The least obvious part of a system, its function or purpose, is often the most crucial determinant of the system's behavior. - Donella Meadows

When there are long delays in feedback loops, some sort of foresight is essential.

Don't be stopped by the "if you can't define it and measure it, I don't have to pay attention to it" ploy. No one can [precisely] define or measure justice, democracy, security, freedom, truth, or love. No one can [precisely] define or measure any value. But if no one speaks up for them, if systems aren't designed to produce them, if we don't speak about them and point toward their presence or absence, they will cease to exist.

Models can easily become so complex that they are impenetrable, unexaminable, and virtually unalterable.