Quoting "E. Roy Weintraub" <[log in to unmask]>:

> The larger question of course is that of the nature and life of 
> intellectual communities and the border crossings that occur among 
> them.

Good larger question, but some ancillary observations:

1) It is possible -- and indeed not that uncommon -- for someone to be 
a member
of more than one community (think Herbert Simon or, as Anthony Waterman points
out, Keynes).

2) Whether someone is an expert in a community (or taken as making a serious
contribution) depends in part on what uses members of that community put their
contributions to -- sometimes much later.  For example, the work of Haavelmo
and the Cowles Commission on econometrics was seen for most of the last 60
years as inside economics.  But with Nancy Cartwright's Nature's 
Capacities and
Their Measurement (1989), they were taken up by a philosopher of physics as
effectively important contributions to her field, which may (if philosophy has
any import for physics -- as many physicists themselves have believed) give
lessons to physicists on how to handle probability.

Kevin Hoover