Exploring Definitions and Concepts of Information in Library Sciences

Walk into any discussion about library and information science and you will quickly hit a deceptively simple question: what exactly is “information”? We use the word every day, yet pinning down a precise meaning has occupied some of the sharpest minds in the discipline for over half a century. The challenge is that information is not a single, tidy object. It behaves differently depending on whether you treat it as a thing stored on a shelf, a signal travelling through a wire, or a change happening inside someone’s mind. To make sense of this, scholars have proposed competing definitions and conceptual frameworks, each highlighting a different facet of the phenomenon. This post examines four influential viewpoints that every student of the field should know: Belkin’s user-centred approach, Wersig and Neveling’s six-way classification, Brookes’ fundamental equation, and Machlup’s economic reading of information.

Definition versus concept: why the distinction matters 🔗

Before exploring individual thinkers, it helps to separate two ideas that are often confused. A definition tells you what a word means in a fixed, often dictionary-like way. A concept is broader. It captures how a term functions within a particular field of study, including its purpose, relationships, and the problems it helps solve. Nicholas Belkin, a pioneer of the cognitive view in information science, argued that information science does not necessarily need a watertight universal definition of information. Instead, it needs a working concept that is useful for the discipline’s own goals.

This is a practical position. A physicist, a biologist, and a librarian may each define information differently, and that is fine. What matters for our field is having a concept that supports the central task of connecting people with the knowledge they need. Belkin’s two early contributions to this debate were aptly titled around the “concept” of information in informatics and “towards a definition” of information for information science, signalling that he saw both as connected but distinct projects.

Belkin’s approach: information centred on the user 🔗

Belkin, working with Stephen Robertson, built his understanding of information on a single unifying idea: change of structure. In their 1976 paper on the phenomenon of information, they treated information science as a problem-oriented discipline concerned with the effective transfer of desired information from a human generator to a human user. From this starting point, they proposed that the common thread running through all existing concepts of information is that information is whatever changes the structure of a recipient’s knowledge.

In simple terms, a message becomes information only when it alters what you already know. A weather report you have already heard ten times carries little information for you, even though it carries plenty for someone hearing it fresh. This makes information inherently relative to the receiver. The same text can be rich in information for one person and empty for another. This is why utility, relevance, and the ability to predict are central to Belkin’s thinking. Information is valued not for its own sake but for what it does for the user trying to resolve a situation.

The anomalous state of knowledge 🔗

Belkin’s most famous extension of this idea is the Anomalous State of Knowledge, usually shortened to ASK. The notion is that a person begins searching for information when they recognise a gap or inconsistency in their own knowledge that prevents them from achieving a goal. The user often cannot even specify precisely what they need, because if they could describe it fully, they would already possess the knowledge. This insight helped push the field away from a purely system-centred view toward a user-centred, cognitive paradigm that dominated information retrieval research from the late 1970s onward. The practical implication for libraries and search systems is profound: a good system should help users articulate and resolve their knowledge gaps, not merely match keywords.

Wersig and Neveling’s six approaches to information 🔗

While Belkin sought a single unifying concept, Gernot Wersig and Ulrich Neveling took a wider survey. In their influential 1975 work, they catalogued the many ways scholars had used the word “information” and grouped them into six distinct approaches. Their classification remains one of the clearest maps of the conceptual terrain, and it is frequently cited in reviews of the meaning of information in library and information science.

The structural approach 🔗

Here, information is seen as the structures of the physical world, the static relations between objects, whether or not anyone perceives them. On this view, information exists in the universe independently of human minds. The arrangement of rings in a tree trunk or the pattern of stars carries information simply by being structured, regardless of whether someone reads it.

The knowledge approach 🔗

This approach treats information as knowledge built up through perceiving the structure of the world. The terms information and knowledge are sometimes used interchangeably under this heading, with information understood as what is known about something.

The message approach 🔗

Closely tied to the mathematical theory of communication developed by Claude Shannon, this approach views information as symbols carried by a physical medium. The focus is on signs and signals being transmitted, measured in quantities such as bits, rather than on what those signals mean. This is the engineer’s notion of information.

The meaning approach 🔗

In contrast to the message approach, the meaning approach takes the semantic content of a message as the information. What counts is not the signal itself but the significance a receiver draws from it. Two identical messages can therefore carry different information if they mean different things to different people.

The effect approach 🔗

Also called the recipient-oriented approach, this view holds that information arises as a specific effect within a recipient. Something only becomes information when it produces a change in the person receiving it. This idea overlaps strongly with Belkin’s notion of change of structure and shows how these frameworks intersect rather than stand entirely apart.

The process approach 🔗

Finally, the process approach treats information as an activity rather than an object. Information is the process by which the human mind takes in a problem along with useful data and works toward understanding. Under this reading, “to inform” is a verb, and information is something that happens rather than something that sits still.

Brookes’ fundamental equation of information science 🔗

If Wersig and Neveling mapped the variety of meanings, Bertram Brookes tried to capture the relationship between information and knowledge in a single compact formula. Brookes, a British information scientist at University College London, proposed what is now widely known as the fundamental equation of information science. It is usually written as:

K[S] + ΔI = K[S + ΔS]

The equation reads as follows. A person holds an existing knowledge structure, written as K[S]. When a piece of information, ΔI, is absorbed, it modifies that structure, producing a new knowledge structure, K[S + ΔS]. The term ΔS represents the effect of the modification, the actual change that the information brings about. In plain language, knowledge is the accumulation of many small inputs of information, each one reshaping what came before.

What makes Brookes’ formulation powerful is the implication that knowledge is a structure built from bits of information, not a loose pile of facts. Information is the agent of change, and knowledge is the structured result of repeated changes over time. Brookes was deeply influenced by Shannon’s communication theory, and later scholars have explored how a Shannon-like logarithmic measure might be applied to make the equation quantitatively precise. While the equation is more conceptual than strictly measurable, it gives the field a memorable way to express the link between the two ideas at its core. It also echoes Belkin’s view that information matters because of the change it produces in a knower.

Machlup’s economic view: information as a resource 🔗

The thinkers above approached information from a cognitive or philosophical angle. Fritz Machlup, an Austrian-American economist at Princeton, looked at it through an entirely different lens. In his landmark 1962 study, The Production and Distribution of Knowledge in the United States, Machlup treated knowledge as a commodity that is produced, distributed, and consumed much like any other economic good.

Machlup set out to measure the size of what he called the knowledge industry. He examined everything connected with telling anyone anything, from education and research to publishing, advertising, and the manufacture of typewriters. His startling conclusion was that the knowledge industry already accounted for nearly 29 percent of the United States gross national product, and that a large share of the workforce was employed transmitting or receiving knowledge rather than producing physical goods. He identified several broad sectors of this economy, including education, research and development, the media of communication, information machines, and information services.

Machlup’s work is now seen as a foundation stone of information economics and of the wider study of the post-industrial information society. By showing that information and knowledge carry measurable economic value, he reframed them as strategic resources for nations and organisations. His ideas laid groundwork for later concepts of the knowledge economy that shape education and technology policy today. For a country investing heavily in digital services, software, and higher education, the relevance is obvious: information is not a by-product of the economy but increasingly its engine.

Bringing the four views together 🔗

These four perspectives are not rivals fighting for a single correct answer. They are complementary lenses. Belkin tells us information is defined by its effect on the user’s mind. Wersig and Neveling remind us that the word legitimately carries at least six different senses depending on context. Brookes captures the precise relationship between information and the knowledge it builds. Machlup zooms out to show information functioning as a measurable economic resource across society. Together they explain why information professionals must think about storage and structure, meaning and relevance, cognitive effect, and economic value all at once. A librarian organising a collection, a search engineer tuning relevance, and a policymaker funding digital infrastructure are each working with the same phenomenon viewed from a different angle.

Understanding these frameworks is more than an exam exercise. It shapes how systems are designed, how services are evaluated, and how the profession argues for its own value in a world where the volume of available information keeps multiplying. The thinker who can move comfortably between these viewpoints is far better equipped to tackle real problems than one who clings to a single definition.

What do you think? Which of these four approaches best matches the way you personally experience information when you sit down to study or search online? And as more of daily life shifts to digital platforms, do you believe Machlup’s economic view of information will become even more central to how we understand the field?

References

1. https://asistdl.onlinelibrary.wiley.com/doi/abs/10.1002/asi.4630270402
2. https://informationmatters.org/2023/10/whither-information-science-fireside-chat-with-nick-belkin-a-pioneer-of-the-cognitive-paradigm/
3. https://pages.gseis.ucla.edu/faculty/bates/articles/information.html
4. https://www.sciencedirect.com/science/article/abs/pii/S0306457399000308
5. https://www.igi-global.com/viewtitle.aspx?TitleId=97071
6. https://press.princeton.edu/books/paperback/9780691003566/the-production-and-distribution-of-knowledge-in-the-united-states
7. https://historyofinformation.com/detail.php?entryid=3295
8. https://en.wikipedia.org/wiki/Knowledge_industries