From linguists (philologists) one very often hears the following objection: even if all inhabitants of the earth learnt one and the same language, the unity would soon disappear, and different languages would arise in the same way as the Romanic languages were produced by the splitting up of Latin.
Against this objection I have two critical remarks: in the first place, the argument from linguistic history is not sound; and secondly, if it were, that should not hinder us from working for an international language.
It is quite true that the history of languages often shows us a tendency to differentiation: it is well known that most European languages have taken their origin from one and the same language. But the tendency towards differentiation is by no means inevitable. Those who believe that a language must everywhere and always break up into a number of dialects forget the most important law of linguistic biology, namely that constant intercourse creates linguistic unity, even where it did not exist, and that discontinuance of intercourse produces linguistic differences where there was once unity. If after the colonization of Iceland the Icelandic tongue came to be different from Norwegian, this was due to the cessation of constant communication, and if nowadays the speech of California is in perfect agreement in all essential points with that of Boston, this is due to the fact that the inhabitants of the western and eastern parts of America are in very active intercourse with one another. Antiquity witnessed many cases of differentiation of languages; we nowadays see more of the reverse process - dialects are everywhere disappearing, and unity is constantly increasing: an ever-growing number of people speaking the great national unity-languages. Thus the only condition under which an international language once adopted would split up into different languages, would be the want of constant intercourse; if for example a colony of Novialists (or Esperantists) emigrated to a previously uninhabited land, and lived there entirely isolated from the rest of the world. But such a supposition is evidently absurd, and we must insist that as long as an interlanguage continues to be useful in its true function as an aid to intercourse between different countries, there is no danger that it will suffer the fate that befell Latin, when that language was split up into the Romanic languages.
Even if we admit for a moment the possibility and probability of such a differentiation, this ought not to deter us from working for an international language and speaking it. Those who think that any language must by a natural law necessarily and fatally differentiate, will nevertheless speak their mother-tongue every day without being afraid that in accordance with that fatal law it will split up under their hands. And this is quite natural, for such a differentiation is not a matter of a moment; it will take some time, even a long time, and we may confidently assert that it will not take place during our lives. We can thus say: After us the deluge! But, as I have already said, I do not believe that even after us the dreaded linguistic deluge will take place.