Quotes from Complexity and the Economy

By Brian Arthur (2015)

Agents generally do not optimize in the standard sense, not because they are constrained by finite memory or processing capability, but because the very concept of an optimal course of action often cannot be defined.#
Methodology Epistemology
As humans we are only moderately good at deductive logic, and we make only moderate use of it. But we are superb at seeing or recognizing or matching patterns—behaviors#
Psychology
Equations do well with changes in number or quantities within given categories, but poorly with the appearance of new categories themselves.#
Methodology
If a system contains only negative feedbacks (in economics, diminishing returns) it quickly converges to equilibrium and shows “dead” behavior. If it contains only positive feedbacks, it runs away and shows explosive behavior. With a mixture of both it shows “interesting” or “complex” behavior.#
Methodology
To the degree that outcomes are unknowable, the decision problems they pose are not well-defined. It follows that rationality—pure deductive rationality—is not well-defined either, for the simple reason that there cannot be a logical solution to a problem that is not logically defined. It follows that in such situations deductive rationality is not just a bad assumption; it cannot exist. There might be intelligent behavior, there might be sensible behavior, there might be farsighted behavior, but rigorously speaking there cannot be deductively rational behavior. Therefore we cannot assume it.#
Epistemology Methodology
Complexity is not a theory but a movement in the sciences that studies how the interacting elements in a system create overall patterns, and how these overall patterns in turn cause the interacting elements to change or adapt… Complexity, in other words, asks how individual behaviors might react to the pattern they together create, and how that pattern would alter itself as a result. This#
Methodology Science