Approaches to contrast
The notion of contrast has been central to linguistics since Saussure's famous dictum that ‘dans la langue il n'y a que des différences … sans terms positifs’ [‘In a language there are only differences, and no positive terms’] (Saussure 1972 : 166). ‘The sound of a word’, according to Saussure, ‘is not in itself important, but the phonetic contrasts which allow us to distinguish that word from any other’. That is, a phoneme is identified not only by its positive characteristics – for example, the fact that it sounds like [i] – but also by what it is not – that is, by the sounds it contrasts with.
The notion of contrast can be understood at several different levels. At the most basic level, it can refer simply to whether two sounds contrast in a language or not. In English, for example, [i] is different from [i], and these vowel sounds alone are able to differentiate words in the language: sheep [∫Ip], for instance, is different from ship [∫Ip]. This contrast recurs in many other word pairs, such as cheap ∼ chip, seat ∼ sit, seen ∼ sin, meal ∼ mill, reed ∼ rid, and so on. Compare this situation with that obtaining in Israeli Hebrew, which has a single phoneme in the part of the vowel space where English has two. This phoneme, which can be represented as /i/, is pronounced somewhere between English /i/ and /i/ (Chen 1972).