Pierre Duhem on Classification - Dictionary of Arguments
Classification/Duhem: What is natural classification? Context of mental operations. It treats not concrete individuals, but abstractions: the types, e.g. vertebrates.
It explains, for example, that the swimming bubble of the fishes is the same as the lungs of the vertebrates. This is a purely ideal combination, which is not based on real organs but on simplified representations. More or less conspicuous similarities are seen by the zoologist as proof of a kinship.
If, on the other hand, paleontology were to explain to him that the kinship did not exist in this, the zoologist would nevertheless continue to believe that the system was a real relation. He would admit to having deceived himself about the nature of these relationships, but not about their existence._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. Translations: Dictionary of Arguments The note [Author1]Vs[Author2] or [Author]Vs[term] is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.
La théorie physique, son objet et sa structure, Paris 1906
Ziel und Struktur der physikalischen Theorien Hamburg 1998