Updated: Nov 24, 2020
People with borderline personality disorder have two distinct, simultaneously operative psychological ‘operating systems.’ One of these is appropriately adult and sane. The other is infantile in nature. One part of the BPD person’s mind remained ‘stuck’ or ‘fixated’ at an early phase of life, usually very early childhood. The other part advanced to maturity. The part that remained stuck in early childhood did so because of a trauma, usually sexual molestation. People with BPD oscillate between these two psychological integrations. In other words, at one time, the adult operating system will be operative, while at other times the other system will be operative.
People with BPD may instantaneously and frequently shift oscillate between these two modalities. This makes them appear to be lying or ‘playing games’, when in fact they are shifting between two distinct and incongruent world views. People with BDP may be extremely intelligent and intellectually developed; and during their lucid moments, they may seem—and in fact be---utterly sane and also utterly decent. For this reason, when they shift into their infantile mode, during which they are accusatory, narcissistic, and oftentimes violent, others assume that all along they were simply lying and were simply psychopaths who were simply wearing a mask of sanity and decency.
This is the wrong inference to make. People with BPD are not psychopaths. When their infantile side predominates, they act in the same entitled, limitlessly self-servingly narcissistic way as psychopaths. But they are acting that way because they have an infantile, and therefore correspondingly narcissistic, side, which, at that moment, is the operative side. Whereas the psychopath is simply a phony, who sometimes puts on a mask of sanity and decency, the BPD person is genuinely two-sided, one of these sides being sane and decent, the other being infantile and tyrannical, each side being genuine and therefore neither being a mask.
An important fact about BPD is that their preferred psychological defense is not repression but is rather splitting. In fact, the BPD personality-structure is itself the result of splitting. Repression is about having a single psychological architecture—a single operating system---and, when one has a conceit (a feeling or drive) that is incompatible with that architecture---shoving it into the abyss of the unconscious, which is where the psychological vestiges of infancy are deposited. Splitting is about not having to repress for the reason that one shifts between one’s adult side and one’s infantile side. Whereas the normal (non-BPD) person’s psyche keeps its infantilism in the abyss of the unconscious, this being where it shoves the various urges that it has that are consistent with that operating system, the BPD person’s psyche does not repress these infantilisms, but rather keeps them in a concurrently operative sphere of mental activity, which sometimes becomes the dominant one.
So the essence of borderline personality disorder is that splitting—this being the separation of the psyche into two distinct operating systems, neither having complete dominance over the other but one of which absorbs the subject’s various infantilisms and other psychological ‘discards’---takes the place of repression—this being the condition of depositing such discards into an unconscious that is subordinate to a fundamentally non-infantile psychological operating system.
The BPD-person often behaves psychopathically. And there is indeed a pronounced streak of psychopathy within this person. But there is a difference between this streak of psychopathy, on the one hand, and full-blown psychopathy, on the other. When the psychopath is acting non-psychopathically, that is indeed because he is just acting. By contrast, when the BPD person acts non-psychopathically, that is because she is being true to one side of her personality. And when she acts psychopathically, that isn’t because the mask of decency and sanity has fallen; it is because she is regressing, with the consequence that her infantile side is dominating. By contrast, when the psychopath acts psychopathically, it is because the mask has fallen and it is not because he is regressing.