The Functional-Delegability Frontier: Rethinking the Industrial Revolution as a Long-Run Historical Process

The Industrial Revolution is commonly periodized through mechanization, steam, electricity, mass production, computing, digital networks, and artificial intelligence. This article proposes an alternative variable of historical observation: the functional-delegability frontier, defined as the historically demonstrated set of functions technically executable by technical systems under identifiable operating conditions. A function is specified independently of its mechanism as F = (I, O, C): admissible inputs, required output, and operating conditions. Analysis distinguishes extensive and intensive expansion, functional flexibility, recursive expansion, and recursive depth. A comparison of employment-based, energy-based, and techno-economic interpretations clarifies their different criteria of historical change. Applications to machine tools, automatic programming, circuit simulation, and code generation identify what the evidence supports and what would require reclassification. The cases document cross-sectoral reuse of production capabilities and the participation of computing in developing subsequent technical systems; they support, without conclusively establishing, the hypothesis of one still-unfolding Industrial Revolution. This interpretation concerns functional reallocation and cumulative dependence across technological discontinuities, not the absence of internal phases. Contemporary evidence is separated from prospective claims, and environmental constraints are treated as conditions of sustainable implementation rather than proof of technical impossibility. The framework identifies technical possibility, not adoption, profitability, labor displacement, or economic destiny.