The psychometric concept of "general intelligence" (Spearman's g) proposes that a minimal set of shared cognitive facilities underlies performance across all domains. This paper distinguishes two fundamentally different conceptions of general intelligence — the minimal-substrate model (Conception 1: a small common denominator of processing capacity) and the maximal-integration model (Conception 2: an exquisite array of diverse, cultivated faculties producing genuine cross-domain competence) — and argues that they are not merely different but that Conception 2 is the more practically powerful and that only one discipline guarantees its development: philosophy. The argument proceeds in three stages. First, we demonstrate that every field of expertise except philosophy has what we term a "domain horizon" — a structural boundary on the kinds of problems the discipline can even formulate, independent of practitioner skill. Second, we argue that genuine philosophical breakthrough — the production of novelty that no previous thinker has achieved — necessarily requires the cultivation of seven specific faculties that together constitute Conception 2 general intelligence. Third, we demonstrate that no other field, by the nature of its subject matter, makes this development structurally necessary rather than merely accidental. The competent breakthrough philosopher is not generally intelligent in the minimal-substrate sense. They are generally intelligent in the only sense that matters practically: they can bring genuine analytical and creative competence to any rigorous problem, in any domain, because philosophy is the only discipline whose subject matter is the foundation of every other discipline.
Brandon Charles Emerick (Tue,) studied this question.