I like to think that poets have an intuitive and practiced sense of how many functions language has in daily life. Intellectually we tend to notice only the “representational” function—the way each word has a meaning (or several) and what that meaning is. But we use language not merely to communicate the meaning that the dictionary confirms for us. There’s a lot more going on in the simplest of human communication than that. Perhaps most of all in the simplest.
But the academic study of literary language tends to be confined mostly to the representational function, and almost never do I see a critical description or analysis of poetry that goes into the language functions that affect us at deeper, more intuitive levels. For a while, peaking in the 1980s and only slowly trailing off after that, it was hard to find a scholar in the field of literary studies who believed that language had any other function than the representational. Hence the strong attitudes of that time in many academics against what they call “the aesthetic,” meaning almost any formal aspect of poetry at all, from tiny phonetic figures to big structures.
The acquisition of language by children has been studied deeply, though, and here we can find a refreshing breadth of responsiveness to the different things we do with language—which means the different ways we make and communicate our meaning, and that in turn means: all the possibilities of meaning making that can be found in poetry.
Here’s my favorite example, although it is probably rather dated by now:
“The linguist Michael Halliday observed his young son during the period when his vocalizations were assuming consistent phonological form and when he began to exhibit clearly an intention to communicate by means of these forms. Halliday was able to distinguish seven different functions, or uses, of his son’s talk, which he took to be models of the child’s conception of what talk is for. The first notion to emerge is that of talk as  instrumental, a means of satisfying wants or needs. Another function is  regulatory: the child discovers that others seek to control him by talking and that he can also control the behavior of others. The child also senses that one can establish and maintain contact with others by talking; he recognizes  the interactional function. The child also expresses his individuality in talking; he asserts himself and his own sense of agency, for talking is a field of action in which he can make choices and take some responsibility. Thus talking has  a personal function, as well.  The heuristic, or learning, function, is exemplified in the perennial questions ‘why?’ and ‘what’s that?’; the child finds that he can use talk to learn about and describe his world. And talking serves  the imaginative function of pretend, which may overlap with an aesthetic function (although Halliday does not dwell on this possibility) as the child realizes that he can create images and pleasurable effects by talking. Finally, the perhaps the latest use of talk to appear, is the representational function, or talking to inform. Adults, when they think about language, regard it as a means of expressing propositions or as a means of conveying information. They view this as the primary function of talk, but it is hardly the dominant use for the child.” (Catherine Garvey, Children’s Talk, 1984, emphasis added)
The linguist David Crystal has analyzed the functions of language in a different, emphasizing communicative effect, whatever the intention may be.
(1) expressing emotion
(2) expressing rapport
(3) expressing sound
(5) controlling reality
(6) recording [and preserving, I would add] facts
(7) expressing thought processes
(8) expressing identity
…he also situates the use of language in the context of technology. Crystal is emphatic that one must keep oneself aware—when studying language itself, or even when thinking about it informally, as a lay person not a linguistic—of the diversity of language functions. (This list is from his book How Language Works.)