Here is another new essay of mine, called The Simplicity Assumption.
The opposite of the Simplicity Assumption would be a complexity diagram. Imagine a diagram with a social problem, such as the obesity epidemic or the financial crisis of 2008, at the center. Then list all of the plausible factors that could have contributed to this problem, and put those on the diagram, with arrows pointing to the central problem. Next, draw arrows that reflect likely feedback loops among these various causal factors. Finally, draw arrows that reflect likely feedback loops from the central problem to some of these causal factors. For a complex problem, this diagram will look rather messy, like a badly tangled ball of kite string; you cannot be sure that tugging on one part of the knotted mess will make things better or worse.
Economists do not work with complexity diagrams. Such diagrams are not conducive to creating tractable models. Not having a tractable model is not conducive to publishing a paper. Not publishing papers is not conducive to having a successful career.
Read the whole thing.