Could Esperanto seriously become the lingua franca?

Esperanto was created at a time when there was no agreed upon lingua franca. To intellectuals in the late 19th Century, creating a logical and neutral language was seen as a great solution to this problem and a large number of artificial languages were created at this time including Esperanto. However, the time for Esperanto seemed to pass when English become the dominant global language. It's possible that if English ever loses it status, Esperanto will have another window of opportunity, but it's an uphill battle as Esperanto has a small user base compared to other potential lingua francas.

English will win the battle, because...well, because Internet. English is the dominant Internet language, and the internet is our means of communicating in a world-wide-way. :) It's interesting, because I know that Spanish's influence on the USA is changing language dynamics here, but ultimately, if you can't look up specific things in a non-dominant language, you can't get ahead. As a resource, the Internet is insanely popular and useful, and knowing English is the ultimate way to use the Internet well. I used to live in rural Mexico, and when someone asked me a question I didn't know the answer to, I'd find the answer fast (in English) and then explain it to them (in Spanish). Because we are so heavily invested in online resources, I just see no chance of Esperanto, or any other language, catching up. Mandarin might have a shot, but I doubt it. http://en.wikipedia.org/wiki/English_in_computing http://www.cs.tut.fi/~jkorpela/lingua-franca.html

If "could"  means  "is the language sufficiently rich to be able to be used for this purpose?"  then I think the answer is yes.   If "could" means "is there a realistic set of circumstances under  which it might actually happen?", then I think the answer is no.  Those who learn esperanto in expectation of some eventual "Fina Venko" [ultimate victory] may be doomed to disappointment and disillusionment with the language.  Or perhaps they will live a lifetime of hope (true "esperantists"!) for some messianic future without ever seeing its fulfillment. There is a third option, in which the dream of Esperanto becoming a universal second language diminishes in importance, and the pleasure of using the language as it is, in the world as it is, is enough. Almost as irrational as finavenkismo -- yet every bit as strong and very well documented in the history of the language -- is  the drive to create doggerel Esper' por ia venko fina estas revo halucina; Kaj la lingvo ne bezonas motivon kiu malrezonas

Sorry, Katie. You're wrong about English being the language of the internet. You clearly don't access sites in Welsh, French, German, Chinese. There is an English presence in the intermnet, it's true, but it is a small percentage of all the sites. Many internet users never access an English site.

It certainly could, but the problem is the vast amount of knowledge we as a species have produced in english throughout history. In science for example, you need your papers to be read widely and cited by others. Additionally, you need to build upon work done by those who came before you. Unfortunately, the largest groups in each of these categories (readers, future writers, past writers) are those who speak or published in english. There would need to be a conscious effort to move away from english in order to establish esperanto it its place.

To become a lingua franca means to gain more and more people who learn the language - so did English and before that French, Latin and others. Usually this lasted several centuries. So the first part of the question is: Could Esperanto gain more speakers? The main target group for Esperanto learning are youngsters between 14 and 25, following a higher education. The main problem is, only a few of them know about Esperanto, very few know enough to decide whether to learn it or not (probably less than ten percent of them). If they are informed, usually about two out of hundred of those learning a foreign language (like English) will learn Esperanto. (In the theory of the "https://en.wikipedia.org/wiki/Diffusion_of_Innovations" such people are called "Innovators".) If it would be possible to inform all youngsters between 14 and 25 about Esperanto and how it is used today, probably the number of Esperanto learners would increase very much, maybe even ten times compared to today. This would mean, following the mentioned theory of the "Diffusion of Innovations", that the time would be ready for the next group of "Early Adopters". They adopt something after the group of Innovators, and they do it, because they feel it's useful - and, certainly, Esperanto would be much more useful, if it had ten times more speakers than today... I do not say, that such a way is probable - but I suppose, it could be. The main question remains, how to inform all those young people... One of the usual objections is that Esperanto did not achieve the goal of becoming a general lingua franca during 125 years, so it is not very probable that it will ever succeed. No, not true. English needed about 1500 years to become a general lingua franca. So Esperanto still has a chance. And, I think, Esperanto already did a great job. In 1887 it had about five speakers and so it had the smallest group of speakers of several thousand languages. Today Esperanto is probably one out of the first fifty or hundred languages which are most used. It is foreign language number 18 (or so) in Hungary, see http://www.nepszamlalas2001.hu/hun/kotetek/18/tables/load1_32.html. It is language number 32 in the https://meta.wikimedia.org/wiki/List_of_Wikipedias#100_000.2B_articles. It is one out of about seventy languages available in http://translate.google.com/#en/eo/. You can get Firefox in Esperanto, Facebook, Linux... I think there won't be a chance for Esperanto to win against English - if it is confronted directly. It is clear that nearly everyone will learn English before Esperanto. But some people do learn a second or a third or even a fourth language after English. Then Esperanto is worth thinking about. Because you easily can have contact with Esperanto speakers in nearly every country worldwide - something which is rather  difficult with national languages. (Spanish is useful in Spain and the southern part of America - but doesn't help a lot while in Japan or in Russia... But Esperanto does, the Esperanto speakers are well organised, you find them easily in nearly every country.) And, Esperanto is much easier to learn, you only need about a third of the time. Or, if you study more, you become much more fluent in Esperanto than in other languages. This is a serious advantage, if compared by a youngster who does not want to visit always the same foreign country, but to travel around. So Esperanto, maybe, could one day become the first out of the languages learnt after English. Then, probably, it would become more and more attractive - and, maybe, surround English. Very difficult to decide, if this would really be possible. And even more difficult is the question when this would be. (But we know that Esperanto can be learnt rather quickly, so it may spread rather quickly.) Just have a look on http://en.lernu.net to get a first glance of Esperanto.

It definitely could. A longterm prediction would be that it could take about 200 years, if current growth keeps going the same way, but it will probably at some point exponentially go through the roof, so a more risky prediction would be that in 50 years Esperanto really becomes a dominant lingua franca. As English learning is going down and Esperanto learning is going up, I would definitely not bet on English for the long term, also because connectedness by means of the internet goes up, and "your neighbour has to speak the language for it to be useful" is now definitely not true any more. Even when it was, Esperanto was always growing, so now Esperanto is definitely going faster than ever.

Unfortunately, history shows the idea of a universal synthetic language is at best an aspiration. Cognitively, the brain has modalities for language processing, so when you ask someone to learn a new language, you are not only asking them to adopt a new way of speaking, but a new way of thinking. People generally don't want to adopt new ways of thinking.

Esperanto already is the lingua franca for those 2 million people who already. Check http://www.lernu.net