For Bakhtin, language is dialogic, meaning that no one person or group owns it; the meanings of words instead develop in the context of dialogues between different people. For Bakhtin, the basic unit of meaning in language is the word or what he calls the utterance (rather than the sentence). The term utterance implies that a word gains meaning as it is spoken, in the context of listening and responding to other people's utterances, which themselves are shaped by dialogue and context. Thus, language is what he terms polyphonic: it has many overlapping layers with meanings that can be derived from utterances between different people of various classes, genders and points of view. As Bakhtin put it in the Dialogic Imagination: "The word lives, as it were, on the boundary between its own context and another, alien, context." Bakhtin's work, which focuses on the novel, is important because it emphasizes language as inherently social, contextual and evolving. Language does not exist in a rarified academic ether but rather in the mess of ordinary life and thus is open to a variety of interpretations. 

Bakhtin treats language as both organic and social. This means, basically, that the meanings we ascribe to language, or the utterances that make up language, are developed through discourse, or dialogic interaction (in other words, speaking and communicating) with others. So esentially, on the face of it, Bakhtin's theory would suggest that language is entirely relativistic, that we assign whatever meanings we want to language, and that we can't be sure that when we use language, that we are communicating the ideas that we want to communicate. However, the desire, or need to be understood drives language toward mutually agreed-upon meanings, which are communicated, from the point of view of literature, in agreed-upon forms, like the novel or the classical Greek forms of "epic, lyric, and tragedy." Even these forms, however, were subject to subversion and "travestying forms." The point is that communication is not inhibited a priori by structures or by arbitrary rules. These conventions developed out of specific circumstances, through dialogic communication, which is always a negotiated process.

Assess how Bakhtin treats language.

I tend to think that any discussion of Bakhtin is going to be complex and intricate.  In true Bakhtin form, there is little that is simple and direct.  Rather, much of his thinking is divergent and nuanced.  His view of language fits this classification.  For Bakhtin, language is the result of a polyphonic state of being in the world.  There can be little chance of pure isolation, or the ability to fully construct a verbal means of recognition without a sense of interdependence on others.  For Bakhtin, language and linguistic construction is the result of polyphony.  Bakhtin's analysis of Dostoyevsky's work demonstrates this.  For Bakhtin, Dostoyevsky's work reveals characters who demonstrate a sense of "unfinalizability," reflecting the fluid and dynamic nature of language and the state of being associated with it.  Language becomes a reflection of individual being, intersecting others' and reflecting a constant state of interdependence and independence.  Language is not something that is static that can be overcome and pue of individual construction.  Rather, it is one that feeds into others.  In this, the polyphony of language becomes evident in Bakhtin's world.