complexity measures

[David Lightfoot]

----------------------------Original message----------------------------
   Recent postings suggest that some people believe that languages are all
equally complex (although this is not entailed by Larry Trask's original
question, giving rise to this discussion).
   One possibility is that this belief is an empirical finding.  In which
case, there must be a way of measuring the overall complexity of a language and
somebody has found that languages all emerge with the same index.
Alternatively, it might follow from some basic principles or some
theory that languages must be equally complex. I know of no such
empirical support nor of any theoretical underpinning for such an idea.
What am I missing?
   I should have thought that if there is a simplification in some part
of a system, there doesn't necessarily have to be compensating
complexification elsewhere.