The unified self is a convenient fiction. In practice, identity is always multiple — we are different people with our parents, our partners, our colleagues, our strangers. But these sub-selves are usually integrated: they share memories, values, and a sense of continuity. Identity fragmentation occurs when this integration dissolves.
The most dramatic form is Dissociative Identity Disorder (formerly Multiple Personality Disorder), in which the self fragments into distinct "alters" with separate memories, behaviours, and even physiological characteristics. The condition is controversial — some clinicians doubt its existence; others consider it a genuine response to severe childhood trauma. What is not controversial is that the self can dissolve into parts that do not recognise each other.
Less dramatic but more common is the fragmentation produced by modern life. Social media encourages the maintenance of multiple public selves — the professional self on LinkedIn, the intimate self on Instagram, the argumentative self on Twitter. These selves are curated for different audiences and may contradict each other. The person who is kind in person and cruel online is not necessarily a hypocrite; they may simply be different people in different contexts.
Fragmentation is not necessarily pathological. Some degree of multiplicity is adaptive. The problem arises when the fragments lose contact with each other — when the self dissolves into parts that share no common ground. Integration is the work of therapy, of reflection, of simply paying attention. The self is not a given; it is a project, and it requires maintenance.
In Fiction
Philip K. Dick's A Scanner Darkly (1977) is a study in identity fragmentation under the pressure of drugs and surveillance. The protagonist, an undercover narcotics agent, is assigned to investigate himself. The self splits, then dissolves. "I saw Death rising from the earth," the novel ends, quoting the Bible, "and the dead walked again." The dissolution is complete; what walks afterward is not the same person.