Like definition, classification sometimes gets an unjustified bad name. It is not a kind of truth about the world, but rather plays an expressive role, helping to explain the meaning of what is said. Classification makes it possible to substitute simple names for arbitrarily complex conditions or adverbial expressions, allowing the underlying complexity to be abstracted away, or reconstructed as needed.

In Book 1 of Parts of Animals, Aristotle shows great sophistication about this. He explicitly argues against Plato’s recommended procedure of “division” or repeated application of binary distinctions, noting that many significant real-world distinctions are better approached as n-ary or manifold than as binary.

He also explicitly notes how difficult and arbitrary it ends up being to develop real-world classifications in a strictly hierarchical manner, arguing for a more holistic approach, which cannot be reduced to a sequential application of lower-level operations.

Good real-world classifications are arrived at through dialectical trial, error, and iterative self-correction over time. Conversely, behind every ordinary referential use of simple names for things is a complex implicit dialectical/semantic development. (See also Difference; Aristotelian Identity; Substance; Aristotelian Semantics.)