The four themes in Part I are concerned with the internal organisation of language. Themes A and B explore the ways in which we use language to convey meaning, whereas C and D are more concerned with the way in which we draw upon the resources of the language to construct what we want to say. Themes A and B focus upon the messages that we intend to convey, while themes C and D concentrate upon the utterances that we make.
One problem in talking about language is that our everyday vocabulary is not very helpful when it comes to making some of the basic distinctions that are necessary. Thus, we need to be able to distinguish between the content and the form of language. Message refers to everything that a speaker or writer intends to convey by his words and also to everything that is understood by the person who hears him or reads what lie writes. Utterance, on the other hand, refers to the actual pattern of sounds or symbols that lie uses to convey the message.
Another problem in English is that we have very few words which refer both to speech and to writing, whereas many things that we want to say about language in use refer to both. Messages and utterances are a case in point. Messages can be spoken or written, heard or read, and whatever is spoken or written, heard or read, is an utterance. Equally, we have no common words which refer to the fact that people both speak and hear, write and read. In fact, our everyday language assumes that we always want to talk about language from the point of view of the person who is speaking or writing. This volume therefore has to talk about speakers and hearers, readers and writers, in order to show that language in use is always a two-way process.
Themes A and B, then, are concerned with the nature and function of messages, whether these are spoken or written. Theme A explores the way in which messages convey information, while theme B is concerned with messages as the vehicle for expression. The distinction between information and expression is similar to that between message and utterance; all messages must be uttered, and all utterances carry a message, but it helps to focus on one aspect of our using language at a time. In the same way, all messages contain information and express attitudes or feelings, but it is easier to see that this is so if we can focus upon each in turn. Both theme A and theme B explore what happens when we language our meaning for others. In theme A, the focus is upon what happens when we want to convey information: in theme B, the focus is upon what happens when we want to express our feelings. In both cases, we can examine these questions in relation to what is spoken and to what is written.
Themes C and D stand in a rather different relationship to each other. Theme C is concerned with the medium which we use to convey an utterance, whether speech or writing, while theme D focuses upon the internal organisation of the utterance. That is to say, theme C answers the question: how do we send messages? Theme D answers the parallel question: how do we put together an utterance to convey the message that we want to use?
Theme C looks at the nature of speech. and at the crucial relationship between the patterns ofspeech and the writing system which is derived from them. It stresses the fact that speech is primary and examines how lie writing system compensates for not having the resources which intonation provides in speech. These resources have to be represented by a small stock of conventional signs, or by a skilful rephrasing of the message.
An important function of Language in Use is to create conditions in which some widely held popular views about language can be subject to scrutiny. Theme C contributes to this by showing that writing derives from speech; that speech has its own organisation; and that to judge speech as though it were merely an inadequate representation of what is written is to misconceive the nature of speech and its relationship to writing.
Theme D focuses upon the structure of the utterance. It is concerned with the form which we give to messages, but it does not suggest a detailed programme of grammatical analysis. The emphasis is upon the degree to which language functions successfully, because its form is very tightly organised and allows only a limited number of combinations at any particular point in an utterance. While messages are infinitely variable, the forms which they can be given in conveying them as utterances are strictly limited. The underlying premise of the theme is that language could not function at all unless it were in many ways predictable, that our freedom to 'say what we like' is limited by the formal organisation of language in order to enable us to say anything at all.