Denis Diderot

The Encyclopédie was, at its core, an Ne project: the conviction that all of human knowledge could be mapped in a single structure and that exposing the connections between fields would itself be transformative. Diderot's cross-references —pointing readers from theology to philosophy to natural science and back, often with subversive intent—were Ne thinking made institutional. He was not cataloguing knowledge; he was showing how ideas undermine and illuminate one another.

His literary work displays the same quality. Rameau's Nephew, written over decades and never published in his lifetime, pits a rational philosopher against the brilliant, amoral nephew of the composer Rameau—a figure so sharp he is more compelling than the philosopher himself. The text refuses resolution; Ne finds it more interesting to map the territory of a problem than to settle it. Diderot was drawn to ideas that resisted closure—free will and determinism in Jacques the Fatalist, mind and matter in D'Alembert's Dream—because irresolvability was where the thinking lived.

His Letter on the Blind (1749), speculating about whether morality could exist without vision, got him imprisoned at Vincennes for four months—the authorities recognized its materialism as theological provocation wrapped in philosophical puzzle. Diderot kept producing these puzzles because Ne cannot stop finding them.

What distinguished Diderot from the other great ENPs of his circle was auxiliary Fi—a moral seriousness that made intellectual commitments feel like ethical obligations. He did not oppose slavery because it was inconsistent with natural law; he opposed it because it was wrong. His contributions to the abbé Raynal's Histoire des deux Indes (1780) contain some of the most passionate anti-colonial writing of the century—read not as polemic but as personal offense, quite different from Voltaire's cooler distance.

The letters to Sophie Volland are the purest window into this Fi. Diderot wrote to her thousands of times over nearly thirty years, remarkable not for philosophical content but for emotional texture: the minute registrations of mood, the way a dinner party or a piece of music could open him entirely to feeling. Fi does not perform feeling; it inhabits it—and these letters, unpublished in his lifetime, are among the most honest prose of the century.

The artisans and craftsmen who contributed to the Encyclopédie—glassmakers, weavers, locksmiths whose expertise Diderot documented with meticulous respect—were not abstractions to him. He believed their knowledge was as philosophically significant as the knowledge of scholars. Fi makes the moral case personal before it makes it general.

Nothing in Diderot's biography demanded tertiary Te more urgently than the Encyclopédie. The project required coordinating over 150 contributors —scientists, philosophers, craftsmen, physicians, economists—across more than twenty years: negotiating with publishers, managing censors, replacing collaborators who dropped out (d'Alembert resigned the co-editorship in 1758), and continuing to produce his own enormous volume of entries while holding the enterprise together.

What saved the project was Diderot's willingness to make unsentimental decisions. When the publisher Le Breton secretly censored passages from the final volumes after Diderot had already corrected the proofs, Diderot's response was one of the most anguished passages he ever wrote. But he did not collapse; he completed the project. Tertiary Te operates in service of Ne and Fi: it gets the work done. His years writing the Salons for Grimm's newsletter—on demand, on schedule—showed the same pattern: Te in service of someone else's structure, which suited Diderot well.

Diderot left Langres for Paris in 1728 and never returned to live there. Yet Langres never left him. His father, the cutler Didier Diderot, appears throughout his correspondence as a figure of moral seriousness—a craftsman whose practical expertise represented a value the salons could not match. The Encyclopédie's famous plates depicting artisan tools and trades were partly a tribute to that paternal world. Inferior Si works this way: anchoring the dominant intuitive in memory and origin, surfacing as a pull toward what was there before the ideas began.

His Catholic upbringing was a similar case. Diderot broke with the Church early, becoming a materialist who denied the immortality of the soul. But the moral seriousness of his Jesuit education never left; it migrated from theological to humanist grounds. You can take the man out of the Church, but you cannot always take the Church's moral architecture out of the man.

His trip to St. Petersburg in 1773–74 to visit Catherine II showed inferior Si under stress. The journey east at sixty was physically and emotionally exhausting; his daily conversations with Catherine were exhilarating, but the court environment unsettled him. He returned to Paris tired, ill, and grateful to be home in a way that surprised him—the discovery that the particular place and the particular people mattered in ways the grand project had too easily elided.

Why ENFP Over ENTP

The comparison with Voltaire sharpens this. Voltaire managed his celebrity with strategic intelligence; Diderot was repeatedly surprised when his candor got him into trouble. Voltaire knew when to retreat; Diderot kept arguing because he could not separate the intellectual case from the moral one. The ENTP knows when to disengage. The ENFP's Fi makes disengagement feel like betrayal—and the Encyclopédie exists because Diderot never quite disengaged.