Inherent Bias in Classification Systems

December 10th is Dewey Decimal System Day. Maybe it’s only librarians who care much about it but to us it’s a big deal.

The entire history of our profession has been a quest to organize information. Sometimes organizational schemas were focused on preserving resources, on merely keeping a list of a collection’s holding, and sometimes systems were intended to restrict access. Indeed, for most of our history, knowledge institutions were exclusive and exclusionary.

But beginning with the birth of public libraries in the 1800s, we conceived the idea that knowledge should be accessible for the betterment of all people. The challenge was—and continues to be—to find ways to accomplish this goal through practical application in real-world situations, in day-to-day activities.

Melvil Dewey’s system was a massive paradigm shift. It seems like such an esoteric thing to celebrate but realize this: before Dewey’s organizational scheme, there existed no universal method for organizing collections of materials, and too many systems were obscure and overly complicated, to the point where people were often discouraged from attempting to access them.

Dewey created a system that anyone could understand and use. For the first time, people could walk into a library and find what they wanted on the shelf, or explore the catalog, without the mediation of a specialist. In a real sense, the Dewey system effectively transferred our collections of knowledge out of the hands of specialists and into the hands of the general populace. *

Still, for all my appreciation and admiration of Dewey’s achievement, when a coworker asked if I wanted to participate in Dewey Day activities at my library, my response was this:

“I have no interest in celebrating the Dewey system. It’s an archaic monument to Western superiority and colonial oppression which obscures the diversity of human cultures and silences diverse voices.”

I overstated my position for comic effect. However, my coworker had never heard this about the Dewey Decimal System and asked me to elaborate.

I first encountered this criticism in graduate school. I recall reading an essay written by Wayne Wiegand about Western cultural bias in Dewey which was revelatory. I can no longer find an active link to it online. It’s linked to in the post below but the link is broken. This post offers its own concise summary of the problem:

Why Dewey’s Decimal System is prejudiced” from the Journal of the Hyperlinked Organization (September 3, 2004)

Dewey’s classification system was a product of its time and deeply embedded in the worldview of 19th century America. It was an era of a belief in Universal Reason, with European and American intellectuals across all disciplines attempting to categorize all knowledge. That’s the basis of his classification system: he sought a practical application of this ideal.

But 19th century ideas of how the world worked were skewed. Their baseline for what was considered both normal and important was Western, Christian, and male. The foundational structure of Dewey strongly prioritizes Western culture, concerns, and traditional identities.

To explore all the Western biases inherent in the ideal of Universal Reason would be a career’s worth of research and writing. Suffice it to quote this line from Intellectual Activism in Knowledge Organization by Lee Hur-Li (National Taiwan University Press, 2016):

“Western bias, for example, dictates classification to have mutually exclusive categories, a hierarchical structure, a linear sequence… such principles are often at odds with thinking in non-Western cultures.” (p. 30)

The structure of knowledge described here—the structure of knowledge encoded in Dewey’s decimals—is an embodiment the Western ideal of Universal Reason, a product of the 19th Century, wrestling with the legacy of the 17th Century Enlightenment, seeking to build a better society based on the ideals of reason laid out by the Classical Greeks, as reinterpreted and Christianized by the European Renaissance. This structure of knowledge is built into the deepest DNA of Western culture.

Other cultures don’t do things this way. Other cultures don’t approach knowledge with the same assumptions or distinctions. Western classification systems de facto misrepresent the way non-Western cultures view and understand the world. This is something I’ve encountered time and again when I try to reorganize my own books at home: I have a sense that it’s unfair to separate fiction by region or culture (Western, Chinese, African, etc.) or to separate philosophy based on cultural origin, etc. These works are all products of people seeking to tell stories and understand the world. They should be granted equal footing on my shelves on that basis alone.

But every time, I find that I have to separate works by country, culture, or region because these things don’t fit together in a single classification scheme. For example: from the very beginning of Western culture, the Western world made a clear distinction between physics and metaphysics. It recognizes a difference between philosophy and theology. Etc.

By contrast, China didn’t necessarily make those same distinctions: their religions are as much what Europe would call philosophy as religion. In fact, they’re neither—Chinese religions and philosophies are their own thing, independent of Western classifications, for which we have no fully accurate classifications. Likewise, they don’t separate physics from metaphysics as we do: they have different criteria for organizing their world. So when we shelve Chinese works on Western shelves, we jam them into our Dewey-based classifications however seems best to us and it’s always an ill-fit. It necessarily misclassifies them. It de facto fails to accurately represent how they make sense of the world.

There’s also the fact that decimal classification systems are limited in their extensibility—there are only so many numbers to go around. Adding new fields of information, or reevaluating the position and scope of existing fields, requires tremendous disruption.

Every time you classify something, you have to make a judgement call about where it fits and how prominent it should be. People are biased. Any classification system can’t avoid being biased in favor of the culture and identity of the people who created it, and who maintain it.

It’s our job, our mission, to provide access to information and that requires systems of organization and access.

We need to be aware of what’s being left out or obscured by the organizational structures we employ. We need to understand when these systems misrepresent and get in the way of the information needs of various members of our communities.


If you’re interested in diving into this topic, here are some excellent resources to get started:

Classification, Bias, and American Indian Materials” by Holly Tomren (PDF). (From the AILA Subject Access and Classification Committee wiki, 2004). The first paragraph of the introduction is an excellent summary of bias in cataloging systems in general. The Library of Congress Classification System was built off of the Dewey Decimal System, and Dewey’s work influenced the development of all significant modern subject vocabularies used in the United States.

After I read Dr. Wiegand’s essay in grad school, I did more research and discovered a work titled Decimal Classification System: A Bibliography of the Period, 1876-1994 by Sushma Gupta (M.D. Publications Pvt. Ltd., 1997). It’s a bit out-of-date at this point but there are several citations starting the ’60s and ’70s, through the ’90s, which address this issue. If you want to dive in, this is an excellent place to start.

More recently, I was delighted to discover a critical exploration of the practical effects of classification bias in a work about historical food culture: Dethroning the Deceitful Pork Chop: Rethinking African American Foodways edited by Jennifer Jensen Wallach (University of Arkansas Press, 2015). The section beginning with the last paragraph of page 70 through page 71 is worth reading.

The full paragraph in Intellectual Activism in Knowledge Organization which I quoted above is about as good a summary as I’ve found:

Social influences on knowledge organization systems may be seen as rather problematic at times. Since the 1970s, a sizable number of studies have been conducted that expose the social and cultural biases in existing mainstream bibliographic classifications such as the Dewey Decimal Classification. It is suggested that bias often causes difficulties or creates barriers in information seeking for affected users. Bias may appear in the content of a classification in the forms of omission of certain topics (e.g., a gender) and inadequate space allocation to a topic (e.g., many non-Christian religions lumped into an “other” category). By the same token, bias may manifest in the structure of a classification scheme. Western bias, for example, dictates classification to have mutually exclusive categories, a hierarchical structure, and a linear sequence of subcategories within a category (e.g., from abstract to concrete); such principles are often at odds with thinking in non-Western cultures. (pp. 29-30)

So, it’s a lot to chew on. And these are just a very few of the many works available which explore classification system biases. It’s worth exploring, though.


* Specifically, literate and at least partially educated people.


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