The Dewey Decimal Classification System

Melvil Dewey was one of the great intellectual giants of his time.  One of his awesome inventions that I’ve been recently studying is the Dewey Decimal Classification System.  Dewey first began developing the DDCS in 1873 while he was working at the Amherst College library and finally published its first version in 1876.  Over time, the proprietary system has slowly evolved and is currently maintained and licensed out to small libraries by the OCLC; the latest revision of the DDCS was released in 2011.  Today, the Dewey Decimal Classification System is used in more than 200,000 libraries in over 135 countries.

The DDCS fascinates me because it represents one man’s vision of how all of human knowledge should be mapped out.  In the DDCS, knowledge is organized into ten divisions:

  • Class 000:  Computer Science, Information, and General Works
  • Class 100:  Philosophy & Psychology
  • Class 200:  Religion
  • Class 300:  Social Sciences
  • Class 400:  Language
  • Class 500:  Science
  • Class 600:  Technology
  • Class 700:  Arts & Recreation
  • Class 800:  Literature
  • Class 900:  History & Geography

Then each division is further organized into more granular subdivisions.  For example:  “010” corresponds to “Bibliographies” and “790” corresponds to “Sports, Games, & Entertainment.”  For instance, if you were trying to search for a book on “Tom Hanks,” it’d likely be classified in 791 (“Public Performances”).

Building on Dewey’s work, I feel like I can adopt his DDC system when I build my own ontology of Wobble2.  Online, I found some great work by Cameron Mence who has used the D3 library to build this nifty tree map that represents a subset of how books are distributed in the DDCS.

Of course, whenever you start trying to develop meta-level schemas, taxonomies, and ontologies to organize all of human knowledge, you’re going to import your own biases into the project.  If you’re a human being, it’s simply impossible to be unbiased.  Thus, the DDCS has sustained its fair share of criticism over the centuries since its inception.  Times change and the world around us, and how we understand it, likewise evolves.  A great example:  In 1932, topics related to “homosexuality” were initially added under 132 (“mental derangements”) and 159.9 (“abnormal psychology”).  In 1932, that’s simply how humans (or at least, the humans in power who organized libraries) viewed the world.  But what’s fascinating is watching how human knowledge progressed and evolvedBy 1952, “homosexuality” was added to the 301.424 range (“the study of sexes in society”) and in 1989 was added to 363.49 (“social problems”).  It wasn’t until 1996 that it was added to 306.7 (“sexual relations”) which OCLC calls its current “preferred location.”

Finally, I found it fascinating (though, I guess, predictable) that nearly the entire 200 range covering “religion” is actually just all about “Christianity.”  Amusingly, all of the world’s thousands of other religions (for example, including Islam– a pretty big one at 24.1% vs 31.2% of Christianity, globally) are relegated to just a narrow band inside the 290s.   Christianity occupies everything else in the 200s!

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