Does up need a down, hot a cold, to have useful meaning?

Do extreme opposites of position serve a useful or net-plus function?

A good commenter discussion happening at Chad Orzel's ScienceBlog, Uncertain Principles: The Cost of Not Framing.

The thing begins with whether Dawkins and PZ meyers and other science advocates hurt their cause and appeal by snorting at the faithful so, umm, zealously? Orzel sez yeas, others chime in.