Biology The categorisation and naming of a particular species should be regarded as a
hypothesis about the
evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be confirmed or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual
organisms later identified as the same species. When two named species are agreed to be of the same species, the older species name is almost always retained dropping the newer species name honouring a convention known as "priority of nomenclature". This form of lumping is technically called synonymisation. Dividing a taxon into multiple, often new, taxa is called splitting. Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognizing differences or commonalities between organisms. For example, the number of
genera used in
Pteridophyte Phylogeny Group I (PPG I) has proved controversial. PPG I uses 18
lycophyte and 319
fern genera. The earlier system put forward by Smith et al. (2006) had suggested a range of 274 to 312 genera for ferns alone. By contrast, the system of Christenhusz & Chase (2014) used 5 lycophyte and about 212 fern genera. The number of fern genera was further reduced to 207 in a subsequent publication. Defending PPG I, Schuettpelz et al. (2018) argue that the larger number of genera is a result of "the gradual accumulation of new collections and new data" and hence "a greater appreciation of fern diversity and ... an improved ability to distinguish taxa". They also argue that the number of species per genus in the PPG I system is already higher than in other groups of organisms (about 33 species per genus for ferns as opposed to about 22 species per genus for
angiosperms) and that reducing the number of genera as Christenhusz and Chase propose yields the excessive number of about 50 species per genus for ferns. In response, Christenhusz and Chase (2018) argue that the excessive splitting of genera destabilises the usage of names and will lead to greater instability in future, and that the highly split genera have few if any characters that can be used to recognise them, making identification difficult, even to generic level. They further argue that comparing numbers of species per genus in different groups is "fundamentally meaningless".
Language classification linguistics conference bringing together various prominent Russian "lumpers" belonging to the
Moscow School of Comparative Linguistics, including
Vladimir Dybo and
Georgiy Starostin (standing in front) There is no agreement among
historical linguists about what amount of evidence is needed for two languages to be safely classified in the same
language family. For this reason, many proposed language families have had lumper–splitter controversies, including
Altaic,
Pama–Nyungan,
Nilo-Saharan, and most of the larger
families of the Americas. At a completely different level, the splitting of a
mutually intelligible dialect continuum into different languages, or lumping them into one, is also an issue that continually comes up, though the consensus in contemporary linguistics is that there is no completely objective way to settle the question. Splitters regard the
comparative method (meaning not comparison in general, but only reconstruction of a common ancestor or
protolanguage) as the only valid proof of kinship, and consider
genetic relatedness to be the question of interest. American linguists of recent decades tend to be splitters. Lumpers are more willing to admit techniques like
mass lexical comparison or
lexicostatistics, and mass typological comparison, and to tolerate the uncertainty of whether relationships found by these methods are the result of
linguistic divergence (descent from common ancestor) or
language convergence (borrowing). Much long-range comparison work has been from Russian linguists belonging to the
Moscow School of Comparative Linguistics, most notably
Vladislav Illich-Svitych and
Sergei Starostin. In the United States,
Greenberg and
Ruhlen's work has been met with little acceptance from linguists. Earlier American linguists like
Morris Swadesh and
Edward Sapir also pursued large-scale classifications like
Sapir's 1929 scheme for the Americas, accompanied by controversy similar to that today.
Religious studies Paul F. Bradshaw suggests that the same principles of lumping and splitting apply to the study of early Christian
liturgy. Lumpers, who tend to predominate in this field, try to find a single line of successive texts from the
apostolic age to the fourth century (and later). Splitters see many parallel and overlapping strands which intermingle and flow apart so that there is not a single coherent path in the development of liturgical texts. Liturgical texts must not be taken solely at face value; often there are hidden agendas in texts. The idea of a single Hindu religion is essentially a lumper's concept, sometimes also known as
Smartism (on the basis of the Smārta synthesis). Hindu splitters, and individual adherents, often identify themselves on the other hand as adherents of a religion such as
Shaivism,
Vaishnavism, or
Shaktism, according to which deity they believe to be the supreme creator of the universe. Various
"holistic" approaches to religion can prioritise themes such as individual spirituality, the
New-Age-style essential oneness of multiple religious traditions, or
religious fundamentalism.
Philosophy Physicist and philosophy writer
Freeman Dyson has suggested that one can broadly, if over-simplistically, divide "observers of the philosophical scene" into splitters and lumpers – roughly corresponding to
materialists (who imagine the world as divided into atoms) and
Platonists (who regard the world as made up of ideas).
Psychiatry In
psychiatry, the 'splitters' and the 'lumpers' have fundamentally different approaches to psychiatric diagnosis and classification. First, 'splitters' emphasise the heterogeneity within the diagnostic categories and argue that this heterogeneity drives the 'splitting' process'. 'Lumpers', on the other hand, point to the similarities
between the diagnostic categories, and suggest that these similarities justify the creation of broader entities. Thus lumpers might see
"stress" where splitters could identify (say)
worry,
grief, or some sort of
anxiety disorder.
Neuroscience In neuroscience, "uncertainty aversion" and "uncertainty tolerance" in semantic representations appear to correlate with the terms "splitters" and "lumpers" respectively. As neuroscientist Marc-Lluís Vives observes:Our survival is possible because every day we make use of previously acquired categories to navigate the world. Every single mug we encounter is distinct, but fundamentally the same. Thanks to this powerful capacity to classify distinct stimuli under the same category, we can generalize our knowledge from the previously encountered subset of mugs to a future subset of mugs. However, this also posits a dilemma: Is a glass mug still a mug? That is, what are the defining principles that make something a "mug"? Establishing this is fundamental since it also affects its relationship with its close-neighbors. Conceptualizing a mug as very different from a glass creates a more clear-cut mapping between the input—that is, the stimulus perceived—and the output that a person needs to generate—that is, the response, such as drinking coffee. Classical work in cognitive science demonstrates that the more similar two stimuli are, the harder it is to discriminate them and respond with different behavior.
Computational linguistics and natural language processing Different meanings of words can be categorized as
senses (popular as
word-sense disambiguation), and can lead to the characterization of "lumpers" and "splitters". This is closely related to
lexicography, since computational tools such as
Sketch Engine support construction of modern dictionaries.
Sometimes not all the sense distinctions recognised in the dictionary are viewed as salient to the program. WSD researchers tend to be lumpers, not splitters (Dolan, 1994). Similarly, in
natural language processing, algorithmic approaches such as Word2Vec can be used quantify the overlap or distinguish between semantic categories between words. This can provide an understanding of how often the contexts of words overlap or are dissimilar in general usage. == See also ==