How Much Do You Need To Know To Be Fluent ?
Here is a link to a very interesting article I just read.
http://howlearnspanish.com/2010/08/how-many-words-do-you-need-to-know
and the executive summary is here:-
Right, let’s get down to brass tacks. According to the above study, for Spanish:
1.Learning the first 1000 most frequently used words in the entire language will allow you to understand 76.0% of all non-fiction writing, 79.6% of all fiction writing, and an astounding 87.8% of all oral speech.
2.Learning the top 2000 most frequently used words will get you to 84% for non-fiction, 86.1% for fiction, and 92.7% for oral speech.
3.And learning the top 3000 most frequently used words will get you to 88.2% for non-fiction, 89.6% for fiction, and 94.0% for oral speech.
and....
“Assume that a language learner is aiming for 90% coverage in each of the four parts of speech that represent open classes — nouns, verbs, adjectives, and adverbs. This 90% figure will be obtained by knowing about 2600 nouns, 230 verbs, 980 adjectives, and 50 adverbs, or a total of about 3800 total forms.” ]
6 Answers
Well, my opinion is that words themselves are of small use if you don't know the grammar, the verb tenses, the idioms, etc. However, I do agree with this article in that most of human speech and writing is represented by a small number of commonly used words.
Some people want to know how tall the mountain is. Well, it's hard to say. How fit are you? That's more relevant than the number of vertical feet of the mountain.
I would recommend learning how to conjugate an irregular verb like "dar" before trying to bean-count how many words somebody knows. There you get the reality that many "words" are merely forms of one word, and it does you little good to know only the one form of that one word.
I think it's probably true that a small base of words gets you to THEORETICALLY be able to translate x% of conversation, but that is a very misleading equation that has nothing to do with real life.
In my own mind and for my own purposes I have set the bar at knowing 1000 verbs as the base to be conversant (not fluent). That doesn't mean only knowing the infinitive form either. I can tell you that even this has major limitations when reading the news because by golly there are a LOT of nouns, a LOT of adjectives/adverbs and a very strange use of pronouns, just to name a few of the issues.
The real question isn't how many vertical feet you have to climb but how fit and how motivated you are. And bring some water.
I got on really well, when I only had three tenses:
The present indicative. Lo hago.
The past by using haber. Lo he hecho.
The future by using ir. Lo voy a hacer mañana.
I was quite happy and fairly fluent.
Then I wanted to learn more, and hit the brick wall of the subjunctive, the preterite, the imperfect.. Well, three consecutive, well built brick walls in close proximity.
I actually lost any previous fluency, for having to half-halt at every verb...
So, yes, you can manage fine with only three tenses, but you have to have a fairly good vocabulary to circumnavigate any problems.
Really, it may be better to adopt a more thought out learning plan. I really don't know.
Lo de aprender, cuesta. Learning takes it out of you!
It's not learning "words" but memes, or meanings. A word can mean different things depending on how it is used. Bean counting words should be changed to learning phrases, or heaping of words. Fluency means that you do not hear individual words but groups of words -- idea by idea.
For example, "that was a stupid thing to do". But it is loses its meaning if you decode each individual word. My fluency mind should be translating, he said that I did something stupid.
Lot´s of good answers so far, all of which I´m going to go back on vote up in a minute here.
Despite being an engineering and stats guy, I find those stats to be virtually meaningless.
The only interesting, though to most, probably already obvious part, is that we don´t need that many words to hypothetically understand a large number of concepts (and that the returns thereafter, are very much of the diminishing variety). Sure, 10% of the total words out there in a language can probably fairly well communicate 90% of what one needs, but when the meanings aren´t concrete and literal, and doubt those numbers stand.
But, if you look at the vast number of forms just a single verb can have, even a regular one, much less an irregular, the statistics start to mean much less.
Then, when you add in idioms and connotations, it gets worse.
I´m not all that embarrassed to admit I can pick up pretty any random adult book or passage, and quickly find a sentence or two, where I understand every single word, but yet, where I really don´t know what the sentence means. I think that´s fairly common. I just don´t think the statistics are relevant here.
Still, I´m a geek and love reading this stuff. And the article may offer some hope to beginners, that they needn´t learn 10,000 words before they can converse fairly well.
Of course, we will all have collectively shot that hope down, but hopefully not completely 
I have NO idea why that just double posted. Sorry. This is as much as I can erase it.
