“Ordering Knowledge: Canons for Succession of Characteristics”

When you walk into a library and search for a book on literature, have you ever wondered why books are arranged the way they are? Why does the Dewey Decimal Classification system place literature by language first, then by form, and finally by period? The answer lies in one of the most elegant yet complex principles in library science: the canons for succession of characteristics. These principles determine the order in which different attributes are used to classify and organize information. Understanding this concept transforms how libraries serve their users and how we make sense of vast amounts of knowledge.

Why the sequence of classification characteristics matters 🔗

Classification systems exist to solve a fundamental problem: how do we organize infinite amounts of information so people can find what they need? Simply grouping items together is not enough. The order in which we apply different characteristics-such as language, format, time period, or author-significantly impacts whether a user can easily locate what they’re seeking.

Consider two approaches to organizing literature. If you arrange books first by the author’s birth date, then by genre, users studying a specific literary movement across multiple languages would find it difficult to locate all relevant works. However, if you arrange literature first by language, then by genre, then by period, scholars can systematically explore how poetry developed across a specific language over time. The difference is not in the characteristics used but in their sequence. The success of any classification system depends equally on the skillful selection of characteristics and the order in which they are applied.

This realization emerged from the work of S.R. Ranganathan, a legendary figure in library science. Ranganathan developed a comprehensive framework called the postulational approach to understand how classification systems should function. Within this framework, he introduced the canons for succession of characteristics-three fundamental principles that govern how we should arrange classification characteristics in the correct sequence.

The three canons of succession explained 🔗

The three canons for succession of characteristics form the backbone of how modern classification systems are designed. Each canon addresses a different aspect of how characteristics should be ordered and applied.

Canon of Concomitance 🔗

The Canon of Concomitance states that two different characteristics applied consecutively should not produce the exact same sub-classes. In other words, when you divide a group using one characteristic and then use another characteristic to subdivide further, the second characteristic should actually create new divisions rather than repeating the same groupings as the first.

Here’s a practical example. Imagine you’re classifying students in a college program. If you first divide them by “enrolled in Library Science” and then by “studying Information Science,” you’ve created a problem. Every student who satisfies both characteristics would fall into the same subdivision, making the second division redundant. Instead, you might divide by “academic year” first, then by “specialization.” Now each subdivision produces genuinely new and different groups.

The Canon of Concomitance prevents waste and redundancy in classification. It ensures that each characteristic contributes something meaningful to the organization of knowledge, rather than merely repeating divisions that earlier characteristics already created.

Canon of Relevant Succession 🔗

The Canon of Relevant Succession depends on the purpose of classification. This principle recognizes that there is no single “right” order for characteristics. Instead, the sequence should reflect what serves the majority of users most effectively.

For instance, imagine organizing a collection of novels. You could arrange them by author nationality first, then by publication period, then by genre. Alternatively, you could arrange them by genre first, then by publication period, then by author nationality. Neither sequence is inherently wrong. However, if your library’s users are primarily literature students studying how different genres evolved, the second approach-genre first-would be far more helpful. If your users are scholars examining how different nations contributed to global literature, the first approach would serve them better.

The Canon of Relevant Succession states that the sequence of characteristics must be relevant to the purpose of classification and helpful to the majority of library users. This principle requires classifiers to think deeply about who will use the system and what purposes it should serve. It acknowledges that different users may have different needs, but the system should optimize for the most common and important uses.

Canon of Consistent Succession 🔗

Once you’ve decided on the order of characteristics for a classification system, the Canon of Consistent Succession demands that this sequence must be followed consistently unless the fundamental purpose of classification changes. This principle ensures predictability and reliability within the system.

Think of it as making a promise to users. If you classify History books by region first, then by time period, users learn to expect this order. When they encounter another History section, they’ll instinctively look for the same sequence. If you suddenly switched to time period first and region second, users would become confused and lose faith in the system. By maintaining consistent sequence, you create a mental model that users can rely upon, making navigation intuitive.

How these canons apply to literature classification 🔗

To see these principles in action, let’s examine how modern classification systems actually organize literature. The Dewey Decimal Classification arranges literature successively by language, form (such as poetry or drama), and period. This is not arbitrary. It reflects decisions made by classifiers about what matters most to library users.

Consider a library collection of English literature. Following this sequence, books would be organized like this: First, you’d locate English literature (language characteristic). Next, within English literature, you’d find the specific form-perhaps poetry. Finally, within English poetry, you’d find works from a particular historical period-say, the Romantic era. This arrangement allows a student researching Romantic poetry in English to move methodically from a broader category to increasingly specific divisions.

However, imagine a library that served primarily scholars studying how different poetic forms developed across languages. That library might benefit from organizing literature first by form (poetry, drama, etc.), then by language, then by period. This sequence would serve their users better, reflecting the Canon of Relevant Succession. The characteristics are identical; only the order changes. And as long as that order is maintained consistently throughout the system, the Canon of Consistent Succession is satisfied.

Impact on user experience and findability 🔗

The practical impact of these canons extends directly to how easily library users can find what they need. When classification systems follow these principles, several benefits emerge.

First, maintaining consistency in the succession of characteristics helps users easily navigate the entire classification system. Users can develop mental models of how information is arranged and apply that logic across different subjects. A student who understands that history is organized by geography first and time period second can apply that same logic when looking for books on geology or religion, creating a unified and predictable experience.

Second, following the Canon of Concomitance ensures that the classification system is efficient. Every division created by a new characteristic provides genuinely new information rather than restating earlier divisions. This efficiency means that the classification scheme remains manageable in size and complexity, even when applied to millions of items. Users aren’t lost in redundant or confusing subdivisions.

Third, applying the Canon of Relevant Succession means the system serves actual users rather than abstract ideals. A classification system that orders characteristics by how useful they are to its primary audience transforms from an interesting intellectual exercise into a practical tool. Users find what they need faster, making their research more efficient and productive.

The broader principle in knowledge organization 🔗

These three canons represent something deeper than just rules for arranging books. They embody a philosophy about how human knowledge is best organized for human use. They recognize that classification is not about creating a perfect, universal hierarchy of all knowledge. Rather, it’s about creating systems that serve real people with real information needs.

This approach has influenced how citation order is considered in classification systems, requiring classifiers to determine which characteristics apply to a specific work and the sequence in which facets will be ordered. Modern classification design, whether physical libraries or digital databases, continues to grapple with these questions: Which characteristics matter most? In what order should they be applied? How consistently should we maintain that order?

What do you think? When you search for information online or browse a library, have you noticed how the order of categories affects your ability to find what you need? How would your search experience change if the classification sequence were reversed?

References

1. https://ebooks.inflibnet.ac.in/lisp2/chapter/work-in-the-idea-plane-canons-of-characteristics/
2. https://www.libraryinfoscience.in/2026/02/knowledge-organisation-canons-of.html
3. https://www.oclc.org/content/dam/oclc/dewey/versions/print/intro.pdf
4. https://socialsci.libretexts.org/Courses/Sacramento_City_College/LIBT331:_Library_Cataloging_Procedures_(Li)/01:_Cataloging_Rules_and_Tools/1.4.03:_Introduction_to_the_Dewey_Decimal_Classification