The Fallacy of Universal Intelligence
Separating Theoretical Potential from Practical Reality
David Deutsch, influenced by Karl Popper's philosophy, intriguingly suggests that all humans possess equal intelligence, differing only in the knowledge and explanations they've acquired. However appealing, this claim collapses under scrutiny. It commits a fundamental category mistake: conflating universal explanatory capacity with actual cognitive performance.
Deutsch emphasizes a profound human trait: we are "universal explainers," theoretically capable of grasping any computable idea or explanation. This parallels Turing completeness in computers—any Turing-complete system, from a simple calculator to a supercomputer, can theoretically compute the same functions, given unlimited time and resources. Yet, practically speaking, no physical computer ever truly achieves this idealized universality, as real machines have finite memory and speed constraints. Similarly, asserting equal intelligence among all humans because of our theoretical explanatory potential overlooks significant practical realities.
To be clear, Deutsch emphasizes theoretical explanatory universality, not practical cognitive equivalence. This critique specifically addresses the practical implications of this distinction, highlighting why the theoretical idealization doesn't meaningfully reflect real-world cognitive differences.
Deutsch has attempted to defend this claim by suggesting human intelligence could theoretically be augmented with enhanced memory or computational capabilities. However, this approach shifts definitions and engages in speculative hypotheticals, blurring what it means to be "human." Radical cognitive augmentation would fundamentally alter cognitive structures and subjective experience, arguably creating an entirely different kind of intelligence rather than preserving human universality.
Furthermore, just as real computers approach but never fully achieve theoretical universality due to finite resources, human brains face practical cognitive constraints. Our finite memory, limited attention spans, and processing speed inherently restrict our ability to understand certain explanations, especially those potentially accessible to superintelligent AI or alien intelligences possessing fundamentally different cognitive architectures. Such entities could naturally grasp explanations inaccessible to the human mind, simply due to structural and resource-based differences.
Deutsch’s position ultimately fails due to the fundamental confusion between idealized universality and practical cognitive effectiveness. Recognizing that theoretical explanatory universality does not equate to equal practical intelligence allows for clearer, more nuanced thinking. Far from diminishing human dignity or potential, acknowledging genuine cognitive differences provides a realistic appreciation of both the remarkable capacities and inherent limitations of human minds.