Classification by discipline

The DDC is a general classification system which aims to map subjects and classify documents of all kinds falling in any knowledge domain. But there is no absolute or universally accepted structure of knowledge. The DDC places a document in one of the three great Baconian divisions of knowledge, namely reason or science (100–600), imagination (700–800) and memory (900). These three great divisions are divided into nine main areas of knowledge that are themselves divided into disciplines or sub-disciplines (Maltby, 1975, 129).1 This division of knowledge into nine main classes mirrors the educational consensus prevailing the late 19th-century Western academic world. The DDC thus scatters subjects by discipline and the subjects are subordinated to discipline. A subject may occur in almost any discipline. For example, the subject ‘children’ may turn up in library science, psychology, religion, labor economics, education, home management, literature, sports, or arts, etc. and may appear several times within the same discipline. Thus, there is theoretically no single class number for the subject. To solve such situations, the DDC provides an interdisciplinary number for many topics. For example, under 305.23 [sociology of] Young people, there is a note ‘Class here interdisciplinary works on children’. So a book dealing with many aspects of children will class at 305.23.

A discipline is a broad but somewhat coherent area of knowledge, characterized by near-similarity of subject matters or the application of the same research methods in its subfields. A discipline provides context for a subject. John Comaromi wrote (1983, 142–3) that ‘using disciplines to define main classes was a widely used practice in the nineteenth century. It is not surprising that the DDC was conceived as a discipline-based system.’ It does not mean, however, that we cannot collocate the various disciplines dealing with a single subject; this is easily done through the Relative Index and the notes in the schedules frequently provide a single class number for a multidisciplinary topic or a document dealing comprehensively with a subject. The Relative Index reverses the approach of classification by discipline, visually bringing together distributed or scattered aspects of a topic. However, there are several exceptions to the order of discipline–subject subordination. It is wisely said that classification by discipline is good in itself only when not carried to extremes.