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Re: Quick cladistics question



Dinogeorge@aol.com wrote:

<snip>

> Cladists are presently trying to move definitions of taxonomic groups away
> from characters ("character-based" definitions) and toward definitions based
> on relationship ("node-based" and "stem-based" definitions). Key characters
> may change with the acquisition of new information and the discovery of new
> fossils, whereas relationships are more stable against such discoveries. 

I don't know very much about cladistics, but based on what I do know the
above seems to be an inherently contradictory position.  OK, you define
clades based on relationships.  How do you define relationships?  How
else can you define relationships except by physical characteristics?   

Further, why would you _want_ a system that is "more stable against new
discoveries?"  Shouldn't the classifications reflect all available
data?  

-- JSW