Why learn outside your field?

My friend is teaching to his Economics Ph.D. students and explaining why they should be interested in topics that are not in their subfield.

The friend asked for statements about why learning from other fields is good. Here was my answer:

Five things:

1. Being a good colleague involves being able to engage thoughtfully with their work. A basic ignorance in most other fields will make that harder and reduce your value as a colleague.
2. The walls between fields are often much thinner than we expect. In its more obvious forms, macro originaly pioneered the use of Bellman equations in growth and consumption/savings, but IO used these methods quite successfully when considering dynamic problems, as did environmental Econ with resource extraction.
3. Paul Krugman’s number one rule in his famous “How I work” essay was “Listen to the Gentiles … Pay attention to what intelligent people are saying, even if they do not have your customs or speak your analytical language.” You may think your field is the best field. That’s fine – you probably like it the most by revealed preference. You would likely be best served as viewing other fields as inspiration for your own field, rather than as gnats to be ignored. Your colleagues in other fields are smart — listen to what they have to say! (If you think you’re the only smart person in your group / department, you’re probably wrong and you’re probably an asshole).
4. You have a long career ahead of you. You might want to work on new topics someday. It’s worth keeping up with the rest of the field!
5. If you’re really lucky, you might someday be an editor at a journal where opinions and thoughts on a wide range of topics is a requirement. You should start now!