The purpose of this paper is to clarify the ontological and epistemological basis of classification.
Attention is drawn to a 1785 article on abstraction by Thomas Reid and the contents and theories of the article are explained. The Reid article both provides a sound approach to classification and is interesting historically as it influenced the classification pioneer Charles Ammi Cutter who, in turn, is responsible for much of the modern theory of functional bibliography. Reid's account is supplemented by brief descriptions of fallibilism and fuzziness. An associated view, Aristotelian essentialism is explained and criticized. Some observations are offered on the role of prototypes in classification and on the monothetic‐polythetic distinction.
Reid's theories, suitably embedded in fallibilism and augmented with a respect for truth, provide a sound ontological and epistemological basis for classification.
Reid's essay, together with an appreciation of fallibility and determinate and indeterminate properties, amount to a good basic theoretical foundation for cataloging.
