[ue_]

But why? Doesn't that shut out a range of economic theories from the discussion? Classic political economy and its critiques (Marx et al.) I feel are still relevant and useful. If they are not to be studied in economics, then where?

[AndrewKemendo]

Yes in fact it does. Those are all considered "heterodox" economics and are basically ignored.

They are moreso discussed in sociology and philosophy and to a limited extent graduate courses in economics.

[wjnc]

Sociology tends to have more differentiation in what sources are taken as 'canon'. You can probably still find Marxist sociologists, although the field has somewhat collapsed since the 80's.