Individual psychology is a locus or node within a larger social system.
More precisely, individual psychologies are particular signaling systems within larger social signaling systems.
It is valuable to see this because general analyses of signaling systems—even those having nothing to do with human psychology—can shed light on human signaling systems, including both individual psychology and many aspects of sociology.
When human psychology is viewed as a signaling system, we can readily see that narcissism is bound to occur because narcissism is fundamentally a simplistic signal system. See Narcissism redefined (yet again) for more.
When human sociology is viewed as a signaling system, we can similarly see that parasitism is bound to occur because the exploitation of one system by another is a fairly simple matter. See Social parasitism in ants and humans for more.
In like manner, we can see that social hierarchies importantly have evolved because they are simple and decently efficient signal (communication) systems.
We can also see why hierarchical system often are overthrown and why they often do not arise in systems where they are not needed. For example, no hierarchy is needed for a transportation system if everyone agrees to the rules. Nor is one especially needed for a language system once the basics have been established. A parasitic group might impose a hierarchy on a language system, but that’s a different animal.
When individual psychology is viewed as a signaling system, we can see that a great deal of what we consider “disordered” or “ill” within that system is fundamentally a problem of the signal system itself and not the “personality” we have mistakenly abstracted out of that system.
Indeed, most of what we think of as personality is nothing more than an individual signal system attempting to conform to its understanding of the larger social system within which it exists. When science is applied to “personality” erroneously conceived, we arrive at the many psychometric tautologies on personality traits we now have. Psychometrics have limited value for describing societies, but are frequently misleading, even damaging, when applied to individuals. In this, they resemble BMI data which originally was used as a marker for the health of whole populations, not individuals, and which can be misleading when applied to individuals.
In contrast, when we view individuals as signaling systems rather than personalities, we can immediately see that these systems can and should be optimized for better communication. Indeed, this is the real job of psychology—optimizing individual signaling systems! Not just treating disorders!