Hi Nico,
This might quickly turn into a test of endurance for allinvolved.
:-)
Disagree,
There's a lot of stuff I wrote that you quoted, and I'm not sure if you diagree with all of it, or just parts of it; but I'll respond to the bits you commented on.
on the following grounds. The basic model of reference in play is (crudely): uses of human language <==> some sort of mapping/reference <==> entities in nature.
I guess I need to understand what you mean by "entities". Is a taxon an entity in nature (existinting independantly of a human's definition of it), in your view? If so, we may be stuck on first principles, at which point the safest thing to do (for all parties involved) is to agree to disagree.
I'm also struggling to understand the scope of "uses of human language". Are we talking just taxon name-labels? Or do you also include the way we refer to diagnostic characters and such?
This model allows for the mapping of language to nature to be spot on or way off, which is critical for proper modeling of taxonomic practice through time. Using precise terminology, a taxonomic concept could never be a clade, that would be nature (on the right side of the equation), but a best a perceived clade, according to a particular perspective.
Hmmmm...I would say that sentiment applies to all notions of "taxon concept", regardless of whether they're framed as a clade or in some other way.
In addition, there can be valid concepts that are not clades (in the Hennigian/phylogenetic sense), and not even intended to be clades, for example in groups with lots of horizontal gene transfer or at and below the species level. In short, concepts are meant to variously refer to clades or other reference-worthy groups in nature, but they are not fruitfully equated with clades themselves.
Fair enough. Keep in mind that I'm not a clade-warrior - I was only using it as a way to illustrate a somewhat less fuzzy/more objective mechanim for defining a meaningful circumscription of organisms. If one defined the taxon concept circumscription as "all individuals containing genetic material inherited from the most recent common ancestor of this specimen and that specimen", you'll at least have the *potential* to come a hell of a lot closer to objectively determining "within" circumscription vs. "outside" circumscription; compared with almost any other mechanism for doing so. Obviously, hybridization, introgression and (I forgot to include this -- thanks for the catch) lateral gene transfer mess this up. But they mess it up a lot less than most other methods for determining inside vs. outside circumscription.
Many historically published published make use of a combination of ostensive components (things being pointed to; type specimens, type species, other members) and intensional components (properties being referenced; diagnostic features, synapomorphies, metabolic functions, etc.). Each component has strengths and weaknesses, but it's hard for me to image that we can do a passable representation job focusing mainly on one and not the other. I'll leave it at that.
No argument here! I'd even take it a step further, in that rarely do we achieve a passable representation even when focusing on *both*. Bottom line: we (as a community) just don't have enough clarity and/or consensus on what a taxon concept should be, and how it should be defined, that we can realistically approach an objective detrmination of whether a particular organisms is within vs. outside a particular taxon concept circumscription.
If I understood the rest of your message correctly, we seem to agree on the part relevant to this list -- that is, how to represent the relationship between an organism (i.e., "Individual") and an implied taxon concept.
Aloha, Rich