Order parameter
The quantity that describes the behaviour of the whole and that, in turn, orders the parts.
An order parameter is a quantity or concept that allows the global behaviour of a system with many components or subsystems to be captured in a single measure. Even when the individual parts each seem to go their own way, the order parameter describes the pattern they form together.
The notion comes from Hermann Haken's synergetics. Characteristically, it works in two directions. On the one hand, the order parameter arises from the interaction among the many parts: it emerges from below. On the other, once it has arisen, it begins to constrain and steer the behaviour of those same parts. Haken spoke of enslaving: the components are, as it were, taken into service by the pattern they have themselves brought forth. Between the small and the large a circular causality thus arises, working from below and from above at the same time.
In psychotherapy
In the work of Günter Schiepek, the order parameter of a therapeutic process is not a separate measurement but a pattern: an interplay of complaints, meanings, relationships and behaviour that, taken as a whole, has a direction. In his view, such a pattern can be recognised by the coherence it shows over time. Mood, self-image, sleep and activity then do not move independently of one another, but as aspects of one underlying order.
The practical value is that, by following the order parameter, attention is directed not only at isolated symptoms but at the pattern that connects them. When the order parameter changes, the system shifts as a whole, sometimes gradually and sometimes in a leap. Put cautiously, the concept thus offers a language for something clinicians often sense intuitively: that beneath the multitude of complaints a single coherent movement may be hidden.