How many languages can a person reasonably know?

Question

I was looking at this video about Japanese Kanji on youtube, and found a discussion where people were talking about learning too many languages. Several claimed that they started to forget English because they had to invest so much time into Kanji. Some people were reporting the same problem from just trying to pick up too many. Others made claims like they started to get the languages and/or alphabets they knew mixed up, or they would start speaking English in a foreign accent, or they now seriously have an easier time speaking languages OTHER than English. And these are coming from people who only know 3 or 4.

I have heard stories of highly gifted people knowing over a dozen languages (and actually being fluent in 5 or more of them too). But how many can the average person seriously know? From what I've seen its rare for someone to know more than 2, but of course I'm American, its hard to find anyone here who isn't monolingual (aside for the Hispanic immigrants, but even a few of them are monolingual). I know my German teacher knew English, French, and German (her native language). She also taught a Spanish class, so I'm guessing she also knew at least some Spanish. She also claimed she knew Latin, but couldn't speak it fluently.

But really, how many languages can the average person know? I myself already know German up to an intermediate level (though I struggle to form my own sentences now, but I've been trying to find a way to correct that). I would like to learn as many as possible, but I don't know how many I can handle. I did have an issue when trying to study Japanese while I was taking a Spanish class (specifically my issue was both languages have an adposition called 'de', which means different things in the two languages), of course that was because I was trying to study two languages simultaneously.

Answer 1

The limiting factor for the average person is really the society, the environment.

We humans are lazy or, from another perspective, efficient - most of us try to learn only the minimum needed to function.

So just like there are certain societies where knowing two languages is totally normal and expected, there are societies where knowing three is normal, and even four or five.

For example, average middle- or upper-class people raised in Lebanon almost all know Lebanese dialect, Standard Arabic, French and English. They know them all fluently and functionally. Nobody said that they know them all perfectly or equally.

Lebanese dialect is the main language on the street and in the home, Standard Arabic is used in school, French and English are learnt as foreign languages but very dominant in product packaging, news and now social media, technology and certain business domains.

It's not as if door bell buttons, television menus or internet addresses always have Arabic letters. Vehicle registration plates have both Arabic and Latin. Reading Latin letters is necessary to function, if reading Chinese were as necessary to you to function you would know the basics of it.

So then within Lebanon and western Syria there are small communities like the Cretan Muslims or the Armenians who often know their own languages - Greek and Armenian - usually in addition to all of the above.

To be very clear, such people are obviously not all geniuses, not all good students, not all hard-working. Each language is just added per its daily necessity or usefulness, often from an early age, keeping in mind that adding similar languages is easier. (From a Semitophone perspective, and even from a Grecophone or Armenophone perspective, English and French are very similar.)

Similar conditions exist for many people in Europe for example in Belgium, Switzerland, South Tirol, the Basque Country, the Banat, Transylvania, Moldova, Luxembourg, Georgia, Armenia, Slovenia, Åland and among the Romani and various other traditional or modern linguistic minority milieus, and for specific families or individuals. And they are common in many places in Asia - notably India - and many places in Africa and a few places in the Americas.

You asked about atrophy or interference. Well, yes, it happens. But if it is happening in roughly equal measure to everybody around you too, then nobody hears it, it just becomes a feature of the dialect. All of that is a separate question though.

So what is the concrete integer? There are individuals who know twenty languages but I do not know of any environment where twenty languages are actually necessary or at least useful to average people in their daily lives. So we do not know that it is possible, but we do not know that it is impossible.

Answer 2

You've got great answers so far, but I may contribute somewhat. I'm a language learner myself, with a grasp of 3 languages - English, Italian and Portuguese. Recently, I realized I wasn't so good in any of them, so my wanting, as the ambitious person that I am, was to reach fluency on all. What an omg moment I had.

It might not look at first, but each natural language is an enormous body of infornation, with thousands of rules, constructions and we can't forget all the different ways of thinking imbedded within it. We obviously don't need to know all that but the sheer amount that we must know in order to communicate well in most stances is still considerably big.

Now, answering your question; we cannot say. As I've shown, normally, mastering a language requires a great deal of effort, but if you are naturally gifted or simply do what it takes in order to learn and keep the languages inside of you alive, you can learn many. I personally think 3 languages suffice me, but if I ever need to learn a fourth for whatever reason, I'd consider it to be right next to my hinge of maintainability, if not sligtly above it.