Speaking and understanding speech do not require that the “code” of the language used is completely defined in every detail. The listener (or reader) can still understand an utterance even without having complete knowledge of the exact meaning of all the words and of the exact details of the grammar. We are normally able to understand an utterance spoken in a dialect that is slightly different from our own and are often able to understand utterances or written messages expressed in closely related languages. When learning a foreign language, we are often able to find out the meaning of a word new to us from the (linguistic and situational) context. We can also cope with mistakes and noise. We can cope with mistakes made by a non-native speaker or a child. Applying information from the context and from the situation, we can correct the errors and fill in the gaps. Understanding is not just the “mechanic” or “algorithmic” application of a code or a grammar, it is a creative activity that does not require the utterances we hear or read to be completely well-formed.
Moreover, for our language to work it is not necessary for every word to have a complete and exact definition. And in fact, most words are more or less vague. Their definition is incomplete and is modified by speaker and listener on the spot all the time, leading to redefinitions and shifts of meaning.
Vagueness of utterances and of terms means that the use of language is not and cannot be completely formalized. It is a creative process for which there is no complete description in terms of a formal theory, a formal grammar or a set of algorithms. This incompleteness entails the possibility of misunderstandings that is an unavoidable feature of language, but we should not regard this incompleteness of the language’s system and the vagueness of words and utterances as a defect of language. Instead, it is an intrinsic part of language important for its proper functioning, adaptability and flexibility. Language use is always embedded into a situation and language as a system is embedded into general cognition. The totality of cognitive processes can contribute to its working and this totality cannot be completely described in terms of formal systems.
When a child learns a language, it starts without any knowledge of it. But the intrinsic creativity of language use is what makes the process of language acquisition possible. The child can use words and syntactic constructions without knowing every detail in advance, and its utterances can be understood even if they are faulty with respect to the “complete” system of the language (if anything like a “complete” system even exists).
The ability of the listener to make sense of an utterance results in a certain tolerance for changes. The language of the child will work even if the child fails to completely reproduce the system of the language as used by the previous generation. Innovations (with respect to the “system” as used by the previous generation) might then be adopted by other children. As a result, languages change.
The creative process of language acquisition even works when there is no completely defined target language. In situations where people with different languages come into close contact, they can invent simple pidgin languages. The next generation of children, growing up in an environment where such a pidgin is spoken, can “negotiate” among each other the rules of a new emerging language, resulting in a creole language that is as complete and well-equipped as any other language. This process of “negotiation” is, in most cases just happening through the creative invention and creative understanding of new bits of grammar or lexical code.
And this creative side of language use is ultimately what made the emergence of language possible in the first place. The process of communication does not require the pre-existence of a complete code or system of grammar and words. A more complex system can arise from a simpler one, i.e. language can be extended since speakers can invent new words or meanings and new bits of grammar, and even new kinds of meanings, new semantic or logical “devices”. listeners can understand what is meant by making sense of it, using information from the situation. And this process of developing more complex and elaborate languages from simpler ones may ultimately start with an empty system.
So at some point in history, language was invented. All that was necessary for this to happen was that general intelligence surpassed a certain threshold. I don’t see the necessity of any specific language ability to arise biologically first (although there might be secondary genetic adaptions to it later). However, I am going to explore the problem of the origin of language in more depth in another article.
To sum it up: we are using language, but our knowledge of each language we are using might always be incomplete. This incompleteness might show itself in the form of gaps in the system and in the form of vagueness. Communication still works because it is a process involving creativity on all sides. The “complete system” of language, describable in terms of formal grammars or algorithms, might not even exist since languages are constantly changing through these creative processes.
By trying to separate language as a system from the use of language (and thus separating formal laws from content), linguists are reducing their own understanding of what is going on. I am just hinting at this here; these problems of the scientific approach to language and of the philosophy of linguistics are going to be explored in separate articles.
(The picture, showing people in conversation, is from https://commons.wikimedia.org/wiki/File:Nuovo_regno,_fine_della_XVIII_dinastia,_conversazione,_1352-1336_ac_ca,_da_el_amarna_poi_hermopolis.JPG)