Hi Mark,
I agree with everything you say (which is why I think that essentially everything related to "taxa" should be represented through Usage Instances). I also agree that taxonomists do not often articulate the scope of their taxon concepts by enumerating the included organisms. However, I would argue that when most (all?) taxonomists conceive of a taxon concept, the "essence" of the concept is the set of organisms implied to be circumscribed by it. Thus, there is an historical disconnect between what a taxonomist means by a taxon concept, and how a taxonomist articulates the scope of that concept. And therein lies what I think is the biggest biodiversity informatics challenge. That is, one of the most fundamental units of biology has a history of being very imprecisely defined by the practitioners who establish those units.
Aloha, Rich
-----Original Message----- From: Mark Wilden [mailto:mark@mwilden.com] Sent: Tuesday, July 06, 2010 5:46 AM To: Richard Pyle Subject: Re: [tdwg-content] Taxon Concept dilemma
On Tue, Jul 6, 2010 at 6:10 AM, Richard Pyle deepreef@bishopmuseum.org wrote:
This is why the only way we're going to be able to establish RelationshipAssertions (sensu TCS) is via third-party
assertions. In
other words, someone is going to have to assert an opinion over whether the implied members of Smith's Aus bus would have
included the
population in Hawaii, and whether the implied set of Jones' Aus cus would have included the population in the Marshall Islands.
I think that a "someone" is always asserting such an opinion
- Smith and Jones included. There is no Platonic ideal of a particular
species. Every single classification is a matter of educated opinion. Smith has one opinion and Jones has another opinion. Brown may step in and decide that Smith's opinion is the correct one - but that's just another opinion. Consumers of the classification choose whose opinions are the most useful.
A taxon is always related to a taxon-assigner. In this sense, "circumscription" is perhaps not the best way to think about it, because very few assigners actually determine taxa by enumerating organisms.
The idea of researchers creating taxa, and third parties adjudicating them to arrive at the "true" classification, is too limited. It's third parties all the way down.
///ark