The Flawed Binary Logic of MBTI Is Stunting Your Career Growth

The Binary That Built a Box: How a 1940s Mother-Daughter Project Still Shapes Your Career By Leah Morgan Why does a personality test designed to place women in wartime factory jobs still show up in corporate retreats, career coaching, and team-building exercises eighty years later? The answer has less to do with psychological depth than with a pragmatic choice made in 1943: to turn fluid human tendencies into four clean either/or switches. Katharine Cook Briggs and her daughter Isabel Briggs Myers were not trying to build a lifelong identity system. They were responding to a labor shortage. With men deployed overseas, factories needed to match a new workforce—thousands of women—to roles they could perform well and tolerate. The mother-daughter team, steeped in Carl Jung’s Psychological Types, saw an opportunity to apply his ideas to a practical sorting problem. But Jung’s framework was anything but binary. He described introversion and extraversion as coexisting attitudes, thinking and feeling as complementary functions that every person uses in varying degrees. “Every individual is an exception to the rule,” he wrote—a warning that the categories were starting points, not boxes. Briggs and Myers, however, needed a tool that a factory supervisor could use without a psychology degree. They collapsed Jung’s nuanced spectrum into four dichotomies: Extraversion vs. Introversion, Sensing vs. Intuition, Thinking vs. Feeling, Judging vs. Perceiving. Each person would land on one side or the other, producing a four-letter type. The simplification was deliberate and practical—a matching algorithm on paper, long before algorithms became a buzzword. It worked well enough for its original purpose: it gave supervisors a plausible way to guess whether someone might thrive on an assembly line or in a clerical role. The trouble started when the test outgrew its wartime roots. After the war, the MBTI was picked up by educational institutions and, later, by a booming corporate culture hungry for tools to manage teams and develop leaders. The binary structure, so useful for quick sorting, began to harden into an identity. People started introducing themselves with their four letters. Job interviews incorporated type language. Career counselors advised clients to “find a role that fits your type,” as if the sixteen categories were destinies rather than rough sketches. This is where the historical accident bites hardest. Because the test forces a forced-choice answer on every question—you’re either a thinker or a feeler, never a bit of both—it erases the messy middle that Jung insisted was the norm. A person who scores 51% on the Thinking side of the scale gets the same “T” label as someone who scores 95%. Over time, that label can become a self-fulfilling story: “I’m a Thinker, so I’m not good with people,” or “I’m a Feeler, so I shouldn’t go into data science.” The test’s design, born from the practical need to simplify, creates a box that feels real even when the underlying data are fuzzy. What makes this more than a historical curiosity is how the MBTI’s binary logic has seeped into modern career thinking. Many popular workplace assessments—whether they sort people into colors, animals, or archetypes—still rely on categorical types rather than continuous traits. The appeal is understandable: types give us a shared vocabulary and a sense of clarity. But the clarity is often false. Decades of research in personality psychology have converged on a different model, the Big Five, which measures traits along continuous dimensions. Openness, conscientiousness, extraversion, agreeableness, and neuroticism aren’t boxes you’re in or out of; they’re spectrums where most people cluster in the middle. When a manager uses a type-based tool to make hiring or promotion decisions, they’re essentially using a 1940s sorting algorithm on a 21st-century workforce. None of this means the MBTI is useless. It can open conversations about work styles and preferences, and it can help people notice patterns in how they approach problems. But its power should stop there. The moment a type label becomes a career cage—when someone says “I can’t lead that project because I’m an introvert” or “I’m not creative because I’m a Sensor”—the tool is being misused in exactly the way its inventors never intended. Briggs and Myers wanted to help women find jobs, not to define their potential for a lifetime. So the next time a workshop hands you a set of four letters, remember the factory floors of 1943. The categories are tools—useful for a quick sketch, dangerous as a permanent address. The real you is the messy, continuous, exception-to-the-rule person that Jung was talking about all along.