Linguistics is the study of language which comprises present and historical language and speech. However it seems that the concrete object of language is difficult to define. This is because language is multidimensional and includes speech, sound, physical and psychological aspects. Thus, it is easy to discover the mechanics of a language, but much more difficult to see how and why and language changes or differs from another language, or more specifically, where does the meaning lie in language. Saussure is known for the theory of the arbitrariness of the sign, meaning that linguistic form is not related to meaning in any relevant way. Specific languages, however, gain meaning through their collective usage.
Because there is no accepted definition as to what a language is in relation to a dialect, accent etc., it is difficult to prove where one language starts and another ends. Consider the Arabic language, where each country has Modern Standard Arabic in addition to one or several regional dialects. The regional languages differ greatly from Saudi Arabia to Morocco, so much that the intelligibility between dialects might be similar to intelligibility between Italian and Spanish, which are considered distinct languages and not two dialects of the “standard” Latin. This is not including the ease with which languages adopt and adapt new words from other languages, for example telephone, computer, and calculator. Thus, it seems a difficult and impossible task to neatly divide languages into separate and distinct categories.
And if it is not possible to separate languages, how can we be so sure that everyone on earth is not speaking the same language! For sure, there are no people on earth which are so completely distinct as to not have in common at least one shared communicatory element. The word tea in English which is originally from Chinese, translates to téin Spanish, thé in French, shai in Arabic, chai in Persian and Indian, cha in Chinese and Korean. One could argue that these are different dialectical pronunciations of the same word, or in contrast, completely different words although they have the same origin. Neither analysis would be more correct than the other. How can we be sure that humans are not in fact speaking one large language? For even when one is observing two others speaking in a foreign language, is there not any meaning or information which is conveyed or sensed to the observer, however slight and remote it may seem.