Economics can be a science, social science, a system of principles describing how human actually behaves in society level. It will be a great help when we needs to apply these well-tested principles to (perceived to be) problem.

But it is wrong to equal what we want as science. Optimization is not science, it is the way we do to achieve desired outcome, it is engineering. As in applied domain, optimization goal has to be defined. In nonlinear case, absolute optimum will never be known, only local optima can be reached.

Of course there is relationship between science and application, but the explanation focus is the symbol of science, problem focus is the symbol of application. To solve a problem we cannot constrain ourselves to particular domain (e.g. economics only, or psychology only), we needs to focus on the essence of the problem and use whatever knowledge we have to tackle the problem. This is the fundamental principle of engineering.

By the way, System Dynamics can be think as applied dynamics, a useful tool to apply science of dynamics in many problems, especially when transdisciplinary knowledge is necessary.