<< I agree that stabilizing selection is a form of selection, and probably the
most common form of selection at this point in time.  [I suspect that
directional selection was more prominent in the earliest stages of life on
earth, and perhaps following mass extinctions.]  However, even stabilizing
selection does not manifest when there is no heritable variation for
fitness.  The most compelling argument I know of supporting your claim that
selection doesn't stop is the general form of the Hamilton/Zuk model of
host/parasite coevolution, which they constructed to underpin the Good Genes
process of epigamic trait evolution. 

Th
But it does slow down - and that may be very important




 The basic point is also effectively
captured by the Red Queen hypothesis.  In a coevolutionary context, the
biotic environment continuously and rapidly changes in response to evolution
of the focal species, which would tend to maintain at least some heritable
variation for fitness.  This argument convinces me to concede that selection
may not stop in regard to traits involved in social or interspecific
interactions when interacting partners are entrained in a coevolutionary
network.  Outside of this context, I remain skeptical.
 >>

If you accept that slection won't stop but might slow down then - doesn't my
model follow:

As adaptation fitness increases,
stabilizing selection increases
and directional and diversifying selection decreases

and vice versa
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