[Taxacom] Clade age

Don.Colless at csiro.au Don.Colless at csiro.au
Wed Nov 16 23:04:22 CST 2011

I hate to have to agree with John, but happily I can join him in agreeing (basically) with Curtis. The logical notion of a definition requires a set of invariant, necessary, and sufficient conditions - which just doesn't apply in matters empirical. We use (as Curtis stresses) DIAGNOSES: sets of conditions of which none may be necessary but a "substantial" number will usually be sufficient. We simply have to agree, as we usually do, on how many is substantial.

Donald H. Colless
CSIRO Ecosystem Sciences
GPO Box 1700
Canberra 2601
don.colless at csiro.au
tuz li munz est miens envirun
From: taxacom-bounces at mailman.nhm.ku.edu [taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Curtis Clark [lists at curtisclark.org]
Sent: 15 November 2011 06:21
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Clade age

On 11/14/2011 8:40 AM, Richard Jensen wrote:
> Unfortunately, the one thing you and John agree on is a mistake.
> Definitions do matter.  They are essential for understandable
> communication.  If you are allowed to define "science" by your criteria,
> and I am allowed to define it by a different set of properties, then how
> can we ever communicate effectively?

Science is a human construct, and of course needs to be defined for
effective discourse.

Many of us consider "carbon" to be a natural entity that exists
independent of human perception. We could define it as all atoms with
six protons, and as a "working definition", that's fine, but it's really
a diagnosis, a summarization of a consistent observation.

Many of us consider "species" to be natural groupings of organisms that
exist independent of human perception. It has been a while since
scientists tried to define individual species (Linnaeus was one of the
last famous examples), but people still try to define the "species
concept". It seems to me a diagnosis is again the best approach: what
are the commonalities of the entities we call species? Any single
species "definition" will invariably leave out an entity that some group
of competent biologists calls a species. And by defining "species", we
end up knowing only what we know about it, without an easy route to
learning more.

> John has made this argument before and it appears to be part of the
> problem in communicating with him.  His definitions often are quite
> different from those that many (most!) of us use and that only serves to
> create confusion and a lot of unnecessary exchanges on Taxacom.

John plays fast and loose with definitions of human constructs. I agree
that this impedes communication, and I have called him out on it. But to
me this is quite different from defining or refusing to define observed
entities in nature.

Curtis Clark http://www.csupomona.edu/~jcclark/
Professor, Biological Sciences                   +1 909 979 6371

Curtis Clark                  http://www.csupomona.edu/~jcclark/
Professor, Biological Sciences                   +1 909 979 6371


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