1) The document discusses the concept of "good species" in biology and how it has evolved over time. 2) Historically, the term "good species" was used by botanists in the early 19th century to refer to species that were clearly defined and distinguishable, as biologists were aware of natural variation within species. 3) The concept of a "good species" is now viewed as a prototype or exemplar that competent biologists would agree meets multiple species criteria, rather than having a strict definition. What counts as a good species depends partly on the accepted practices within a specific field of biology.

1. John S Wilkins, ISHPSSB 2021
The Good Species
Building epistemic concepts in science

2. Nor shall I here discuss the various definitions which have been given of the term
species. No one definition has satisfied all naturalists; yet every naturalist knows
vaguely what he means when he speaks of a species. (Darwin 1859, p. 37)
• Pluralism
• Eliminativism
• Conventionalism
• I will propose a professional epistemic notion
of species
• Apprenticeship knowledge
• Experiential knowledge
How are good species conceived?
The acquired knowledge of categories

3. • The term is “good” species or “true” species—e.g., Darwin:
• “When the views advanced by me in this volume, and by Mr. Wallace, or
when analogous views on the origin of species are generally admitted,
we can dimly foresee that there will be a considerable revolution in
natural history. Systematists will be able to pursue their labours as at
present; but they will not be incessantly haunted by the
shadowy doubt whether this or that form be a
true species. This, I feel sure and I speak after experience,
will be no slight relief. The endless disputes whether or
not some fifty species of British brambles
are good species will cease.”
[Origin 1959, p425]
Why do biologists speak of species this way?
A history of Good Species

4. • The phrase “good species” in English seems to have been
adopted widely in botany in the
fi
rst decade of the 19th
century, and it is no coincidence that Darwin uses it in a
botanical context.
• Translated into French and German later.
• It seems to have been required as systematists adopted the
Linnaean “natural system”.
• That such a concept was needed so soon after adopting a
ranked system indicates the fact that naturalists were aware of
the variation within species and genera quite early on, and the
consequent vagueness of many species
The botanical origins of the terms
Good and True

5. I swallowed [my master’s] incidental teachings and
gradually got to know the “good” and “bad” species of
my homeland through a kind of tradition, but I frankly
admit that even then I could not be quite clear how to
accept a given case without tradition and recognise
whether one was dealing with a “good” or a “bad”
species. (Kerner 1866, p. 5)
• Botanist Anton Kerner von Marilaun (1831–1898,
University of Vienna) argued that the term is
learned from the “master” (in an apprenticeship training as a
botanist) and not de
fi
ned
• It is not even clear if practitioners could de
fi
ne good species
• German term gute Arten translated from English
A 19thC German-language discussion
Recognising good species
Source: Wikimedia

6. [T]he concept of good species, a prototype of species,
mediates the non-definitional, or perhaps implicit mode of
understanding of species. A good species is a taxon judged
to be a species according to more than one species
criterion—such as reproductive isolation and phylogenetic properties—or a
taxon judged generally to be a species by competent biologists, whether the
phrase merely expresses one’s epistemic confidence in the taxonomic
judgment or has even an ontological implication that the species category is
divided into good and not-so-good species.
• For some (Amitani) a Good Species is whatever all systematists
would accept as a species, no matter the de
fi
nitions
• Do such things exist? Depends on who is doing the accepting
or not
Good species as exemplars
Amitani’s prototype
Yuichi Amitani, University of Aizu,
Aizuwakamatsu, Japan

7. • Like Kerner, what counts as a good species is in the practical and conceptual criteria used by
leaders in that
fi
eld
• Is the species exclusively sexual?
• Is there introgression?
• Are there strongly marked environmental adaptations?
• What assays can be run on the specimens (e.g., DNA sequence, chemical assays,
vocalisations, etc.)?
• This implies that criteria for good species themselves evolve over time, with advances in
shared knowledge and practices
Practitioners receive the collective wisdom
Good species are disciplinary
The limits of the majority of species are so undefinable that few naturalists are
agreed upon them; to a great extent they are matters of opinion, even amongst
those persons who believe that species are original and immutable creations; and
as our knowledge of the forms and allies of each increases, so do these differences
of opinion; the progress of systematic science being, in short, obviously
unfavourable to the view that most species are limitable by descriptions or
characters, unless large allowances are made for variation. (Hooker 1859, p. iii)

8. • Some terms are theory-based (electron, quantum
fi
eld,
mammal)
• Some terms are developed from practice (organism, genes,
geographical names and types like Sclerophyll or Chaparral)
• Some are ordinary language terms that get introduced into a
science and later re
fi
ned
• Of these, many are replaced by more technically precise
terms (animal ➝ theropod, therapsid, vertebrate, etc.)
• Species is unique as far as I can tell as a vernacular term (in
Latin for “kind”) being invested with more than epistemic status
Vernacular terms that evolve with the work
Operative* terms
* Not operational terms, which are Bridgman’s terms whose meanings are derived by measurement.

9. Naked lobose amoebae are among the most difficult protists to differentiate. Because
they are believed to be agamous (clonal) organisms, the biological species concept,
which involves defining species based on their reproductive isolation, is not applicable.
The general consensus is that for such taxa the morphospecies concept is the only one
practically available. However, analysis of the morphological differences between
amoeboid protists is rather difficult, and conclusions are often unreliable, especially for
closely related species. This is partly because the shape of an amoeba is dynamic; in
stained preparations after fixation and dehydration specimens are often no longer
representative. So, there is no way to preserve a type specimen of an amoeba – a
holotype, so important in traditional biological systematics. Many amoebae species are
culturable, and therefore type strains can be deposited in culture collections. However,
this practice became widely used only after the 1960s and there are still many
examples where strains deposited with the culture collections were lost. So, until the
advent of microphotography, the only tools to document amoebae species were line
drawings and text descriptions, both of which tended to be rather author-specific. For
example, despite careful descriptions provided by E. Penard in his fundamental
monograph published in 1902, and a large number of stained preparations left by him,
many of his ‘species’ are now unrecognizable.
A case study
Lobose amoebas
Smirnov, A., 2009. Amoebas, Lobose. In: M. Schaechter, ed. Encyclopedia of Microbiology (Third Edition). Oxford:
Academic Press, 558–577.
https://www.keweenawalgae.mtu.edu/
gallery_pages/lobose_amoebas.htm

10. • Logical quanti
fi
cation of theories (Logical empiricism, Ramsay
fi
cation
leading to variable kind terms)
• Model development leading to nodes (things) and edge (relations) names
(Nersessian)
• Mechanisms (causal accounts; overlaps with model building)
• Folk terms
• Terms like “mass”, “part”, “kind”, “phenomenon”
• Often treated as unanalysed (e.g., phenomenon) and uncontentious
• Usually replaced over time with “jargon”/technical terms with precise
meanings
• Often ends up in disputes within science (“uniform”, “monophyly”)
Theories, models, mechanisms and folkishisms
Pathways to novel terms in science

11. • Deme
• Gilmour; originally a neutral taxon term
• Evolveron/Phylon
• Reydon
• Least Inclusive Taxonomic Unit
• Pleijel and Rouse
• Lineage
• Simpson, de Queiroz
• Linneon/Jordanon
• `Lotsy
• Metapopulation
• Richard Levins
• Phenon/Operational Taxonomic
Unit
• Sneath & Sokal
• Syngameon
• Lotsy
• Taxon
• Meyer-Abich, but used much earlier
(18thC)
Most remained separate terms or changed meaning
Attempts to replace species

12. • Specialists invest a lot of time and effort in becoming familiar with
the terminology of a discipline
• But with taxonomy, the terminology affects the entire catalogue
of names and terms
• To change the genus name of a group of species is not that costly
• To change the criteria for inclusion is massively costly
• Hence the resistance to alternative taxonomic schemes like
PhyloCode
• In sum, knowledge is based on apprenticed learning, which is
highly conserved
It’s the investment, stupid
Why is species so good?

13. • Each discipline creates its own interpretation of interdisciplinary or
folkish terms
• Disciplines are fractal – each discipline has subdisciplines that have their
own conceptual and terminological constraints
• E.g., Biology includes
• Evolutionary Biology, includes
• Vertebrate evolutionary biology, includes
• Mammalian evolutionary biology, etc.
• Botanical evolutionary biology…
• Hence a term that makes sense in the overarching discipline may have
incommensurable interpretations in subdisciplines
• Species is one such term, and it has a plethora of general and speci
fi
c
meanings.
• And always will.
Polysemy due to independent history of disciplines
Species is purely instrumental

14. Forthcoming in
Species and Beyond,
edited by John Wilkins,
Frank Zachos, and Igor
Pavlinov, to be
published by CRC
Press in 2022
Thanks to Yuichi
Amitani for his seminal
paper: “Prototypical
reasoning about
species and the
species problem.”
Biological Theory,
2015. 10 (4), 289–300.
Image “Abyssal Zone “ by Scott Partridge
jevajeva@yahoo.com