A [[qualitative system dynamics model]] focuses on the structure of a system and the qualitative relation between system components.
[[Gordon Brander]] quotes [[Donella Meadows]] from [[Thinking in Systems]] a lot in his latest newsletter. ([[Fragments: vertebrate technology]] - on components, modularity, and [[hierarchy]]).
Undoubtedly a major figure in systems thinking, but [[Robert Biel]] relates that Meadows had somewhat dubious / liberal-minded political views on some things, to which she applied systems thinking.