s that I can read without effort and with genuine pleasure. I can't say the same thing for the 1700s. I really did enjoy Tom Jones. But Tristram Shandy? Gulliver's Travels? A Journal of the Plague Year? I got through them, I sort of enjoyed them, but I haven't re-read them. When I read them I had to work at it. And my pleasure was supported by the knowledge that I was reading a classic. It's not just the language.
By the time you get back to the 1700s, the cultural background has become so different from mine that I can't really make sense of what I'm reading. For example, it starts to be difficult to read between the lines and tell whether couples are having sex!
I can imagine myself communicating, with difficulty--much repeating, much speaking slowly, and much backing up to find simpler words--with someone from 300 years in the past.
In Mark Twain's The Adventures of Huckleberry Finn, he says:
In this book a number of dialects are used, to wit: the Missouri negro dialect; the extremest form of the backwoods Southwestern dialect; the ordinary "Pike County" dialect; and four modified varieties of this last. The shadings have not been done in a haphazard fashion, or by guesswork; but painstakingly, and with the trustworthy guidance and support of personal familiarity with these several forms of speech.
It's a novel, not a dissertation, but nevertheless, based on Twain's writing, I have the impression that I could communicate easily with Twain or with any well-educated person in the middle 1800s--but that I would have trouble with less-educated speech:
Blamed if the king didn't have to brace up mighty quick, or he'd a squshed down like a bluff bank that the river has cut under, it took him so sudden; and, mind you, it was a thing that was calculated to make most anybody sqush to get fetched such a solid one as that without any notice, because how was he going to know what was tattooed on the man? He whitened a little; he couldn't help it; and it was mighty still in there, and everybody bending a little forwards and gazing at him. Says I to myself, now he'll throw up the sponge—there ain't no more use.
Spoken rapidly? And in what to me would probably be a foreign accent? Tough.
And in the 1800s there would have been a lot more less-educated speech than there is today. Radio and television have had a big educational effect.