Economics since the mid 1900s hasn't been solely focused on mercantilism, but rather has had a significant focus on choice under various conditions, assumptions, and constraints. Game theory, mechanism design, contract and auction deisgn, and focus on individual versus collective behavior (e.g Arrow's Impossibility Theorem) have strong overlap with psychology.
Though there is certainly daylight: my subfields of Industrial Organization and Computational eocnomics are way more related to quantitative finance, ML, and similar than voting behavior.
The thrust of my pithy question was whether or not the principle subjects of economics --- of human production, consumption, and exchange --- where the sum total of all psychological inquiry.
As the parent post tried to substantiate, for current economics the principle subjects really are not limited to human production, consumption and exchange, but also include subfields that focus on all choices that humans make - things like revealed preferences vs expressed preferences or risk aversion are a focus of economics, but they apply to consumption just as well as for other choices people make about e.g. intimate relations or choice of hobbies or music.
Yes, and I'd still argue that psychology's span of breadth is more encompassing. Note that I both studied economics at uni, and have spent considerable time since exploring both the history and current branches of the field. I'm rather familiar with it and my criticisms are rather based on that familiarity.
The relevant questions are:
1. Which field of study encompasses more elements, economics or psychology?
2. Are these fields intersecting, and if so, is one a proper subset of the other or not?
In a Venn diagram sense, how do the sets relate?
Psychology includes numerous branches, fields, divisions, and foci, of which choice determination is only a very small element. See for example:
Note that psychology, economics, sociology, political science, and anthropology all emerged out of what had previously been moral philsophy largely during the 19th century. Divisions and focus are somewhat arbitrary and strongly influenced by institutions and other pressures --- in the case of economics, political policy influences are notoriously strong, though other disciplines aren't immune from same. But if I had to matryoshka the two, I'd nest econ within psych.
Though there is certainly daylight: my subfields of Industrial Organization and Computational eocnomics are way more related to quantitative finance, ML, and similar than voting behavior.