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Dewey decimal classification system

Dewey Decimal Classification system

Embarking on a journey to an unknown country without a guide and a compass may lead to exciting or highly disappointing experiences.

In a library, you can leaf through a fashion magazine, skim the back cover of a detective novel or read a few pages of an encyclopaedia article on funeral rites in ancient Egypt. However, if you are looking for the latest novel by a particular author, a recipe for cookies, advice on how to train your hamster or the name of the greatest explorer in medieval China, would you search the shelves haphazardly?

How would you go about it? It would seem quite a challenging task until you realized that the books in a library are arranged according to a standardized classification system used throughout the world. You would simply have to become familiar with this system, and the doors of all school and public libraries would be open to you.

In 1873, an American librarian named Melvil Dewey devised this classification system to make it possible to quickly find any library document he needed. Melvil Dewey therefore created a classification system consisting of 10 main classes divided into 100 divisions and 1 000 subdivisions. The Dewey Decimal Classification system is not perfect, but a team of librarians update it on a regular basis so that it reflects the advancement of knowledge.

The 21st edition is currently being used in libraries and reference centres.

The advantages of the Dewey Decimal Classification system

The Dewey Decimal Classification system is universal because of its numerical notation. Since there are different alphabets, a system based on arabic numerals is used throughout the world.

Documents are classified by subject. Those interested or specialized in a particular topic can find all the documents they need under the same classification.

Three easily overcome disadvantages of the Dewey Decimal Classification system

  1. Classification by subject and not by topic

    For example, the topic of drug use is discussed in psychology (157), sociology (363.45) and medical (616.863) books. Three disciplines deal with the this topic in their own way. Books on drug use can therefore have different call numbers under the Dewey system.
    Nonetheless, an alphabetic catalogue of topics (used in both computerized and non-computerized libraries) makes it possible to locate these books.

    A reader who needs information on drug use (or any other topic) will consult the subject catalogue or the subject heading in a library and documentation centre management software program. He or she will obtain a list of all the books that deal with drug use, regardless of the disciplinary angle from which it is studied.

  2. The same topic can be studied within two different disciplines 

    Let’s go back to the example of books on drug use. If a group of authors publishes a book on all the aspects of drug use, this book cannot be stored in three different places. In this case, the librarian assigning the call number will determine under which subject the book will be classified.

    Again, if the reader consults the subject catalogue or the subject heading in a library management program, he or she will obtain a list of all the books that deal with drug use, regardless of the disciplinary angle from which it is studied.

  3. The length and complexity of call numbers discourages some users

    The Dewey call number can be regarded as an address. If I have to meet Mr. X and I know that he lives at 641 Elm Street, the address tells me where to go. The same is true of the Dewey call number; I don’t need to know whether Mr. X lives alone, or if he has children, a cat or a dog—nor do I need to understand all the intellectual criteria librarians use to determine if a book is to be classified under such and such a call number.

    With regard to the length of the call numbers, remember that elementary and even secondary school libraries use the abridged Dewey Decimal Classification system (no more than 3 digits after the decimal point) to simplify the classification.

    Difficulties often arise when books are arranged by people who do not understand the decimal system. This is now less of a problem for students since decimal notation is a compulsory topic in elementary Cycle Two mathematics under the Québec Education Program.

    Lastly, to facilitate access to books even more, most school libraries have decided not to use the 800 class (literature), which categorizes works by genre, era and country. Literary works (e.g. novels, albums) are therefore simply stored under the letter F (for fiction) and then subdivided by the names of authors listed in alphabetical order.

    You no longer need to rack your brains to determine whether an author’s book is stacked by collection or publisher or to refer to a multitude colour codes to find a popular author.

Concrete example

If you are looking for a cookie recipe, you can always ask Aunt Emily, but if you want to find it in the library, here’s how:

  • Type the word cookies in the subject index of the library and documentation centre management software program. (If the library is not computerized, consult the subject catalogue.) 
  • If the library has documents on this subject, a list of titles will appear on screen.  
  • You will see the Dewey call number (641.865 4) in the lower lefthand corner of the entry.
  • Now go to section 600 (after class 500 and before class 700). You will see 641 and then, after the decimal point, go digit by digit until your reach 641.865 4.
  • You have found the “address” for your recipe book, and now you need only consult its index or table of contents.
  • The book is sure to contain the information you are looking for. It’s now up to you to use it to bake up a storm!

For the more daring, let’s have a look at the structure of the Dewey Decimal Classification system!