We are clear that economic thinking needs to step across borders and deal with “externalities”.  This means awareness of the realities of social and historical lives. How to get there? It takes economists who think out of th narrow silo of formalist economics. But we are in fair agreement that the teaching of economics creates,  with a kind of imprinting, students who can think in formal terms but lack the skills for producing effective narratives. So, provocative proposal. Make an undergraduate degree in one of 

History
Anthropology
political science
Archeology
Psychology
Sociology
Literature
Art
Design

a prerequisite for entering phd programs in economics. The cross fertilization will happen rapidly when minds are not colonized by formal economics alone. Economics requires a kind of maturity about society and the fragility of social systems. This proposal for an undergraduate degree first  will lead to an economics filled with more mature students.