Chapter 6. The concept of a tie makes it possible to analyse a text in terms of its cohesive properties, and give a systematic account of its patterns of texture. Some specimen <llnalyses are given in Chapter 8. Various types of question can he investigated in this way, for example concerning the difference be- tween speech and writing, the relationship between cohesion and the organization of written texts into sentences and paragraphs, and the pos- sible differences among different genres and different author:s in the num- bers and kinds of tie they typically employ. The different kinds of cohesive tie provide the main chapter divisions of the book. They are: reference, substitution, ellipsis. conjunction, and lexical cohesion. A preliminary definition of these categories is given later in the Introduction (1.2.4); each of these -concepts is then discussed more fully in the chapter in question. 1.1.4 OJhesion The concept of cohesion is a semantic one; it refers to rdations of meaning that exist within the text. and tha.t define it as a text. Cohesion occurs where the INTRllPB:RTATION of some element in the discourse is dependent on that of another. The one PRESUPPOSES the other. in the sense that it cannot be effectively decoded except by recourse to it. When this happens. a re1ation of cohesion is set up, and the two de- ments, the presupposing and the presupposed. are thereby at least poten- tially integrated into a teXt. Tills is another way of approaching the notion of a tie. To return to example [I: I]. the word them presupposes for its. interpretation something other than itsd£ This requirement is met by the six cooklng applu in the preceding sentence. The presupposition, and the fact that it is resolved. provide cohesion between the two sentences, and in so doing create text . .& another example. consider the old piece of schoolboy humour: [" s] Time !lies. -You can•t; they fly too quickly.
I.J THE CONCEPT OP COHESION j The first sentence gives no indication of not being a complete text; in fact it us:uaUy is. and the humour lies in the misinterpretation that is required. if the presupposition fi-om the second sentence is to be satisfied. Here, inci- dentally. the cohesion is expressed in no less than three ties: the elliptical form you can't (Chapter .;), the reference item they (Chapter 2) and the lexi- cal repetition fly (Chapter 6). Cohesion is part of the system of a language. The potential for cohesion Jics in the systematic resources of reference. ellipsis and so on that are built into the language itsd( The actualization of cohesion in any given in- stance, however~ depends not merely on the selection of some option from within these resources, but also on the presence of some other element which resolves the presupposition that this sets up. It is obvious that the sekaion of the word apples has no cohesive force hy itsdf; a cohesive rela- tion is set up only ifthesameword,or a word rdated to it suchas.fruit(see