The Lyapunov horizon.
War and thinking on an uncertain future.
One of the concepts that I’ve found useful in thinking through events is borrowed from the mathematics of systems: a system’s Lyapunov time is essentially the horizon at which it becomes unpredictable. There is real computational work undergirding it, and it is applied to empirically observable systems, for example the state of the solar system (a Lyapunov time of about fifty million years) or a cubic centimeter of an element at triple point (a Lyapunov time shorter than quadrillionths of a second). You cannot compute Lyapunov times for human events — not yet — but the idea of a forecasted horizon at which predictability fails is exceptionally useful in assessing them. (Culturally alert readers will immediately recall Asimov’s classic Foundation series as positing the effective erasure of Lyapunov horizons, although the real-world concept is never named.) Mathematicians and celestial-mechanics experts will therefore forgive me for appropriating, and no doubt simplifying, the term: there is a real sense in which a variety of societal and policy matters may be assessed according to their Lyapunov time.
The desirable endstate is typically a Lyapunov horizon as far out as possible. Social Security is a great example of a governance and policy structure tied tightly to a Lyapunov time, in its case easily defined as the moment the money runs out. Most policies aren’t so clear cut in this sense. The administrative-state project of the past century is probably at its Lyapunov horizon now, but we cannot know except in retrospect. Perceptiveness — and advantage — in governance and society depends in large part upon what German combat theorists used to call fingerspitzengefühl, the “fingertip feeling,” an intuitive sense of when a system has run its course and brought its Lyapunov horizon so close as to be indistinguishable from the now. In this light, you can think of various disruptive activities — terrorism, for example, or some forms of populism — as deliberate attempts to drag the Lyapunov horizon as near as possible.
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