The oppositional theory was originally formulated as a phonological theory by representatives of the Prague School. The method of oppositions has been successfully extended to grammar and semantics. Three main qualitative types of oppositions were established: privative (отрицательная); gradual (постепенная); equipollent (равная по силе).

By the number of contrasted oppositions they were divided into 1) binary, 2) more than binary. The most important for analysis is the binary privative type of opposition. The binary privitive opposition is formed by a contrastive pair of members in which one member is characterized by the presence of a certain differential feature (mark), while the other is characterized by the absence of this feature. The member in which the feature is present is called the marked, or the strong, positive member; the member in which the feature is absent, is called the unmarked, weak, negative member. Example 1: I study (weak member – non-past) – I studied (strong member – past). Example 2: a bird (weak member- non-plurality) – birds (strong member – plurality).

The gradual opposition exists only on semantic level. It’s formed by a contrastive group of members which are distinguished not only by the presence or absence of a feature, but by the degrees of it. Example: the degrees of comparison in adjectives: strong-stronger-strongest.

The equipollent opposition is formed by a contrastive pair or group in which the members are distinguished by different positive features. Example: to be-forms: am – is – are – they are equal in value.

The meaning of the weak member of the privative opposition is more general and abstract as compared with the meaning of the strong member, which is more definite and concrete.

In various contextual conditions one member of the opposition can be used in the position of the other. This phenomenon is called oppositional reduction, or oppositional substitution. E.g.: Tonight we start for London.-the weak member– Present tensereplaced the strong one- the Future tense. Such case is called neutralization of oppositions. E.g.: She is constantly grumbling. – It’s an exaggeration, not a continuous process. Here a strong member is used in the meaning of the weak member for stylistic purposes. This kind of oppositional reduction is called transposition (Blokh, 2000).

The means employed for building up member forms of categorial oppositions are traditionally divided into: 1.synthetical, 2. analytical. So the grammatical forms themselves are classed into synthetical and analytical grammar forms. Synthetical grammar forms are realized by inner morphemic composition of the word. Analytical forms are built by a combination of at least two words, one of which is an auxiliary, and the other – a notional word. Synthetical grammar forms may be:

– Inner-inflectional: goose-geese,

– Outer-inflectional:boy-boys,

– Suppletive: good-better-best, is -was, were-been.

The first type is not productive in Modern Indo-European languages, it is used in English in forms of irregular verbs: keep-kept-kept, forms of singular and plural: man-men.

Suppletivity is not productive either. It is based on the correlation of different roots: be-was, were-been.

Outer-inflectional forms belong to the productive means of affixation. There are quite a few grammar suffixes which are used to build up the number and case forms of the noun; the person, number, tense, participial and gerundial forms of the verb; forms of comparison of adjectives and adverbs.

The analytical grammar forms are traditionally considered to be a combination of an auxiliary and a basic word, and it’s one of the most typical ways of form-building.