Friedman and I have one thing in common, which is a belief in the fundamental importance of the theory of well-founded sets.
We both belief that its signficance is not only in mathematical logic, nor even in mathematics, but also for philosophy and
for many other disciplines.

I don't however see much in common in our conceptions of what the importance of set theory is.

I would describe Harvey's conception as being about what I would call "proof theoretic strength" perhaps better "consistency
strength", but which Harvey might call "interpretive power", and I agree that this is one of the important things which is
supplied uniquely well by set theory.