Personality Type: An Owner's Manual

Type Is a Vocabulary for Unlived Life, Not a Label for Lived Behavior

Lenore Thomson opens Personality Type with a Chinese wisdom story about a captive woman who cannot choose a door that leads to a garden that does not yet exist. She can only negate: “This door is not the door that leads to the garden.” The parable is not decorative. It is the book’s thesis in miniature. Thomson contends that psychological type, properly understood, is not a system for categorizing what people already do. It is a vocabulary for recognizing what they have sacrificed — the raw possibility that “comes to our awareness only when we realize that something is missing.” This is a sharp departure from the dominant application of the Myers-Briggs Type Indicator in corporate settings, where type functions as a sorting mechanism for team composition and career placement. Thomson is explicit: “Type is not an internal tape loop that irrevocably determines people’s options.” She reclaims the Jungian foundation that Isabel Briggs Myers built upon but that the consulting industry largely flattened. The real utility of type, for Thomson, lies in its capacity to name the restlessness that emerges when a personality has consolidated too thoroughly around its preferred functions, leaving other capacities to wither. This aligns her more closely with Jung’s late-career writings on individuation than with the psychometric tradition that his typology spawned. Where Naomi Quenk’s Was That Really Me? focuses on the inferior function as it erupts under stress — the “grip” experience — Thomson is interested in the broader developmental arc: how the ego builds its house, and why the foundation eventually cracks.

The Neurological Turn Dissolves a Century of Cultural Mythology

Thomson’s most original contribution is her integration of brain lateralization research into Jungian function theory. She reports a finding that remains underappreciated even among type practitioners: introverted and extraverted versions of the same function activate on opposite hemispheres. Extraverted Thinking and Extraverted Feeling are predominantly left-hemisphere operations; their introverted counterparts light up the right hemisphere. The reverse holds for the perceiving functions. This is not a footnote. It demolishes the popular equation of Thinking with “left-brain logic” and Feeling with “right-brain emotion.” As Thomson puts it, “these skills characterize only Extraverted Thinking, a left-brain, linguistic manner of reasoning. The right brain also Thinks, from an Introverted standpoint, by way of visual, tactile, or spatial logic.” The implication ripples through the entire system. Introverted Feeling is not sentimentality; it is a right-brain evaluative process that operates through subjective, image-laden apprehension of value. Extraverted Intuition is right-hemispheric and holistic; Introverted Intuition is left-hemispheric and language-oriented, “encouraging us to move beyond the boundaries of accepted terms and explanations.” This neurological grounding also explains why the dominant and secondary functions cooperate so readily — they share a hemisphere — and why the inferior function is experienced as alien: it demands processing in the brain’s unaccustomed territory. Thomson’s lateralization argument gives empirical teeth to the experiential phenomenon Quenk catalogs in her inferior-function research. The “grip” is not just a psychological event; it is, Thomson suggests, a neurological border crossing.

The Inferior Function as Evolutionary Engine, Not Diagnostic Category

Thomson’s treatment of the inferior function is where her depth-psychological commitments are most visible. She frames typological imbalance not as deficit but as the psyche’s own self-correcting mechanism: “the subversive efforts of our least-developed function are probably our best safeguard against complacency and automatic behavior.” The inferior function operates like the “alien hand” of split-brain patients — it literally interferes with the dominant hand’s goals. But this interference is purposeful. Thomson draws on mythological parallels — Odin pawning an eye for wisdom, Eve gaining discrimination at the cost of paradise — to position the sacrifice of functional wholeness as a precondition for consciousness itself. “By setting ourselves a direction, we surrender a great deal of our generic potential, but in return, we develop what Jung called differentiated strengths.” The paradox is that successful differentiation produces its own crisis: the functions left behind “begin to claim our attention” with increasing urgency. This maps directly onto the Jungian concept of enantiodromia — the tendency of any psychological extreme to generate its opposite — and onto Murray Stein’s account of the midlife transition in In Midlife, where the first-half identity must dissolve to permit second-half integration. Thomson does not use Stein’s terminology, but the structural parallel is exact. Where Quenk provides the phenomenology of inferior-function eruption — what it looks like when an ENTP’s Introverted Sensation seizes control — Thomson provides the teleology. The eruption is not just stress response; it is developmental demand.

Type Development as Conscious Struggle, Not Balanced Equilibrium

Thomson is unambiguous that typological health is not balance. “In the realm of nature, perfect balance is not a good thing. A physical system reaches equilibrium when it has lost its energy and can no longer change.” Close scores on a type inventory do not indicate integration; they indicate insufficient differentiation — a self that has not yet committed to its own direction. This is a direct challenge to the popular self-help reading of Jungian typology, which often implies that the goal is to develop all functions equally. Thomson insists that the point is the struggle between preferred and non-preferred functions, which generates the psychic energy necessary for growth. The connection to Jung’s original formulation in Psychological Types is critical here: Jung argued that one-sidedness is not a defect to be corrected but the necessary condition for consciousness, which emerges precisely through differentiation rather than homogeneity. Thomson extends this by noting that traditions of contemplative practice restrict interior seeking to those who have already achieved “tangible success in matters of work and love” — a pointed reminder that transcendence without ego-development is inflation, not individuation.

For a reader encountering depth psychology through the doorway of personality type, Thomson’s book does something no other typology text accomplishes. It refuses to let type become static identity. By anchoring the function-attitudes in neurological research, mythological patterns, and the developmental logic of individuation, it transforms what most people encounter as a workplace parlor game into a genuine instrument of self-knowledge — one that reveals not who you are, but what in you is still demanding to be born.