I have a couple comments on Mason's post.

First, I think it it Frank, not Charles Ramsey.

Second, here is one case where I think the earlier work has been superseded by new developments. In the 1970s Ramsey's work on taxation  was  extended in the work of Diamond Mirrless. It was one of the contributions Mirrless got the Nobel Prize for. They took into account much more complicated interrelationships than Ramsey had,  and showed when the Ramsey rule applied and when it didn't. As I remember it was all done in excess demand functions so, in their framework, talking about demand also included supply considerations (but not economies of scale issues.  Work was also extended the issues to the income tax, and one of the results I proved back when I was a graduate student was that for efficiency considerations alone, a regressive tax was preferred to a progressive tax. The reason is that a regressive tax on low income individuals works as a lump sum tax on high income individuals.  (That's only for efficiency considerations--not for equity considerations.)

David Colander