Plasticity-Weighted Intelligence: A Multiplicative Model of Knowledge and Curiosity

Traditional intelligence models treat knowledge accumulation and cognitive flexibility as parallel but independent factors (e.g., Cattell's Gc and Gf). This paper proposes a simple reformulation: intelligence as a multiplicative function of accumulated knowledge (K) and plasticity (P), where P acts as a coefficient modulating the expression of K. Under this model, I = K × P, cognitive vitality depends not on K alone but on the preservation of P across the lifespan. The model accounts for several everyday observations that standard additive or IQ-based frameworks leave unexplained: the qualitative difference between high-knowledge individuals with and without sustained curiosity, the cognitive decline associated with reduced plasticity in aging, and the subjective phenomenology of learning (temporal and perceptual richness) reported during states of high P. We position the model relative to existing work on fluid/crystallized intelligence, growth mindset, and neuroplasticity, and discuss implications for education, aging, and self-assessment. The model's primary limitation—the operationalization of P—is addressed as an open question for future empirical work.