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Libraries attempt to organize and shelve books about the same subject matter together. This may sound simple and rather straightforward; however, if you stop and think for a moment you will realize that most books are about more than one idea or subject. Most books cover a number of different subjects and some books cover two or three subjects in equal depth. But when it comes to placing the book on the shelf the librarian must choose one of the subjects and classify the book under that subject. Whatever decision the librarian makes will have implications for the person seeking the information.
The two major classification systems used in American libraries to organize books on library shelves are the Dewey Decimal Classification System and the Library of Congress Classification System. Both systems organize knowledge into subject categories and allow libraries to shelve similar books together. Dewey is the older of the two systems and is used mostly by public libraries and small academic libraries. The Library of Congress Classification System is used predominately by academic libraries and other libraries that have large research collections. We will start by discussing the Dewey Decimal System which is used to catalog our library's children's collection. The Williams Library uses the Library of Congress Classification System to catalog its main collection.
Dewey Decimal Classification System
The Dewey Decimal Classification System was designed by Melvil Dewey in 1876. Dewey was a librarian who worked in Boston and New York. He was very interested in creating efficient ways to organize knowledge and make it accessible to the public. Prior to Dewey's time there were few public libraries, and patrons were not allowed to go into the book stacks to look for their own books. Books had to be paged for the patron by a library staff person who knew where things were located. Most academic libraries at the time were little more than warehouses. Melvil Dewey worked to change this situation. By developing a uniform way to classify knowledge, Dewey provided libraries with a way to systematize their work. By working to get all libraries to adopt his system Dewey hoped to provide uniform access to knowledge for all patrons. Dewey argued that if all libraries adopted the Decimal Classification System, a library patron could go into any library in the country and expect the books to be arranged in a similar uniform manner. Adoption of the Dewey Decimal Classification System also promoted opening up the book stacks to users because they could now understand how the books were arranged.
The Dewey Decimal Classification System is currently in its 21st edition. As new knowledge and disciplines come into existence, new subject categories have to be created in the system. Sometimes new subject disciplines must be forced to fit into older categories. Remember, the Dewey system was first designed in 1876, long before computers, interstate highways, nuclear power, the space program and the automobile. Each edition of the Dewey Decimal System must retain as much of the original structure as possible. If a new edition of the Dewey Decimal System changed too much it would mean that every library using the system would have to re-catalog its entire collection--and no library has the financial or human resources to accomplish such a task. The Library of Congress Classification System faces similar issues, however, because it has more categories it provides more flexibility for assigning classification numbers.
The Dewey Decimal Classification System divides all the world's knowledge into ten broad categories. Dewey based his subject arrangement of knowledge on the western academic model. As a result, the Dewey Decimal Classification System has a western world view built into the very system itself. This western bias has led to problems in the classification of knowledge from non-western cultures.
The first division of the Dewey Decimal Classification System is referred to as the First Summary, or the Ten Main Classes. The First Summary is further broken down into narrower subdivisions, referred to as the Second Summary. The Second Summary breaks down further, and so on and so on. Each subdivision classifies knowledge into more specific units.
Library of Congress Classification System
The Library of Congress Classification System was developed by the Library of Congress in Washington, DC in the early 1900's to organize the collections of the Library. The Library of Congress chose to develop its own classification system rather than use the Dewey Decimal Classification System because of the large size of its collection--the Dewey system was not considered flexible enough to meet the needs of the LC collection. Over the years most U.S. research and academic libraries, as well as some public libraries, have adopted the Library of Congress Classification System.
The Library of Congress Classification System organizes knowledge into twenty-one broad categories. The twenty-one categories (labeled A to Z, but missing I, O, W, X and Y) are further subdivided by adding one or two additional letters and a set of numbers. The first letter of a Library of Congress call number indicates the general subject area. The second letter indicates the specific subject section within the general category.
The Library of Congress Classification System, unlike the Dewey Decimal Classification System, does not attempt to divide all the world's knowledge into a comprehensive philosophical system. The Library of Congress Classification System is based on the actual books owned by the Library of Congress and attempts to classify those books into meaningful subject categories. When you look at the Library of Congress Classification System you will notice that subdisciplines do not fit neatly within broader areas of knowledge.
In the Dewey System the subjects "Law," "Political Science," and "Economics" are all subclasses of the "Social Sciences." Dewey arranges the subjects this way because it is based on the way western society organizes knowledge. The Dewey system is based on a philosophical system, i.e., a certain way of seeing the world.300 Social Sciences
In the Library of Congress Classification System "Political Science" and "Law" have their own classes and "Economics" is a sub-class of "Social Science and Business." The Library of Congress system is not based on an underlying philosophical system, rather it is organized around pragmatic choices, i.e., the way it works best for the Library of Congress' actual book collection.H: Social Sciences and Business