Names and nomenclature in classification

One of the main focuses in the literature, especially in biology, regarding classification is the problem of nomenclature, of names. Many treat classification as being all about names, an error that is akin to mistaking not the map for the territory, but the names on the map for the territory. Recognizing this, many biologists and philosophers think of classification as just about names, subject to the philosophical problems of names as definite descriptions, with the associated problems of opacity of reference, and so on.* Treating names in classification as merely a matter of semantic convenience has led many to think that classification is not something terribly deep in the natural sciences.

Naming has a conventional element, of course. It does not matter much if we call a species by a Latin name or a German name, so long as the name is unambiguous, and shared by all. The reason why Linnaeus’ scheme was so successful is that he took the confusion of folk names in various languages, and the definite description names in prior work (in which the “name” of a taxon was a description of key characters up to a dozen words long, hardly useful) and replaced them with a simple two-part name, of genus (the wider group) and species (the most restricted group). This convention meant that communication was now simpler, and ambiguities of reference no longer a major problem, although of course that reference was now the focus, both in terms of taxonomic lumping and splitting of names, and in terms of what it was that the names did refer to.

Taxonomists are often very attached to the naming schemes for their domains. There are a number of reasons for this. One, the most obvious and important, is the amount of investment of time and resources that a naming scheme requires. It takes effort to find, describe, and name a taxon, and then for students and other specialists to learn it and the scheme within which it resides. Changes to this are expensive, and so there had better be a good reason to make them. Nevertheless, there is a constant rate of turnover in names and groups in traditional taxonomy. In the Pinnipeds, for example, around 40% of taxa have been renamed, collapsed into synonyms, or split into different groups, at all ranks since Linnaeus first described them. Why does this happen?

A naive empiricist might think that it is driven largely or entirely by new data, better descriptions and specimens, and so forth, but there are many other reasons why a taxonomy might change, and they are often the same reason why a taxonomy might remain unchanged, or be defended:

2. National or ethnic preference and status. Naming rights in the imperial period were a matter of status and political power. People who were trained up in a given system tend to prefer their own scheme over those of competing nations. While Britain adopted the Linnaean system early in the nineteenth century, largely under the influence of James Edward Smith, at first the French rejected it in favor of the “total evidence” approach of Jussieu, and this tension persisted until after the middle of the century. Many German authors rejected both in favor of a largely morphological scheme based on Goethean and Naturphilosophische principles.
3. Disciplinary history. For example, the anatomical nomenclature that developed within medicine for bones and musculature is largely independent of the nomenclature developed for animal anatomy in veterinary science and biology. This makes cross-comparisons rather difficult at times.
4. Politics in science. As naming rights are a measure of standing in some sciences – whoever names the taxon first is going to be cited extensively – attempts to change or defend a taxonomy will depend on whose interest are being advanced. This applies at the individual level, but also at the level of research groups and programs, schools, and of course professional institutions. Competing interests drive much of the debates and conflicts in nomenclature.
5. Priority. This is entirely legitimate, in that the work of an individual should result in their conceptual inclusive fitness increasing. This is a term taken from David Hull’s evolutionary account of science, and refers to the amount of cited use that a scientist’s work receives. It is, in effect, imputed credit. Priority of discovery is supplemented by priority of naming; whose terminology is used is an indicator of the standing a scientist has in their discipline. Attempts to take away naming rights can rest on priority disputes, both in terms of claiming priority for someone else, but also as attempts to deprecate the work of a rival within a competing group or tradition.

Names are not, in themselves, natural facts. If what they denote are natural objects, then nomenclature is critical in classification; otherwise it really is a conventional matter. So the issue is not are the names right, the issue is whether or not they unambiguously denote facts about the world. And here another core problem arises. As Leibniz wrote, paraphrasing Locke (Philolethes is Locke, Theophilus is Leibniz):

PHIL. §25. Languages were established before sciences, and things were put into species by ignorant and illiterate people.

THEO. This is true, but the people who study a subject-matter correct popular notions. Assayers have found precise methods for identifying and separating metals, botanists have marvelously extended our knowledge of plants, and experiments have been made on insects that have given us new routes into the knowledge of animals. However, we are still far short of halfway along our journey.†

Vernacular terms like “ape”, “bird” and “tree” get a major revision by technical science. Some terms, like “mountain” or “jade” can be dissolved either into many technical terms, or spread ambiguously across terms of art in ways that make them scientifically meaningless. When the claim is made in the popular press that “birds are dinosaurs” or “humans are apes”, there is a vernacular sense in which this is simply false. Every child knows that dinosaurs are flightless things with no fur that lived more than 65 million years ago (unless they are well educated into the arcane debates in paleontology; never underestimate a motivated ten year old), so how can birds be dinosaurs? The answer is, of course, that modern phylogenies (classifications based on shared traits that are thought to be the result of evolutionary history) place Aves, the taxonomic name for birds, squarely inside the group Dinosauria, and so by the rules of technical biological nomenclature birds (Aves) “are” (fall inside) dinosaurs (Dinosauria). But this is not how vernacular classifications work. Folk taxonomy is hardly rigorous, and since the words often preceded the science, a degree of revision based on science is inevitable. The technical name “dinosaur” itself entered the English language after they were named in 1842 by Richard Owen. So the claim that birds are dinosaurs is a case of a folk taxonomic term (one that agrees closely with scientific usage) being subsumed under a technical term. The claim that humans are apes is less clear. In folk taxonomy, “ape” is a term that has no comparable scientific meaning. It basically means any primate that lacks a tail and is not human.††

Human, however, denotes a single and scientifically accepted species, so here the claim is that the technical taxon falls within a folk taxonomic category. This is not new, of course, since Linnaeus famously placed humans (Homo) within the same genus as other apes, a classification that was later changed to reflect folk taxonomic preferences. Now, the claim is that humans (Homo sapiens) are apes (Hominoidea), which is a group defined as the African Great Apes. In short, it is a claim that humans are a species of African Great Ape.

Folk taxonomies are not always vague or socially determined. When the objects being classified are things that the language users need to be accurate about, because they hunt, farm or otherwise employ them, folk taxonomies can be quite exact and natural. Mayr famously recounted that out of 137 species of bird “European naturalists” (i.e., Mayr) identified, the tribe in the Foré Mountains of Papua New Guinea that he was visiting identified 136, and the one they disputed was also disputable in western taxonomy**. However, when Edward O. Wilson repeated the question about ants on the Huon Peninsula, he had less success, basically getting only “big ones, black ones” and so on. The reason appears to be that locals must know birds well if they are to find and hunt and eat them, whereas ants are rarely of economic significance.*** So folk taxonomies do not carry much weight when addressing natural classification, but neither should they be deprecated.

* The massive literature on names in philosophy is, we believe, largely irrelevant to the nomenclature problem in the natural sciences, for whatever solution one adopts, either an epistemic referential account, or a historical referential (“baptismal”) account, will turn out to be true of all names in science anyway. However, in practice, names in the historical sciences, and particularly the biological sciences, tend to be baptismal names, applied to a holotype (‘type specimen”), and they thereafter remain unchanged no matter how the definite descriptions change.

† Leibniz, Gottfried Wilhelm. 1996. New Essays on Human Understanding. Translated by P. Remnant and J. Bennett. Cambridge UK: Cambridge University Press. Original edition, 1765: 319.

†† Barbary “apes”, which are macaque monkeys, do have stubby tails. The name was given before clarity appeared even in the folk taxonomy.

** Mayr, Ernst. 1969. The biological meaning of species. Biological Journal of the Linnean Society 1 (3):311-320, page 313.

*** See Diamond, Jared M. 1966. Zoological Classification System of a Primitive People. Science 151 (3714):1102-1104.