[Taxacom] FW: Reproducibility of descriptive data
s.thorpe at auckland.ac.nz
Fri Sep 11 01:25:43 CDT 2009
[I said] To my mind, it seems to collapse to the absurdity of claiming that an identification/name instance has no meaning unless you can verify that it isn't a misidentification!
This may be a little confusing. Let me try to be clearer:
For the case of genera, if there are competing concepts, equally correct (i.e., only subjectively different), of genus G, then a simple identification as G without reference to which concept is (fairly) meaningless. The issue of misidentification doesn't arise/is irrelevant. Even if you assume that the identification was done "correctly" (i.e, without blunders or incorrect assumptions), you are still left wondering which concept of G was meant. Just asserting that the specimen belongs to G, without specifying which concept of G, is a (fairly) meaningless claim. In practice, though, there may be an assumed element of "G according to prevailing usage", but that is a whole different can of worms...
For the case of species, i.e., Smith's concept of A includes B, but Jones' does not: I say that an identification of a specimen as A, without reference to a concept (Smith or Jones) does have objective meaning (determined by the identity of the type specimen of A, and the natural boundaries surrounding it). Smith and Jones disagree over where the boundaries actually are, but one of them is right and the other is wrong. If I identify a specimen as A, purely with reference to the type specimen of A, plus my guess that the specimen is close enough to the type to be within the likely reproductive boundaries, then I have made a perfectly meaningful identification, which is either correct or not. I don't have to specify whether or not I would also identify a "typical B" as A, in order for my identification to have any meaning! I can leave that undecided ...
From: Stephen Thorpe
Sent: Friday, 11 September 2009 4:55 p.m.
To: Jim Croft
Cc: Mike Dallwitz; TAXACOM
Subject: RE: [Taxacom] Reproducibility of descriptive data
Just to throw a spanner in the works (!), there is something else that Jim might "really mean" by species concepts. If so, then such concepts are defined by inclusions (of specimens), but not quite in the way that Jim seems to think. Consider this:
taxonomist Smith considers B to be a ("subjective") synonym of A
taxonomist Jones disagrees and considers them to be distinct
identifier Brown identifies some specimens as A
Jim wants to include Brown's identification in his database, but exclaims "by crikey, mate! Did you mean that they are A sensu Smith, or A sensu Jones?" It might not matter if the specimens are "typical A", and so fit both concepts equally well, but what if they are "typical B"???
So, there appears, at least on first glance, to be a notion of species concept defined by inclusion of synonyms (i.e., type specimens). So, now the questions become: (1) is that notion well-defined; and (2) is it important?
I think that, although it is called "subjective synonymy", this is misleading for species. The distinction is really one of what you might call "taxonomic synonymy" vs. "nomenclatural synonymy", not "subjective" vs. "objective"! On my "natural boundary" view of species, Smith is (objectively) either right or wrong, and Jones the opposite.
Note that Brown might have misidentified the specimens altogether, so they may be neither A sensu Smith, nor A sensu Jones! On my view, either A sensu Smith or A sensu Jones is a misidentification anyway, so isn't what we really want to know "is Brown's identification correct?", and not whether it is correct sensu Smith or sensu Jones?
If we don't know which sense of A (Smith or Jones) is the correct one, which is the typical situation, then it seems to make sense to keep track of which sense specimens have been identified. But is this possible in practice? If possible, is it even worthwhile? Remember that Brown could have misidentified the specimens for any number of reasons, not just by choosing to follow Smith over Jones or vice versa. Perhaps, Brown just saw a specimen, identical to his specimens, which had a spurious label on it saying "Holotype of A"! Maybe we could track down that specimen and see if it fits A sensu Smith, or A sensu Jones, or A sensu neither ... Doesn't sound very practical to me! To my mind, it seems to collapse to the absurdity of claiming that an identification/name instance has no meaning unless you can verify that it isn't a misidentification!
I think that whenever we encounter a name instance, we must be aware that it may be a misidentification, but we can't hope to track the reasons why it might be a misidentification (= the basis for the identification), because that basis may be a complex and vague mixture of factors, and not just simply a matter of having followed either Smith or Jones. It also doesn't make much sense to me to give Smith and Jones' concepts any special status compared with the huge number of other POSSIBLE concepts (defined by synonymy) for the same name, that nobody has proposed yet!
These are just my preliminary thoughts on this matter...
From: Jim Croft [jim.croft at gmail.com]
Sent: Friday, 11 September 2009 9:15 a.m.
To: Stephen Thorpe
Cc: Mike Dallwitz; TAXACOM
Subject: Re: [Taxacom] Reproducibility of descriptive data
Descriptions do not 'define' a concept (at any level). They... um...
If you want a definition, you could use the list of those thing you
might include in that concept. Species in genera, specimens in
Having settled on a concept by inclusion, you can then go about
describing it, listing the characters/attributes that, in your mind,
set the boundaries. It is conceivable that a taxonomist could account
for all relevant specimens, species, etc. This is, after all, why we
do revisions. Any character/attribute list is arbitrarily selected
and can never be complete.
Your 'country' analogy is spurious. Like the US, Australia is an
historical federation, defined by inclusion of various bits of land,
including disjunct offshore islands and territories. That the bulk of
Australia happens to coincide with recognizable continent is an
irrelevant artefact. Notions of artificial or real in this context
have no meaning.
On Thu, Sep 10, 2009 at 9:26 AM, Stephen Thorpe<s.thorpe at auckland.ac.nz> wrote:
> Jim, put another way:
> Genera are defined by descriptions (= genus boundary circumscriptions)
> Species are defined by nominating an individual as the type. Species descriptions (=species boundary circumscriptions) do not define the species. They can be incorrect descriptions of the true boundaries (unlike generic descriptions)
> Analogy: Australia can be defined by sticking a flag in the ground and saying "I hereby define Australia to be all the land in all directions from this flag to the sea". So, Australia is like a species (it has natural boundaries). U.S.A. is like a genus (it has artificial boundaries).
> Your "taxon concepts" are a mixture of two very different things: (1) generic descriptions; and (2) species descriptions.
> From: Jim Croft [jim.croft at gmail.com]
> Sent: Thursday, 10 September 2009 9:46 a.m.
> To: Stephen Thorpe
> Cc: Mike Dallwitz; TAXACOM
> Subject: Re: [Taxacom] Reproducibility of descriptive data
> Don't buy this. At all. And I do not think the codes do either. Nor
> many/most taxonomists. The type does not define the species (which
> are in nearly every case variable). It is an exemplar (not always
> 'typical' in the English sense) which anchors the name. The extreme
> example of this are species that have multiple synonymic types. In a
> type-defined species, concepts of lumping and splitting have no
> meaning - yet we all do it.
> Have a chat to Pete deVries. He would argue that a species knows what
> a species is and does not care what we call it or think it is. Humans
> develop a concept of what we think it is, sometimes (maybe even often)
> a reasonably good approximation of what a species knows it is. And we
> give a name to this human concept a name.
> There are three things: a species entity, a species concept and
> species name. The first is defined by biology and evolution, the
> second by humans, and the third is defined by the code and selected by
> The problem we have, and why taxacom exists at all, is someone utters
> the third, a listener assumes the first, without considering the
> second, of which there are often several alternatives.
> On Thu, Sep 10, 2009 at 7:03 AM, Stephen Thorpe<s.thorpe at auckland.ac.nz> wrote:
>> [Mike Dallwitz wrote] _Whatever_ we want to say about a taxon (e.g. what its boundaries, distribution, abundance, or uses are), we need to define the
>> taxon that we want to talk about. And the only way to do that is to describe it in a reproducible way, so that people can identify individuals as belonging or not belonging to the taxon
>> [reply] Species are defined by their name-bearing types (holotypes or lectotypes or neotypes or syntypes). A description of a species is a circumscription of its boundaries, according to the describer. So, we don't describe a taxon in order to define it so that we can then talk about boundaries. Rather, by describing it, we ARE talking about its boundaries, but the species is defined by its type.
>>>describe it in a reproducible way, so that people can identify individuals as belonging or not belonging to the taxon
>> No, describing it in a reproducible way only allows people to identify individuals as being within or else outside the boundaries of the species as circumscribed in the description. These boundaries could be wrong, so the description is certainly not a DEFINITION of the species (definitions are true by definition and cannot be wrong!)
>> What you say applies more to genera and other "subjective" taxa, but not to species, which are objectively defined once a type is designated...
> Jim Croft ~ jim.croft at gmail.com ~ +61-2-62509499 ~
> ... in pursuit of the meaning of leaf ...
> ... 'All is leaf' ('Alles ist Blatt') - Goethe
Jim Croft ~ jim.croft at gmail.com ~ +61-2-62509499 ~
... in pursuit of the meaning of leaf ...
... 'All is leaf' ('Alles ist Blatt') - Goethe
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