"Arcane" / "prevailing usage"

Sat Aug 24 18:09:53 CDT 2002

Christian Thompson wrote in response to Wolfgang Lorenz:

> What is "prevailing usage"?
> This is defined in the glossary as " ... that usage of the name which
> is adopted by at least a concerning with the relevant taxon,
> irrespective of how long ago their work was published."

This wording in the Code falls far short of providing a definition. For
the latter, the critical terms "substantial" and "most recent" would
themselves have to be defined such that a practicing taxonomist
examining any given case would be able to come up with a determination
of "prevailing usage" that is scientifically reproducible, so that not
only a "substantial majority" but all of his peers will have to agree
with it. "Prevailing usage" and all other Code instruments are supposed
to promote the stability of nomenclature. Instead, since the term is
insufficiently defined, we will likely see many cases in which different
authors attempting to evaluate "prevailing usage" will arrive at
different results, with the obvious detrimental effects on stability.

This lack of precision - which is violating an "essential" requirement
for terms according to the Code's own preamble (fourth paragraph) -
makes the installation of "prevailing usage" as a critical element in
many Articles of the Code's fourth edition a very unfortunate
development that seriously endangers stability.

But even if precisely defined, "prevailing usage" would still be a
flawed concept, work against the stability of nomenclature, and burden
the practicing taxonomist with needless work, especially if - as in some
parts of the ICZN Code's fourth edition - it is ranked above original
publications and type specimens. For what proportion of scientific names
are the respective current "prevailing usages" so intuitively and
unanimously recognizable that we need neither recourse to the original
publication and the type material nor a global literature search to
actually document "prevailing usage"? There may be a lot of such cases,
but the transition to ambiguous and then completely open cases is a
gradual one, so how do we decide at what degree of ambiguity to enter
the pain of factually reevaluating the current "prevailing usage"
(assuming that we had a definition for the latter)?
In the recent discussion of the "arcane" thread, some people thought
that looking up the original data on a taxon was too much to ask for.
Obviously, the "prevailing usage" development isn't going to win the
ICZN more followers. In most cases, it will be much easier to find and
interpret the one original publication and the type material than to
honestly tally all subsequent records of the name in question and then
determine who among these later authors had what actual species in his

But even if we give "prevailing usage" still more benefit of the doubt
and assume it was working as apparently intended by the current ICZN:
what will be the effect of its continued application in the future? By
nature of its concept, "prevailing usage" is a kind of sliding scale
("most recent authors"), it does not guarantee that future use of any
name will agree with that of the present or past. Do we not care whether
we are still talking about the same organims the original describers
had, and whether our successors will talk about the same now important
to us?
Moreover, unless amended with a measure of quality control "prevailing
usage" values all individual records equally, regardless of whether they
were made by the original author of a taxon, by a second author
misdetermining that taxon, or by the seventh to twentieth person in line
each repeating an incorrect spelling introduced by the sixth author.
Because subsequent errors cannot be excluded, this practice, instead of
promoting stability, by logical necessity leads to progressive
deterioriation of the information in the system, as always when
'democratic' principles are misapplied to problems whose solution
requires expert knowledge that only few people have.
In any case, under the relativity of "prevailing usage" the stability of
nomenclature cannot possibly be served as well as when the original
publication and the type material are maintained as the one and only
definitive basis for any particular taxon.
Besides, when we set out to follow this exhausting path to its distant
end, we'll have to kiss the original author principle good-bye, for it
will be left behind.
Why keep ascribing authorship to the original author if we don't need to
compare his material, or can even intentionally abandon his perfectly
useful type material in favor of some self-defined "prevailing usage"?
Are we not hoping for more young colleagues to become taxonomists and
help describe the disappearing biota? Well, why I should I go on
describing things if down the road my work doesn't count any more than
that of others who are not required by the Code to compare my type
material but are free to misinterpret and distort what I wrote, without
any restrictions transfer the species to any number of other genera,

Wolfgang Lorenz wrote:

> And I think there's a logic problem with 'prevailing usage', because
> there are actually two different definitions for that important new
> expression,
> despite the clear words on page XIII of the Code: "the meaning of a
> word or expression is to be taken as that given in the Glossary (see
> Article 89)".
> Article 23.9.1. does have its own clear definition different from the
> Glossary definition, ... a bug?

Not at all. Article 23.9.1. defines only for certain cases of homonymy
or synonymy the conditions under which precedence is to be reversed in
favor of "prevailing usage". The glossary 'definition', less precise but
not contradicting, must be taken to apply everywhere else.
According to Lorenz's quote from p. XIII of the Code, it is not
justified to transfer the conditions required within 23.9.1. to
"prevailing usage" applications outside of that Article.

Nevertheless, even the "prevailing usage" coin has its flip side.
Another quote from Chris Thompson:

> A student ... noticed that an obscure spider name, which has only been
> published THREE times, was misspelt in the two subsequent
> publications. Hence, under the new ICZN article 33.3.1., that
> misspelling is now the CORRECT spelling. It does not matter that the
> two subsequent misspellings are ancient, last century, very obscure,
> etc., only that 2 is a substantial majority of 3!

Considering the imprecision of the ICZN Code's definition of "prevailing
usage", I don't think one has to step outside of the Code's rules in
order to "do what is right" in this case. In the absence of a definition
of "substantial majority", who decides whether two to one is enough?
Since the Code's 'definition' of "prevailing usage" does not do so, it
appears to be up to the individual revising author. We cannot accuse the
Code of restricting our taxonomic 'freedom' here. Besides, if only three
people have written about a certain taxon, and all of them about 100
years ago, I seriously doubt that there is any "prevailing" usage in the
first place. Here, the imprecision (or intentional ambiguity?) of the
instrument can be turned into a positive. The Code does not state
anywhere that a name has to have a "prevailing usage" to be valid.
Besides, I see nothing in the Code that would force me to interpret the
overriding Code principle, stability of nomenclature, as stability in
the shortest term. And the Code's "Explanatory note", "Introduction" and
"Preamble" reflect the ICZN's hope to not see authors misuse Articles
for hair-splitting against general principles and reason.
Therefore, "civil disobedience" of the Code does not seem necessary in
the above or similar cases, and I find it - sorry Chris - dangerous to
advocate such behavior. As my above discussion of the "prevailing usage"
concept shows, I am by no means an uncritical fan of the ICZN or the
current Code edition. But as long as there is no other, equally widely
accepted, possibly even better set of guidelines for nomenclature to go
by, it is clearly preferable to work within the Code system, flaws and
all, than to return to a situation like before the first International
Rules, with everybody doing whatever the heck they please.
With the Code, we at least get the opportunity to develop scientific
procedures and to have most taxonomic actions taken and tested by
'objective' criteria. Therefore, the ICZN Code should be improved where
necessary, and if we don't like where the Commission is trying to take
us, well, I suppose its personal composition could be changed.

Bottom line, as in a number of previous postings within these two
Stability of nomenclature - although of course insignificant compared to
the stability of the living world we depend on - is still important and
ought to be protected and promoted by everyone involved with scientific
names of organisms. Just like in the real world where we only have one
system, chances are that in taxonomy too the purpose is best served by
working together to improve the existing system, rather than for
everybody to point fingers at each other or start their own, separate


Martin Spies
Schraemelstr. 151
D-81247 Muenchen

Email: spies at zi.biologie.uni-muenchen.de

Tel. (ZSM) +49 89 8107 153
Fax (ZSM) +49 89 8107 300

More information about the Taxacom mailing list