[Tcs-lc] concepts of Higher taxa

[Martin Pullan]

With regard to Stan's comments regarding defining taxa throgh content I think that it is important to make some very clear distinctions regarding the nature of activities that take place during taxonomic reasearch when modelling concepts.
 
1) A clear distinction must be made between the process of "determination"/identification as opposed to the process of building a classification. New determinations do not add to any existing classifications. Classifications, once published are immutable. If one adheres to this point then the problem of  "cascading taxa " as described by Stan goes away. The TCS should incorparte within it the abilitity to distinguish between determination and classification. 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.
 
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. 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. Again avoiding the problem of "cascading taxa".
 
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. 
 
I do, however, agree with Stan's assertion that a classification is a set of rules for determining membership of a group. The representation  of a group by its members does not break this concept 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". 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. The nested approach will still be agnostic about representing taxa as long as it is not a requirement that all representations extend down to the specimen level.
 
Martin
 
 
 
 
 
 
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