Some argued that naturalists looking for a system of classification should try to take into account as many characteristics of a species as possible. That would ensure that their classification system was truly natural. Others argued that we do not find systems in nature but construct them in our minds. Therefore naturalists should invent artificial systems based on a few convenient traits of their own choosing, such as the shape of a plant’s reproductive organs.

"The fundamental elements of any classification are its theoretical commitments, basic units and the criteria for ordering these basic units into a classification. Two fundamentally different sorts of classification are those that reflect structural organization and those that are systematically related to historical development.
    In biological classification, evolution supplies the theoretical orientation. The goal is to make the basic units of classification (taxonomic species) identical to the basic units of biological evolution (evolutionary species). The principle of order is supplied by phylogeny. Species splitting successively through time produce a phylogenetic tree. The primary goal of taxonomy since Darwin has been to reflect these successive splittings in a hierarchical classification made up of species, genera, families, and so on.
    The major point of contention in taxonomy is epistemological. A recurrent complaint against classifications that attempt to reflect phylogeny is that phylogeny cannot be ‘known’ with certainty sufficient to warrant using it as the object of classification. Instead, small but persistent groups of taxonomists have insisted that classifications be more ‘operational’. Instead of attempting to reflect something as difficult to infer as phylogeny, advocates of this position contend that systematics should stick more closely to observational reality." (Hull, 1998).

How do we recognize that, for example, something we see is a duck, a goose, or a swan? Of course we learn so by somebody telling us. The species have been defined before we learn them. The specific attributes, we use to identify them, may, however, vary from person to person (cf., Andersen, Barker & Chen, 1996). The identification is related to our schemata, which again are depending on "paradigms".

How does this relate to the following quote?

"Scientific classification and logical division has worked fairly well in the classification of natural kinds, such as Linnaeus' classification of living things. The reason is that the characteristics chosen, such as the shape of a fruit, are easy to perceive and describe. Furthermore, all biologists and botanists would agree on the interpretation of the characteristics (Lakoff, 1987). Such taxonomies do not intend to analyse the meaning of the terms, but are merely classifications of kinds of things. The chosen characteristics by which the genus is divided into genera are properties of the things classified and the characteristics are subject to inspection. However, the users of such taxonomies know that the use of the classification requires some sort of interpretation. That is why a zoologist would not dispute a statement like 'this cat has three legs,' since he knows that there can be handicapped cats. He would still classify cats as four legged mammals and he would still say that the property of being four-legged belongs to cats, but he would not say that cats are four-legged necessarily or analytically (Eco, 1984). In other words, nothing specific is said about individual cats in such a classification." (Mai, 2004).

"It is my contention that scientific classification of natural objects, and the bibliographic classification of the content of a  document, are distinct for two main reasons. The first has to do with when and how the items are classified, and the second has to do with the nature of the classified items." (Mai, 2004).

Well, I believe that Mai is wrong in this statement. Considering what  Andersen, Barker & Chen (1996) and Ereshefsky (2000) write. To us, it seems so natural to classify those species, but just to say exactly what individuals make up a species is problematic. There are different theories in biology of what species are, there are different "species concepts". Some methods used for classifying animals would actually count three legs in an individual. So, whether or not to disregard such a property by the individual animal requires a theory on how to identify whether an individual belong to a species or not. In biological taxonomy we have, according to Ereshefsky (2000, p. 7) "no fewer than four general schools of taxonomy: evolutionary taxonomy, pheneticism, process cladism, and pattern cladism". Each of those schools have their own view on how to get from the characteristics of an individual organism to a species, and also the meaning of the term species varies between schools of taxonomy.

• Cladistics is a method of rigorous analysis, using "shared derived properties". (Wikipedia, 2006a).

• Evolutionary taxonomy or evolutionary systematics seeks to classify organisms using a combination of phylogenetic relationship and overall similarity (Wikipedia, 2006b).

• Phenetics is a classification based on the statistical similarities between organisms. All characters are given an equal weight and by measuring large number of characters, it was hoped that a stable classification based on overall similarities between organisms would be reached.

"Pheneticists, for example, argue that biological theory has been wrong in the past, so to protect taxonomy from such errors no theoretical assumptions should be used in constructing classifications (Colless 1967, cf. van Fraassen 1980). This empiricist ambition, however, cannot be achieved (Ereshefsky 2001, 186). Each organism has an exceedingly large number of traits – too many to record for a classification. Pheneticists must choose which traits to use in constructing classifications. This demands a theory about which traits are more important than others in constructing classifications. So much for theory neutrality. Some theory or set of beliefs is required for constructing classification, even when positing an initial morphocluster." (Ereshefsky &  Matthen, 2005).

"Many biologists believe that species are groups of organisms that can successfully interbreed and produce fertile offspring. Being a group of organisms with those properties defines membership in the species category."  "The idea that species are groups of organisms that successfully interbreed and produce fertile offspring is just one of many prominent definition of the species category. (Biologists often refer to such definitions as "species concepts"). Another definition asserts that a species is a group of organisms bound by their unique phylogeny, and still another defines a species as a group of organisms that share a unique ecological niche. " (Ereshefsky, 2000, p. 4; see also Ereshefsky, 2002).

So, it seems there are different paradigms within biological taxonomy which are related to different basic epistemologies.

Literature:

Andersen, H., Barker, P. & Chen, X. (1996). Kuhn’s Mature Philosophy of Science and Cognitive Psychology, Philosophical Psychology, 9, 347-363.
 

Anonymous [2003]. Classification, taxonomy and phylogeny of animals. Available:
http://web.archive.org/web/20030706235226/http://www.squ.edu.om/agr/OnlineCourses/Biol2020/Taxonomy/Taxonomy.html

Ashburner, M. et al. (2000). (Gene Ontology Consortium). Gene Ontology: tool for the unification of biology. Nature genetics, 25, 25-29. Available at: http://www.geneontology.org/GO_nature_genetics_2000.pdf

Caldwell, R. et al. (2006). Biological species concept. University of California Museum of Paleontology & the National Center for Science Education.  http://evolution.berkeley.edu/evosite/evo101/VA1BioSpeciesConcept.shtml

Dullemeijer, P. (1980). Dividing biology into disciplines: Chaos or multiformity? Journal Acta Biotheoretica, 29(2), 87-93.

Ereshefsky, M. (2000). The Poverty of the Linnaean Hierarchy: A Philosophical Study of Biological Taxonomy. Cambridge: Cambridge University Press.

Ereshefsky, M. (2002). Species. Stanford Encyclopedia of Philosophy. http://mugwump.pitzer.edu/~bkeeley/SEPspecies06.html

Ereshefsky, M. &  Matthen, M. (2005). Taxonomy, Polymorphism and History: An Introduction to Population Structure Theory. Philosophy of Science, 72, 1-21. http://www.philosophy.ubc.ca/faculty/matthen/Polymorphism%20and%20Taxonomy%20after%20referee.htm

Hull, D. L. (1998). Taxonomy. IN: Routledge Encyclopedia of Philosophy, Version 1.0, London: Routledge.

Karpatschof, B. (2000). Human activity. Contributions to the Anthropological Sciences from a Perspective of Activity Theory. Copenhagen: Dansk Psykologisk Forlag. Available at: Karpatschof_2000

Kellogg, E. A. (1998). Who’s related to whom? Recent results from molecular systematic studies. Current Opinion in Plant Biology, 1, 149–158. http://www.ira.cinvestav.mx:8080/papers/COPB1_149.pdf

Mai, J.-E. (2004). Classification in Context: Relativity, Reality, and Representation. Knowledge Organization, 31(1), 39-48. http://www.ischool.washington.edu/mai/Papers/2004_ClassificationInContext.pdf

Mayr, Ernst (1997). This is biology: The science of the living world. Cambridge, Massachusetts: The Belknap Press.

Mishler, B. D. (2000). Deep Phylogenetic Relationships among "Plants" and Their Implications for Classification. Taxon, 49(4),  661-683. (There has been tremendous recent progress in understanding the relationships of plants, due to two different advances, whose cumulative impact has been great. One advance is theoretical and methodological--a revolution in how any sort of data can be used to reconstruct phylogenies. The other is empirical--the sudden availability of copious new data from the DNA level. This review briefly sets these advances in their historical context, then covers both as to their promise and problems. An important distinction between "shallow" and "deep" phylogenetic studies is developed, and morphological and molecular data are compared as potential phylogenetic markers in that context. Recent results on relationships of plants in general and green plants in particular are then considered. Future directions for classification, particularly the need for rank-free taxonomy, are also discussed in light of the rapidly improving resolution of plant relationships).

Neumann, E. K.; Miller, E. & Wilbanks, J. (2004). What the semantic web could do for the life sciences. DDT: BIOSILICO, 2( 6), 228-236. http://lambda.csail.mit.edu/~chet/papers/others/n/neumann/neumann04biosilico.pdf

Nickrent, D. L. (1999). Plant Biology 304. A Historical Look at Plant Classification. http://www.science.siu.edu/plant-biology/PLB304/Hist.Tax.html

Overmier, Judith A. 1989. The History of Biology: A Selected, Annotated Bibliography. New York; London: Garland.

Stevens, P. F. (1994). The Development of Biological Systematics: Antoine-Laurent de Jussieu, Nature, and the Natural System. New York: Columbia University Press. (A reevaluation of the history of biological systematics that discusses the formative years of the so-called natural system of classification in the eighteenth and nineteenth centuries. Shows how classifications came to be treated as conventions; systematic practice was not linked to clearly articulated theory; there was general confusion over the "shape" of nature; botany, elements of natural history, and systematics were conflated; and systematics took a position near the bottom of the hierarchy of sciences).

Wikipedia, the free encyclopedia. (2006a). Cladistics. http://en.wikipedia.org/wiki/Cladistics

Wikipedia, the free encyclopedia. (2006b). Evolutionary taxonomy.  http://en.wikipedia.org/wiki/Evolutionary_taxonomy

Wikipedia. The free encyclopedia. (2006). Scientific classification. http://en.wikipedia.org/wiki/Scientific_classification

http://www.life.umd.edu/emeritus/Reveal/pbio/nomcl/nicol.html

An Introduction to the Gene Ontology. http://www.geneontology.org/GO.doc.shtml

See also: Biology (Epistemological lifeboat); Cluster, clustering & cluster analysis (Core Concepts in LIS). Linnaean Hierarchy ; Systematics

Birger Hjørland

Last edited: 04-03-2008

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