Mechanism of Change. Role of Synchronic Variation
From comparing the state of linguistic units before and after a change one can determine the nature of the change, define its type and direction; but in order to understand how the change came about one must also trace the process or mechanism of the change.
A linguistic change begins with synchronic variation. Alongside the existing language units — words, forms, affixes, pronunciations, spellings, syntactic constructions — there spring up new units. They may be similar in meaning but slightly different in form, stylistic connotations, social values, distribution in language space, etc. In the same way new meanings may arise in the existing words or forms in addition to their main meanings. Both kinds of variation — formal and semantic — supply the raw material for impending changes.
Synchronic variation is to be found in every language at every stage of its history. It is caused by two main factors: functional differentiation of language and tendencies of historical development.
Language is a heterogeneous system of immeasurable complexity; it functions in various forms as a group of mutually intelligible overlapping speech varieties. The range of synchronic variation largely depends on the distinction of the main functional varieties and also on the variable use of the language in different conditions of communication, in various social groups and in individual forms of speech. Synchronic differences between the varieties of language may consist of specific items not to be found in other varieties, or in the different use of the same items, which may seem slightly unusual and yet quite intelligible to the speakers of other varieties.
Synchronic variation reveals the tendencies of historical development and is produced by those tendencies. New features, which appear as instances of synchronic variation, represent dynamics in synchrony and arise in conformity with productive historical trends.
Variation supplies material for linguistic change and also provides conditions for its realisation.
At every period of history, language offers a wide choice of expressive means to the speaker. From this stock — consciously or unconsciously — the speaker selects forms of expression suitable in the given situation; in making this choice he observes the speech habits of his social group or employs forms of expression current in other varieties of the language; sometimes he creates new expressive means — forms, words, phrases — in accordance with the productive historical tendencies. Old and new forms begin to be used indiscriminately, in free variation, which may lead to a change in their relative frequencies and finally to the substitution of one for another. Thus synchronic variation ensures a gradual imperceptible realisation of the change. If the co-existing competing units lose all differences, one rival will die out and the other will occupy its place, for only in rare cases can genuine free variation exist for long (that is, co-existence of absolute equivalents). If the differences between parallel means of expression persist and are accentuated, both rivals will survive as distinct units.