SUMMARY
The article advances linguistic synergetics as a novel research methodology by focusing on applicability of synergetic principles to language development studies. Synergetics is a name for the science of complexity that deals with principles of emergence, self-organisation and self-regulation of complex systems. From the perspective of the synergetic approach, a human language is considered an open, dynamic, non-linear, self-organizing system with all its hierarchical subsystems and elements coherently interconnected and controlled by governing parameters. The latter are considered to be principles of grammatical structure imposing constraints on the range of structural variation permitted in a given language. Any human language, as a synergetic system, has its own set of parameters to characterize peculiarities of its structural organization. It is parameters that highlight grammatical differences between languages. From this angle language development is understood as a change of the parameter pattern of a given language system, which causes the latter to self-organize into a new state. It is assumed that at any given moment the system of a language has its own parameter pattern. Any change within this pattern is but a signal of changes of the whole synergetic system. The article focuses on the following four parameters peculiar to Old English, namely: The null subject parameter, The head directionality parameter, The reflexive domain parameter, and The question movement parameter. The article shows that the typological shift of English is based on the mechanism of changes within the parameter pattern of the language. As a result, the Old English synthetic language became the Modern English analytical language. A close examination of historical dynamics of English within its different language levels indicates that language never changes chaotically but has an underlying order determined by certain grammatical parameters of the language system. Mechanisms of self-organization of a complex system lie in the changes within its parameters. By contrast, the structural stability of the language is provided by stability of a great number of control parameters of the language mega-system.