All good points. In the US today (and this may or may not be an
artifact of our voting system; not going to argue that right now) 90%
or more of the variance between members of congress can be explained
by one axis (going by
http://voteview.com/ and their NOMINATE data),
generally understood as a left/right economic axis, while even in the
recent past, there was much more need for two axes; the economic one,
and one for views on civil rights for African Americans. Now, that's
no longer an issue which cuts across political-economic lines.
--
Dale Sheldon-Hess