Language, even a particular individual language, is far too complex a subject to be studied in its entirety by any one researcher. There is a higher-level distinction we can make concerning what research is supposed to be about, between the study of language as system and the study of language behavior. In either of these two cases, the language scientist is normally studying only some aspect of the phenomenon, one or more of four sorts of things about a language (or dialect): its sounds, its words, its grammar, and its use in context. A researcher interested in the sounds of the language (or dialect) might try to figure out what the basic sounds of the language are, how they combine to form words, or how speakers produce the sounds. Many researchers in this area believe that it is possible to study the sounds of a language more or less independently from the other aspects of the language.
A second area of research is the words of a language, usually thought of as organized in some sort of abstract dictionary, referred to as the lexicon. A researcher interested in words might study how speakers find words when they are formulating sentences or how abstract meanings build on simpler meanings (how is over in get over a problem related to over in jump over the puddle?).
Another possible kind of research would try to characterize what counts as a possible sentence in the language, that is, what’s grammatical in the language. It is not as easy as it might seem to define this concept. We must be careful to avoid any bias on the speaker’s part based on what they have heard from teachers of their language in school because what we care about is what people actually say, not what someone tells them they should say.
But we also cannot just treat any sentence that occurs as grammatical because people make speech errors. By “errors”, we do not mean that they break rules that apply to dialects other than theirs (for example, by saying ain’t or he don’t). Instead we mean slips of the tongue, false starts, and hesitations. For example, the following example includes several speech errors.
Well, I think you … I mean, the … the … um, this isn’t coming out right at all.
People produce such “sentences” all the time, but they clearly also know that there is something wrong with them. That is, linguists probably do not want their descriptions of a language to include such sequences. So grammatical sentences are possible sentences that do not contain speech errors.
This is not to say that there is nothing interesting about speech errors. In fact, like human errors more generally, they can give us lots of insights about the underlying mechanisms. There is a whole community of researchers that take speech errors of one kind or another as the data they try to explain.
Degrees of Grammaticality
But there is another complexity; grammaticality doesn’t seem to be an all-or-none matter. That is, while some forms may be completely acceptable to all of the speakers of a given dialect all of the time and other forms may be completely unacceptable to all of the speakers all of the time, there may also be intermediate cases that are not so clear. For example, some English speakers use a chalk for a stick (or piece) of chalk; others would be less comfortable with this (though they would not find it as unacceptable as, say, a clay for a lump of clay). There may even be variation within a single speaker. For example, an English speaker may say for my wife and me on some occasions and for my wife and I on others.
Returning to the examples we see that by the definition of grammaticality that linguists work with, such sentences as this one may be perfectly grammatical for the person who said it: “He don’t mean nothin”.
A complete description of the grammar of these people (and the community of speakers that they belong to) would have to specify just what counts as a grammatical sentence and what doesn’t (for example, he don’t nothin’ mean or he don’t meant nothin’), possibly singling out areas of grammar where there is disagreement and variation among the speakers. This description would obviously have to say something about word order and about which forms can go with which other forms (“meant” can a perfectly good word in a dialect, but not following don’t).
But some linguists are not satisfied with just describing the grammatical sentences because this says nothing about what those sentences are for. Instead these linguists are concerned with describing how meanings and functions of language relate to words and grammatical sentences. So a grammatical sentence (for some English speakers) doesn’t help us understand how this sentence conveys information about some person familiar to the hearer and about the speaker’s belief about that person’s intentions. Hence, what should we be saying how language accomplishes things for speakers and hearers?
Finally, those same linguists who are interested in how sentences convey meaning may also be interested in describing a fourth sort of aspect of the language, a sort of “correctness” that is different from grammaticality. A sentence can be grammatical and meaningful — that is, the words and grammatical patterns in the sentence can sound right and correctly describe some possible situation in the world — but the sentence can still be inappropriate. Consider the following sentence:”There is no life on the moon.”
This sentence makes perfect sense and describes a true state of affairs. But if you walked up to a stranger on the street and said it, they’d think you were crazy. It would not be an appropriate way to begin (or end, for that matter) a conversation with a stranger. Just as speakers of a language have knowledge about what is grammatical in their language, they also have knowledge about what is appropriate.
Of course not everyone who uses a language or dialect knows how to do so grammatically and appropriately in all situations. In particular, language learners have only imperfect knowledge of the language or dialect they are learning, and they can be expected to make errors. Children learning English as a first language may say “doos” for juice or me up when they want to be picked up. Teenaged speakers of English as a first language may still commit errors of appropriateness, using informal expressions such as bigtime in formal contexts. And adults learning English as a second language may say “diss” or “dees” for this or I make the homework for I am doing the homework. We consider these to be errors, but there are only errors from the perspective of the system defined by the behavior of the adult native speakers of the language or dialect that is being learned. Such examples can also be seen relative to the learner’s own linguistic system, which has its own pronunciation, vocabulary, grammar, and patterns of usage. Researchers studying second-language learning often find it useful to treat the learner’s knowledge of the second language as a sort of language in its own right, what they call “inter-language”.