Gerry Sussman gave an interesting keynote talk at AOSD 2007.
What caught my attention was his interest to write
flexible programs that have wiggle room. He is not interested
in writing programs that do one thing. Instead he likes to write generic programs
that do many things. The generic programs are not precisely specified 
and proven correct.

A programmer who uses AP (Adaptive Programming) has similar desires. The functionality that
comes from the adaptive methods can work in infinitely many different class graphs.
We don't want to constrain the methods too much; we prefer to keep them generic.

Demeter Interfaces (ECOOP 2006] give the programmer control to limit the methods
if they would fail for sure.