[Tcs-lc] concepts of Higher taxa

Richard Pyle deepreef at bishopmuseum.org
Wed Mar 30 22:12:28 PST 2005


Martin wrote:

> The TCS should incorparte within it the abilitity to distinguish 
> between determination and classification. 

I agree -- but I think it already does this.

> Indeed from my somewhat purist standpoint determinations have no 
> place in the TCS but are an example of the application of 
> classifications which will require a separate standard.

Well...aren't SpecimenCircumscription instances ultimately determinations?  If so, then I most definitely think they belong in TCS. >From my purist standpoint, they are the only tangible markers of circumscription boundaries.  Perhaps I misunderstand your point?

> 2) I also believe that it is erroneous to consider that the pubication 
> of new species constitutes an expansion of of the existing concepts of 
> the higher taxon to which they are stated to belong. 

In my view, it may or may not.  Whether or not the publication of a new species within a genus expands the genus concept in which it was placed (relative, e.g., to the concept intended by the original creation of the genus name) depends on subjective judgement. In most cases, I suspect that it does not (should not) alter the genus circumscription.

> This will only occur when a new revision of the higher taxon is undertaken. 
> Up until that point the new species have no official existence within any 
> classification.

I'm not sure I follow.  Are you saying that the description of a new species (by itself), including its placement within a genus, does not represent a form of classification?  I think it does: the new species was classified as belonging to the genus.

> To continue this point without taking a nested approach to defining higher 
> taxa it becomes very hard to discern what is meant by a taxon within 
> the existing incarnation of the TCS. Although it is perhaps a little 
> late in the day to make this suggestion it may perhaps be advantgeous to 
> rethink some of the terminology. What I would like to see is that the 
> TCS is used for the transfer of classifications in which a single TCS 
> entity represents a classification. Embedded within this are the various 
> taxon concepts that constitute the classification being represented. 

Hmmm.  Could this be represented as an external "wrapper" schema, using TCS concept instances as the concept "units", and building a classification around them?  Or would that represent too much overlap with what is already embedded among Relationships and RelatinshipAssertions within the exiting TCS?

> I do, however, agree with Stan's assertion that a classification is a 
> set of rules for determining membership of a group. 

I agree with this point as well.

> The representation of a group by its members does not break this concept 

Ouch...did you mean "Concept", or "concept"... :-)

Seriously, though -- I do agree.

> it is just a question of what is being modelled. Representing ( I think 
> I prefer that term to defining) the group by listing its members is simply 
> representing the results of applying the rules at the time the rules 
> where "written". 

I think that a listing of members contained within a group is indeed a "representation" of the total set of members intended to be included within the group.  However, I think that the group is still *defined* as the total sum of all of its members.  Given that no taxon (with the possible exception of Nessiteras rhombopteryx) has ever had every single one of its members (i.e., individual organisms living, recently dead, and yet to be born) enumerated, I believe you are correct that for practical purposes, we only "represent" concepts by enumerating a subset of their members -- we never actually "define" concepts by enumerating their members.

> At the moment, in the absence of a formal and standard means of 
> representing  the "rules of inclusion"  I think the "representation 
> by membership" approach is the best way forward - at least it is a 
> pragramitc way forward that offers of reasonable chance of performing 
> some comparison of concepts.

I agree, but at the same time, I don't think that "CharacterCircumscription" should be eliminated as a root element of TCS.

Aloha,
Rich




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