Splitting

In plain words

Splitting is losing the middle. A friend is wonderful until the first disappointment, and then they are the enemy. A project is perfect, then worthless. The person is not exaggerating on purpose; holding good and bad together in the same person feels unbearable, so one half is put away.

Where the idea comes from

The idea has several roots. Hippolyte Taine described a split of the ego in 1878 and Pierre Janet a splitting of consciousness in 1889. Freud used Spaltung for a division of consciousness arising from inner conflict, and in his late Outline of Psycho-Analysis (written 1938, published 1940) described the ego effecting "a cleavage or division of itself". The object-relations tradition gave the term its modern use. Ronald Fairbairn (1952) described splitting as an infant's inability to combine the good and frustrating aspects of its parents into one object; Melanie Klein described splitting of the object into good and bad in what she called the paranoid-schizoid position. Otto Kernberg treated the resolution of splitting as a developmental task and linked its failure to borderline pathology. See object relations.

In Vaillant's ranking of defence mechanisms, splitting is an immature defence.

How it shows up

Look for idealisation followed by devaluation, as the DSM-IV-TR puts it, in "extremes" between people. In everyday life it appears in the way a person talks about a boss, a therapist, a parent or themselves across weeks: first without fault, later without merit. The same phrase may be applied to the self ("I am a failure").

Oneli, the AI agent on TwentyThird, follows how a member describes the same person over time, because a swing from one pole to the other is information. It does not diagnose and does not label anyone borderline. If a member feels trapped in this pattern, the person to take it to is a clinician.

What it is not

It is not a diagnosis, and it is not limited to borderline personality disorder: the Wikipedia article says it is also described in narcissistic personality disorder, depression and other conditions, with differing meanings. The concept is used in several senses, and Blass (2015) argues those differences matter. Much of the support is theoretical or clinical; empirical studies exist (for example on depression and on self-esteem instability) but are mixed in scope.