"How many languages do you speak?"
People like me are often asked this question. It is surprisingly hard to answer.
Generally, I've found that the more an obsessive language learner you are, the less you want to pin this particular answer down. A person who has just one language is easy. Lucky native bilinguals have a ready answer too: "two".
But a few weirdos out there, of whom I have to admit I am one, learn languages for fun. And if you push past a small few to study more and more, it gets tricky to decide exactly when you can add a language to the total.
On one hand, there's any obsessive's pride, and the desire to make the number as gaudy as possible. On the other, there's an obvious desire not to be shown to be lying or exaggerating. But more fundamentally, there's the simple fact that there is no easy way to define "speaking a language". You don't wake up one day knowing that you've finally nailed it, in a way you hadn't the day before.
Consider several standards. Do you know a few useful phrases? Are you able to get through a five-minute conversation of standard pleasantries? Do native speakers say "oh, you speak such excellent X"? Can you get around for a week as a visitor without using English? Have you mastered all the core grammar and a useful base of vocabulary? Does it come out fluidly and apparently effortlessly? Are your inevitable mistakes cute and minor, or do they confuse native speakers? Can you read it? Write it? Can you conduct an interview, or be interviewed? Can you have an argument? Can you follow a TV program? What about an overheard conversation? Can you make a joke? Can you understand a joke? Do you dream in it?
I've written those questions in rough order of difficulty. Where would you draw the line? I do something like this: if you get about halfway through that list (roughly to "have you mastered the core grammar and a useful base of vocabulary?" or "does it come out fluidly?") I'd say you "speak" the language. But I'd say you want to get further down the list, perhaps to "Can you conduct an interview?", to say that you are "fluent" in a language. That's my imprecise standard, and yours may be different.
So by that standard, I'm a native speaker of English, I'm fluent in Spanish, German, Portuguese, Danish and French, and I also speak Italian, Russian and Arabic, but not fluently. So when people ask for a number, I try to make it a joke, and say "oh, about six to nine", and let them work out what I mean, if I don't have time to give them this whole long explanation.
Besides this, I've dabbled in learning about a half-dozen more languages, and at one time I could have possibly added them to the low end of the "speaking" list: Dutch, Japanese, Polish and Swedish. And I've done some lighter dabbling in Mandarin and Esperanto. I can slowly read the New Testament in its original Greek with the help of a dictionary. But I don't count any of these. If you lose them, in my opinion, you take them off the list. (Isn't that depressing? But while I once could say "I speak decent Dutch", I just can't say it today.) And I don't count reading a language as speaking it.
As an interesting issue is that of domain. You may know a lot of the vocabulary and fixed expressions of one area, but not another. Usually this depends on your experience using the language. I was an intern at the US embassy in Uruguay, working in Spanish every day; I did my master's thesis research in French on EU politics; I've been a business and finance reporter in German; I've been a general political reporter in Portuguese; I've raised a child in Danish; and I've obsessed over the middle east in Arabic. So I can say "enlargement of the European Union" in French but not Arabic. I can say "proprietary trading" in German but not Portuguese. I can read a newspaper report on the Arab-Israeli conflict in Arabic, but not in Russian. I can say "pee" and "fart" in Danish but not in Italian. I've never been to Russia, and so that language is rusty since my study two decades ago. I still know a lot, but increasingly more passively than actively, and I wonder obsessively over whether to remove it from "the list".
But what list? Who cares? Polyglot nerds mostly just like swapping stories and experiences, and in my experience, as The Number gets higher, they get less and less likely to puff their chests out and proclaim it. They're well familiar with the complexities I've tried to describe here. I've known lots of people to proudly proclaim that they know three languages. But I've never heard anyone boast that they know nine, even though I know people who do. It's because numbers five through nine have a way of humbling you.
Ken Hale, an MIT linguist, was such a prodigious language-learner that it was rumored that he'd learned Finnish on the flight to Helsinki. Everyone agreed that he was extraordinary. But he said that he "spoke" only English, Spanish and Walpiri, and the rest he just "talked in". I like that, and so the older I get and the more of this I do, the more I try to put aside The Number and just have fun talking in as many languages as I can.