[Update] A Global Perspective on Bilingualism and Bilingual Education, from the Center for Applied Linguistics, reports that “available data indicate that there are many more bilingual or multilingual individuals in the world than there are monolingual.” Experts debate what it means to “speak” a language and even what a language is. For example, most scholars agree that spoken Cantonese and Mandarin are different languages, even though they share identical Chinese writing. However, Cantonese is often referred to as a dialect of Mandarin. Are the 71M Cantonese speakers, the majority of whom also speak Mandarin, multilingual? I believe so, but I don’t think they were included by the sources used for my analysis above.
I was conservative in my analysis, so I do think it is possible that a majority of the world speaks more than one language; however, almost half of the world’s population still lives in rural areas where people are often monolingual, although in China, everyone learns Mandarin, in addition to their local language. Everyone agrees that multilingualism is increasing, but I haven’t seen reports with credible numbers that quantify the trend.
I found it quite interesting to see the number of secondary speakers, with the largest being french (although there are plenty of folk on the web who argue with his assessment).
It is notable that the margin of error in looking at the number of speakers is quite large, and this study seems to have taken the lowest of each estimate . According to a summary by M. Turner, the number of second language speakers was 571 Million, which is 8.3% of the world population.
In looking to update this list, I took numbers from Wikipedia and Ethnologue, surveying the largest languages where I could easily find stats of second-language speakers. Here’s the list I came up with (number in millions):
*Wikipedia reported 100-171 Million (I took the average)
In summary, 2.4 Billion people would be 35% of the world population; however, the percentage of people should be somewhat less since this rough assessment doesn’t account for people who speak more than 2 languages, but I would also guess that in these stats I would show up only as an English speaker, even though I speak other languages also… how would any statistician even know about me? So, this summary is far from scientific, but it feels about right that in today’s global economy roughly a third of us are speaking another language.