Brian: my professor, Marc Tool, used to thunder against all "isms" and if you sat in the front of the class--as I did--he put the fear of god into you. I still hesitate before adding an ism to Institutional.
However as Paul Davidson always says, categorization is essential to building an understanding. As a kid you learn animal, vegetable, mineral and it helps to make sense of the world. You go on to species and learn about cats, dogs, and gold fish. There's a lot of variability across individuals, but more similarities within groups. They mostly mate with their own kind--but a few of the more adventurous try cross-species dallying.
Ditto with schools of thought (at the extreme, isms). Individuals might protest mightily about pigeon-holing and that of course is unfair, but to build understanding the categorization is essential. And cross-species fertilization almost never works.
When I finally went on to grad school, a few months into the program, one of my fellow students told me that I was the only one (of 24 entering first years) who had an ideology. He had never heard of a school of thought. He had thought economics is just economics.
Or, more precisely, economics is just math. Like many of those other students, he struggled trying to make sense of what the heck economics actually is, other than special purpose sets of math equations with no apparent links among them. He and many others did rather poorly that first year; I found grad school to be very easy because I knew which ideology the neoclassical bastards were trying to feed us. I knew it at least as well as they did--probably better. Neoclassicals are by far the most likely to protest that they are not neoclassical.
I've always taken John Harvey's approach to teaching. Schools of thought is the first lecture in any and every class I teach. I cannot imagine making any sense of economics without that.
I am working on revisions to my Contending Perspectives in Econ book and one chapter that I originally intended to write was on ecological economics or econ of sustainability. The existing chapters cover Neoclassicism, Marxism, Austrianism, Post Keynesianism, Institutionalism, New Institutionalism, and Feminism.
Do you consider ecological econ/sustainability a school of thought , per se along the lines of those others or is it a topic area?
Similarly, I have a colleague who uses my book and she's very keen that I add a Public Choice chapter. Same question: school of thought or subject area?
Incidentally, she is an Austrian and yet there is no one in the department whose overall philosophy regarding pedagogy and curriculum matches mine more completely. She's a wonderful person. Who would have thought?!