iSoul In the beginning is reality.

The origin of species terminology

Creationism in a philosophical/scientific context was first propounded by Socrates (David Sedley, Creationism and its Critics in Antiquity, 2007). Socrates did not provide specifics but it is often said that Plato and Aristotle did: biological species were like logical species and so did not change — species were fixed — and purportedly this is what creationists have said ever since. But that is an over-simplification which requires a two-part response: (1) what are species, and (2) what does species fixity mean?

The place to begin is with the book Species: A History of the Idea by John S. Wilkins. The author starts by rejecting what he calls “the Received View” which runs like this:

“Plato defined Form (eidos) as something that had an essence, and Aristotle set up a way of dividing genera (gene) into species (eide) so that each species shared the essence of the genus, and each individual in the species shared the essence of the species. Linnaeus took this idea and made species into constant and essentialistic types. Darwin overcame this essentialism.” p.4

Wilkins shows that the Received View is mistaken. Species have come down to us via a neo-Platonic, not an Aristotelian, route. Typology and essentialism were not bound together. Instead, what he calls the generative conception of species runs through pre-Darwinian thought.

Wilkins distinguishes two kinds of taxonomy: universal, which is classification in general by division, and biological, which is classification by generation. Plato classified things by diairesis (division) and synogage (grouping) according to their differences and similarities. The purpose was to “carve nature at its joints”.

Aristotle broadened Plato into a method that was later called per genus et differentiam — by the general type and the particular difference. For him “a species is a group that is formed by differentiating a prior group formed by a generic concept.” Aristotle accepts only the possibility (not the necessity) that species might be eternal. Similarly, the Epicureans held that “species are forms generated by the natures of their substances.”

In the modern era John Ray in the 17th century was the first to describe biological species. In his 1686 History of plants Ray was the first to produce a biological definition of species:

“… no surer criterion for determining species has occurred to me than the distinguishing features that perpetuate themselves in propagation from seed. Thus, no matter what variations occur in the individuals or the species, if they spring from the seed of one and the same plant, they are accidental variations and not such as to distinguish a species… Animals likewise that differ specifically preserve their distinct species permanently; one species never springs from the seed of another nor vice versa”. (Ernst Mayr, Growth of biological thought, p.256).

Carl Linnaeus ran with this in his Systema Naturae (“The System of Nature”) and other writings. While he later realized the species concept had its limits, it has provided a basis for natural history ever since.

The concept of permanent species came to be known as fixity of species and was the foil for Darwin, who focused on its lack of changeability. For Ray and Linnaeus change was variation that was not part of the species (the type or kind). For Darwin change is evolution which includes each species and more. It’s a question of which came first or is primary: change or type? For evolutionists, change is primary; for Darwin’s predecessors and opponents type is primary.

If type is primary, then the type or kind (which is what the word species means in Latin) is invariant. Science generally looks for and studies invariants such as conservation principles. But biologists after Darwin look for variance instead. That allows them to explain anything and everything as change. It’s a gain in explanatory ability at the cost of invariant principles. There are no laws of evolutionary biology, unless you want to make the non-law “everything is change” a law.

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