The limits of dynamical systemsWhen reasoning about some aspect of the world with the tools of dynamical systems theory, we associate with each relevant entity a variable that holds the value of a quantifiable property (such as, position, momentum, concentration, wealth, energy). The interactions among entities are viewed as causing the associated quantities to change. These changes are formalized by fixing the functional form of the dependencies (possibly allowing for floating coupling coefficients) among the variables of the dynamical system. Such an abstraction yields a set of coupled differential equations describing the space and time evolution of quantitities related to entities that interact in a predefined and fixed way. The collective phenomena, or units of aggregation, captured by this methodology are self-sustaining patterns of quantitative change. The theory provides a classification of such patterns as attractors in phase space (e.g., fixed points, limit cycles, chaos) and techniques to assess their stability.
The price for this framework is keeping the entities outside of it. As a point in fact,that which changes endogenously are quantities associated with entities, not the entities themselves. The entities that constitute a system cannot change endogenously, for their internal structure is either irrelevant in the formal setup of a dynamical system, or it is disconnected from any action that causes structural change in other entities.