In Steps to an Ecology of Mind, Gregory Bateson includes “Form, Substance, and Difference,” his lecture to the Institute of General Semantics. The Institute promotes the theories of Alfred Korzybski, best known for the idea that the map is not the territory. Bateson carries this metaphor to the next level with his own theory that “information is a difference that makes a difference.” Features on a map are features of difference. A town is different from a road which is different from an elevation. Together they define the territory that the map represents. Together they define a similarity.
Like a map, taxonomy describes differences within similarities. Taxonomy construction analyzes concepts and their ecological relation to each other and to the domain. Within the domain are the differences that make a difference. They are the smaller units of knowledge, each with its own ecology. The resulting hierarchy describes the relationship of the units in a clear display of similarities and differences.
In his lecture, Bateson refers to Immanuel Kant’s idea “that the most elementary assertive act is the selection of a fact.” Kant used the example of a piece of chalk and Bateson amplifies the example, saying “there is an infinite number of differences around and within the piece of chalk. There are differences between the chalk and the rest of the universe, between the chalk and the sun or the moon.”
A primary skill of taxonomy construction is the selection of the differences that make a difference. All domains contain infinite differences, so the taxonomist selects those that the user values. A chalk taxonomy probably would not mention the moon, even though there is a clear difference between the moon and a piece of chalk. Domain knowledge and client knowledge are keys here, along with a talent for designing organizational structures. If selecting a fact is the most elementary assertive act, placing that fact within the context of other facts is more advanced and equally assertive.