Grammar as a phenomenon – a subsystem of language as a linguistic discipline

The binary privative opposition is formed by a contrastive pair of members in which one member is characterised by the presence of a certain differential feature ("mark"), while the other member is characterised by the absence of this feature. The member in which the feature is present is called the "marked", or "strong", or "positive" member, and is commonly designated by the symbol + (plus); the member in which the feature is absent is called the "unmarked", or "weak", or "negative" member, and is commonly designated by the symbol — (minus).
The equipollent opposition is formed by a contrastive pair or group in which the members are distinguished by different positive features.
For instance, the phonemes [m] and [b], both bilabial consonants, form an equipollent opposition, [m] being sonorous nazalised, [b ] being plosive.
The gradual opposition is formed by a contrastive group of members which are distinguished not by the presence or аbsenсе of a feature, but by the degree of it.
For instance, the front vowels [i:—i—e—ae] form a quaternary gradual opposition, since they are differentiated by the degree of their openness (their length, as is known, is' also relevant, as well as some other individualising properties, but these factors do not spoil the gradual opposition as such).

In various contextual conditions, one member of an opposition can be used in the position of the other, counter-member. This phenomenon should be treated under the heading of "oppositional reduction" or "oppositional substitution".

Oppositional reduction
The opposition looses its formal distinctive force

1. 
   Neutralization – the weak member acquires the meaning of a strong member
   

Ex. We leave for Moscow tomorrow.( the opposition “present - future” is reduced)
+Bloh Man conquers nature.
The noun man in the quoted sentence is used in the singular, but it is quite clear that it stands not for an individual person, but for people in general, for the idea of "mankind". In other words, the noun is used generically, it implies the class of denoted objects as a whole. Thus, in the oppositional light, here the weak member of the categorial opposition of number has replaced the strong member.

2. Transposition – one of the members of the opposition (usually a strong one) is used in context uncommon for it and stands in contradiction with its regular gram. meaning He is always complaining.

Categories
Opposition of forms
Types of opposition
Meanings of the members
Meaning of the category
Peculiarities