Re: Conversation with a mute
Yes, I agree with slack -- I wasn't sure how to think about the question because I didn't know how much she understood.
If she's forgotten how to form spoken language that's one thing -- and presumaby she understands the way in which languages work and words are used to symbolise things (you know, the whole thing about the word 'dog' never having bitten anyone). Then she could be using gestures etc. to communicate pretty complicated ideas or drawing things in the dirt with a stick. Presumably in this case the issue is with expression of ideas rather than generating them -- sort of like someone who has had a stroke? I believe that in real life articulating things is normally the problem (although I'm basing that on 15 second conversation with my husband and I didn't explain the whole context).
If she's forgotten language completely, though, then how is she thinking? I don't know how language and thought are connected -- but I think they might be. For example, in 1984 language is assumed to shape not only your perception of the world but your ability to think. So by changing language, the government changes people's ability to think rebellious thoughts. I know 1984 isn't a psychology/ lingustics text and no doubt theories about this have moved on a bit since the 1940s, but it's a nice illustration of the idea that language defines thought.
If she has no recollection of anything that's one thing -- like amnesia -- but I think people with amnesia normally remember how to talk because that's not a memory as such, it's a skill repeated so often that it has become automatic -- like they remember how to walk and eat with a fork. But this is magic, so that works OK for me that she would lose language but retain the ability to do other stuff. If she knows nothing of anything before a certain point then I guess she's basically being born again and anything she thinks has to be at a very instinctive level - so there's nothing to say she shouldn't be in a forest with this man because that's the only reality she has ever known - that's what she's been born to.
In answer to your question -- I think she's forgotten how to *produce* language, right? Because she understands the man enough to answer yes or no. So she can sign, and he can be teaching her language again. If she once had language then presumably its a case of reminding her rather than starting afresh and she should pick up the basics pretty quickly. If she can't articulate it then signing or pictures is a good way to go - though I agree that focusing on the details of the communication is not as interesting as what they say. If you'd like to know more about this then you could look at stuff on how non-speaking people/ people with complex communication needs communicate -- there's established signing language (e.g. makaton) and also pictograms which are used to help people express their thoughts.
Sorry - that's an essay.
(Disclaimer -- I don't really know what I'm talking about, but these are questions that occured to me when I was reading your bit above -- and someone else might know the answers...)