Editorial for Special Issue: Complexity within Cognitive Behaviour Therapy

As therapists we frequently use and hear the term ‘complexity’ in relation to clients, situations and settings. Although we may assume there is a shared understanding of what is meant by complexity, is this true? Do we really know what we mean by describing someone, or something, as complex? If we define complexity as ‘consisting of many different and connected parts, not easy to analyse or understand’ (Oxford English Dictionary, 2017), then we are probably describing intersections and interactions between different elements that can influence each other. Interestingly, the origin of the term derives from the Latin past participle plexus, meaning braided or entwined, which captures neatly the sense of the term ‘complex’ as meaning literally braided together. The breadth of this definition therefore may help to account for the diversity of the ways in which the term complexity is used in clinical settings. Continuing with the idea of the plait or braid, it also gives a sense of the number of threads or strands that could be incorporated within such a system. Complexity can derive from any source, and can interact with any part, so it can derive from the patient, the therapist, the therapeutic relationship or the healthcare setting; and each of these may interact with one or more parts. So from any source, complexity can affect processes and outcomes of care.