My recent discussion on the value of “originalism” has led to some interesting comments from respondents Mickey Mortimer and Mike Taylor. As I respect both of them, but disagree, I will post their comments in full below and respond to them in more detail rather than in comments. This gives me an excuse for yet another non-tooth-related post.First, Mickey Mortimer questions my argument in regards to Brachiosaurus brancai, as such rather than as Giraffatitan brancai.
The latter was proposed by Paul, then supported by Taylor, but I argued on the merits of the assignment for various reasons. Mickey asks about the null hypothesis, by which we presume all hypotheses must spring, either to refute or to support; specifically, a null hypothesis is any hypothesis which we seek to test. Mickey argues that the null hypothesis for systematic assumptions is that all taxa are dissimilar (NH1). Thus, when making arguments about taxonomy, we can separate taxa (and thus provide them names) when they differ. But there is a second hypothesis which we can test, one that is used and that contradicts the former, as long as it is applied in scale: all taxa are the same (NH2). Thus, if all taxa are different, we must find a scale of similarities instead of differences in compiling them into groups.
The problem here is that both are used in systematic work: We split species off, while joining them into families; but we also split families up, while joining families into other higher categories. In a non-Linnaean manner, we simply use new names, or abandon others as less useful (or completely useless); phylogenetic taxonomy presumes assumptions of synonymy among suprageneric taxa through the use of definitions, but otherwise lacks means of assessing division of taxa.
It is my understanding that both hypotheses are used, and for various purposes. NH2 is useful for combining taxa into supraspecific categories, but also for referring specimens to taxa. This assumption is what allows systematists to compile hypodigms from disparate elements, especially when there is little to no overlap among specimens. The systematist attempts to refute this hypothesis by trying to find features that compare well with other taxa, or by lacking similar taxa in the same region or horizon; in failing this, he affirms the specimens must belong to one another. Not that this is correct, but it is in his affirmation. He has failed to falsify this hypothesis.
But NH1 is also used, especially in the recognition of species (rather than the composition of the hypodigm). This is tested by the systematist attempting to refer a specimen to a known quantum, a hypodigm or species complex; failure results in the systematist trying to diagnose a new taxon. Thus I would reject the premise of just one useful null hypothesis. It may be that species systematics can use just one, but it is also arguable that using both is equally justifiable, or both justifiable in a single analysis for different scales.
Second, Mike Taylor makes the following argument:
I reject the notion that nomenclatural judgements should be dictated only by numerical phylogenetic analysis. However much we might wish we could find a purely objective basis for our nomenclature, the simple truth is that we can’t. All our decisions are informed by taste, experience and precedent, and pretending otherwise is fantasy.
This responds to a comment I made responding to Mickey, where I wrote:
Arguments previous standing were “taste” or “art” reasons, such as naming a new genus because the author thinks it is distinct enough, not justified through discriminate analysis.
Numerical phylogenetic analysis is not the only form of discriminate analysis, just one of the more prevalent forms. It does have a tendency of being used a lot, but I have argued that phylogenetic analysis is only a part of systematics, never its predicate. It is a tool, not the whole. Thus Mike is narrowing my use of “discriminate” to “numerical phylogenetic” with little justification. I recognize a lot of systematic analysis and valid taxa that have not be justified through phylogenetic analysis, and am certain that its use (such as Brontomerus mcintoshi) will continue.
But, there’s more.
When arguing about “taste,” why do we insist on a particular brand of “taste”? How do we quantify — or even qualify — “taste”? I argue we cannot.
Taxonomy is, in one way, a scientific, and rather logical practice: It facilitates communication. Communication in language, for which precision is an ideal, asks us to be able to use the same words for the same objects. And even though it evolves, language enforces terminology and structure. This includes the words for nouns and proper nouns. When labelling a specimen, we use a noun (the specimen number) coupled with a field id number which are unique to it. Intrinstically, this allows immediate understanding that no other object has this label, or complex of labels — this is accessional (or repository) nomenclature. The same is then true for taxonomic rather than accessional nomenclature, where a label implies a systematic rather than repositorial utility. In this case, each of these labels has a logical and scientific function. The most that “taste” gets thrown into this discussion is what label to use.
For accessioning fossils (or any specimen) a sequential value is used, and some institutions use different systems (the AMNH uses numeric succession when reposited, the RTMP uses a date, locality, and specimen when reposited in combination: AMNH FR 6517 [American Museum of Natural History, Fosill Reptiles Collection, reposited sequence 6517]; RTMP 79.20.1 [Royal Tyrell Museum of Palaeontology, collected in 1979, at site 20, first specimen]. This is logical, and the numbers of future accessioning can be predicted, and of the past inferred.
Not so taxonomy, if “taste” rules. No one can object to me making up new nomenclature, in a “taste” world, where sensibility is not qualifiable, where reason has no place.
“Taste” is useful when we want to name things, providing a context to a place, a person, or another taxon. It can be a joke, a pun, a logic puzzle, etc. (most of these up to date are catalogued at the Curiosities of Biological Nomenclature, and the list extends even to gene names). “Taste” is less useful when we want to assess anything, as “taste” becomes a blatant bias in big-s Science. It also leads to people “feeling” that taxa are “more different” than others, largely because of the perceived value of a character; the value of a character over another two or three chatacters; the location of the species in space or time; and even simply by the relative value of how much material is being used to support taxonomy. It can result in synonymy or rejection of synonymy, and often for the same reasons. And if the same argument can merely be inverted to argue for its opposite, we get a purely unscientific principle. That is “taste.”
“Taste” is art, and nomenclature is both; taxonomy and systematics is Science, and should not involve “taste” in any way. That is my argument. Because of this, without any value associated with the distinction between use of “Brachiosaurus brancai” and “Giraffatitan brancai,” I choose to use the form that appeared first. This involves the value of the “genus” (which is a category without scientific definition) with respect to a species (which has been [frequently] defined), and don’t think that those who erected or supported the use of Giraffatitan care, ignoring the qualification question while arguing against those that chose not to use this (optional) nomenclature.