The term “complexity” derives from the Latin “complecti” (to embrace, to include, to cover, to entwine) and “complexus” (embrace, aggregation of parts).
Nowadays sociology (as well as other disciplines) are fully involved in this concept.
The notion of social complexity is not new and it has characterised many theories (e.g. systems, structural functionalism, social action) and scientists (e.g. Spencer, Pareto, Parsons, Luhman). What is new is a broad change in the theory’s horizon that happened as a catalyst combination between scientists as A. Einstein, I. Prigogine, E. Morin, G. Bateson, F. J. Varela, H. von Foerster. They underlined how the rational, linear, mechanistic conceptions were limited and unilateral.
Terms such as reason, order, symmetry, certainty, measurability, harmony, equilibrium, homogeneity, law, truth, objectivity, rationality, regularity, predictability were strongly questioned. On the contrary the complexity theories affirm that life, humanity, evolution, change, knowledge, etc. originate from and go hand in hand with disorder, chaos, perturbation, dissymetries, instability, non-equilibrium, flows, turbulence, non-linearity, marginality, uncertainty, relativity, dis-harmony, fractalism, imponderability, etc.
This is more true nowadays when the overall interdependence (globalisation) acts in such a way that local actions have very broad consequences, both in distance (space), time and dimensions.
Globalisation is the coming together of different, also unique, individual and fragmented initiatives; therefore only a connecting strategic thinking (holism) can comply with complexity, respecting what is diverse (and divergent), the multidimensional facets of situation and problem (fractal and hologram) and operating on their interdependencies.
In fact the whole is in the part as well as each part is in the whole.
As Pascal said some centuries ago: since all things are causes and effects, mediate and immediate, connected and separated at the same time, it is impossible to know a part without knowing the whole, as well as vice versa.
This means to think globally and to act locally with its reverse, to act globally and to think locally. As Pascal wrote: the parts of the world are all related and linked to one another.