[Taxacom] Clade age

Kenneth Kinman kennethkinman at webtv.net
Thu Nov 17 20:17:31 CST 2011

Hi Don,   
       Agreed.  And the worst case in biology of definitions run amuck
is the PhyloCode.  The irony is that continued disagreement among
PhyloCodists over differing definitions has actually impeded the
implementation of PhyloCode (last I saw, I think it was version 4b).  I
guess we can always hope that the infighting continues and that the
delay in implementation might continue indefinitely.        

Don.Colless wrote:             
       I hate to have to agree with John, but happily I can join him in
agreeing (basically) with Curtis. The logical notion of a definition
requires a set of invariant, necessary, and sufficient conditions -
which just doesn't apply in matters empirical. We use (as Curtis
stresses) DIAGNOSES: sets of conditions of which none may be necessary
but a "substantial" number will usually be sufficient. We simply have to
agree, as we usually do, on how many is substantial.

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