Hossein Jorjani
First publication: 2026 – 09 – 12
Classifications are tools for organizing and understanding reality. They should not be confused with intrinsic properties of the things being classified. Reality provides the objects, processes, similarities, differences, and relationships with which classifications must contend, but the boundaries of our categories depend upon the criteria by which we organize them and, often, upon the purposes for which the classification is constructed.
Biological taxonomy provides familiar examples. The taxonomic position of humans in relation to the other great apes has changed during the history of biological classification. The genus Homo has sometimes been divided into more species and sometimes fewer. The relationship between modern humans and Neanderthals has likewise permitted different classifications: Neanderthals may be treated as Homo neanderthalensis or, under another taxonomic interpretation, as Homo sapiens neanderthalensis. Such changes do not alter the organisms or their evolutionary history. They alter the way observed differences and relationships are organized into taxonomic categories.
Pluto provides an even simpler example. Pluto was once classified as a planet and is now classified as a dwarf planet. Pluto itself did not undergo a corresponding physical transformation. Its orbit, mass, composition, and other properties did not suddenly change when its classification changed. What changed were the criteria used to determine membership in the category “planet.” Pluto crossed a conceptual boundary because the boundary was redrawn.
The same problem appears outside the natural sciences. Consider the category “worker.” In one historical or theoretical context, the paradigmatic worker may be the industrial labourer on an assembly line. In another, the term readily includes someone preparing food in a McDonald’s kitchen. Different economic, sociological, legal, or political questions may require somewhat different criteria for deciding who belongs to the category. The people and their activities are real, but the classificatory boundary is constructed for particular purposes.
This does not mean that classifications are arbitrary. Reality constrains them. A biological classification that disregards relevant biological relationships, or an astronomical classification that ignores the properties of astronomical bodies, may be inadequate for its intended purpose. The fact that we construct categories does not imply that we are free to classify things however we please.
It does mean, however, that different legitimate classifications may sometimes be constructed from the same reality. A classification selects certain properties or relationships as relevant and establishes criteria according to which cases are grouped or separated. Different purposes may make different properties relevant. The resulting boundaries may therefore be approximate, revisable, or disputed without implying that the underlying reality is itself arbitrary.
This distinction is especially important when classifications change. A revised classification does not necessarily mean that earlier observations were false. Sometimes new evidence has appeared. But sometimes the evidence remains substantially the same while the criteria, purposes, or conceptual organization change. What has moved is not the object but the boundary of the category.
A classification should therefore be judged by how adequately it organizes relevant features of reality for the purpose for which it is constructed. We should neither mistake our categories for intrinsic divisions of reality nor conclude that, because categories are constructed, reality places no constraints upon them.
The map may be redrawn without the territory having changed.
Hossein Jorjani 