Is classification necessary after
Google?
Birger Hjørland
Royal School of Library and Information Science, Copenhagen, Denmark
Abstract
Purpose – The purpose of this paper is to examine challenges facing bibliographic classification at
both the practical and theoretical levels. At the practical level, libraries are increasingly dispensing
with classifying books. At the theoretical level, many researchers, managers, and users believe that the
activity of “classification” is not worth the effort, as search engines can be improved without the heavy
cost of providing metadata.
Design/methodology/approach – The basic issue in classification is seen as providing criteria for
deciding whether A should be classified as X. Such decisions are considered to be dependent on the
purpose and values inherent in the specific classification process. These decisions are not independent
of theories and values in the document being classified, but are dependent on an interpretation of the
discourses within those documents.
Findings – At the practical level, there is a need to provide high-quality control mechanisms. At the
theoretical level, there is a need to establish the basis of each decision, and to change the philosophy of
classification from being based on “standardisation” to being based on classifications tailored to
different domains and purposes. Evidence-based practice provides an example of the importance of
classifying documents according to research methods.
Originality/value – Solving both the practical (organisational) and the theoretical problems facing
classification is necessary if the field is to survive both as a practice and as an academic subject within
library and information science. This article presents strategies designed to tackle these challenges.
Keywords Classification, Epistemology, Library practice, Knowledge organisation
Paper type Research paper
Introduction
Classification (together with indexing, document description, and metadata
assignment) forms the basis of knowledge organization (KO)[1], both a practical
activity and a main sub-discipline of library and information science (LIS), which
focuses on improving this activity. Many consider KO to be the core of LIS, and KO has
been institutionalized with professors, journals, conferences, educational programs etc.
(cf. Pattuelli, 2010). The practice of classification and KO has been carried out in
libraries for more than 100 years. Formally speaking, it has also been an academic
subject in LIS programs since Melvil Dewey (1851-1931) established the first school of
“library economy” in the USA in 1876. The outlook for the future is, however,
fundamentally challenged by digital technologies at both the practical and at the
theoretical levels. In hindsight, the question arises as to whether KO has ever had a
sound theoretical basis because, as discussed below, questions such as: “How do we
decide whether A is a kind of B?” have not been properly addressed in the field of KO.
At the practical level, we are facing the following challenge: the two largest Danish
libraries, The Royal Library in Copenhagen and the State Library in Aarhus, have both
almost entirely ceased using their own classification systems as well as classifying
The current issue and full text archive of this journal is available at
www.emeraldinsight.com/0022-0418.htm
Is classification
necessary after
Google?
299
Received 17 May 2011
Revised 5 September 2011
Accepted 6 September 2011
Journal of Documentation
Vol. 68 No. 3, 2012
pp. 299-317
q Emerald Group Publishing Limited
0022-0418
DOI 10.1108/00220411211225557
their books themselves. The decision to do this may have been made based on the
following considerations:
.
Many libraries now rely mainly on the Dewey Decimal Classification (DDC)
made by the Library of Congress (LC)[2] and disseminated in the MARC
records[3] rather than making their own classification of each document.
.
Many library directors expect that, in the future, large scanning projects (such as
that which is being conducted by Google) may enable full text searches to be
carried out of all available content. For this reason, they may consider it a waste
of resources to classify or index books.
.
Many libraries, including The Royal Library in Copenhagen, now also rely on
user tagging and may perhaps expect that this will somehow act as a substitute
for professional indexing and classification.
.
Users mostly find the books they need using tools other than the library online
public access catalog (OPAC)[4].
This means that we must distinguish between libraries functioning as tools for finding
documents, as document-delivery services[5], and as reference (or other) services[6].
Both the finding function and the delivery function of libraries are seriously threatened
by the so-called “library bypass”, which is the result of publishers’ digital libraries as
well as possible tendencies towards open-access publishing. Here, however, we are
concerned with KO, and therefore we will only consider the KO carried out by libraries
and bibliographical databases from the perspective of the competing systems of KO
available to users.
Our strategy regarding how to develop KO should be based on the premise that
users today have access to the internet[7]. This means that every specific system or
classified collection is facing the challenges which arise from competing systems and
services. For a user who is interested in a specific issue, it does not matter whether or
not the classification/KO is made by a local library. As an aid to finding information,
the best[8] KO is only one click away (and there is no need for the second-best KO or for
the hundreds of lesser KO systems used in parallel by libraries, publishers, or
bibliographical databases). By implication, the theory and practice of classification and
KO should aim to provide high-quality services on a global scale, for example, in
subject-specific bibliographical databases, in WorldCat, and in related bibliographies
and catalogs.
Given the significant reliance on centralized classification and the challenges posed
by smart technologies, it follows that there is a need for control mechanisms to check
the quality of the classifications made, for example, by LC. There is far too little
research about the quality of indexing and classification today, and particular
decisions are not documented and made available for research. If the centralized
classifications are not of a very high quality, users may not find them to be viable,
given the many alternatives. In his study, Larson (1991) indicated that many users did
not find Library of Congress Subject Headings (LCSH) useful, and even found them to
be harmful in the online context. He wrote:
Experience in catalog use may not necessarily imply that users have been “conditioned” to
avoid subject searches [i.e. use of controlled vocabulary], although such conditioning appears
to be a likely result of gaining experience in catalog use, whether card or online catalog. We
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would suggest, as a hypothesis for further study, that individual users’ experiences of subject
search failure and information overload lead them to reduce their use of the subject index and
to increase their use of alternate means of subject access, such as title keyword searching and
shelf browsing following a known item search (Larson, 1991, p. 211).
A more recent study came to a similar conclusion:
These results point to a characteristic use in the University of Granada of a strong preference
for searching by title (49%), followed by searches by author (37%), and finally, by subject
search (14%). Our findings come to support the results of previous authors, highlighting the
inherent difficulties and reduced interest surrounding searches by subject [i.e. controlled
vocabulary] (Villen-Rueda et al., 2007, p. 336).
These two studies may or may not reveal the true picture (for a different conclusion,
see Gross and Taylor, 2005), and there is a desperate need for more studies. Another
indication of the crisis of bibliographic classification is that the citation databases from
Thomson Reuters only have a rough classification of the journals they index based on
an “intuitive” rather than any kind of scholarly methods (cf. Leydesdorff, 2006, p. 602).
That these very successful databases have not found it worth investing in the
classification of their articles is also an indication of a crisis of classification as
ordinarily understood. We shall not go further into the actual situation here; at this
point, I simply want to point to a possible problem which is concerned with the
principles and quality of subject analysis, to which we shall return below.
The challenge on the practical level can therefore be formulated this way: how can
LIS professionals contribute to the findability of documents, given the availability of
many competing services in the “information ecology”? The answer involves, among
other things, a strongly coordinated organization of efforts and a strengthening of the
connection between theory and practice in KO.
At the theoretical level, we are facing other challenges. We now have Google, for
example, which students use far more than they use library catalogs in order to find
what they need (De Rosa et al., 2005, 2006; Pors, 2005). This triggers the question: can
information retrieval (IR) theoretically be carried out perfectly without any kind of
“classification”? The well-known computer scientist and information scientist Karen
Sparck Jones (2005) argued that techniques such as “relevance feedback” would
remove the need for classification as it is commonly understood. In previous years, the
famous computer scientist and information scientist, Gerard Salton, has also argued:
Acting as if we were stuck in the nineteenth century with controlled vocabularies, thesaurus
control, and all the attendant miseries, will surely not contribute to a proper understanding
and appreciation of the modern information science field (Salton, 1996, p. 333).
Is classification – even at the theoretical level – still needed in the post-Google era? Or
are computer algorithms able to do a 100% satisfactory job without the need for
classification[9]?
This theoretical challenge constitutes a serious threat to the justification of
classification, KO, and LIS as fields of both research and practice (cf. Bawden, 2007). If
we believe that we in the field of knowledge organization are entitled to a place in the
academic world as well as in the practice of KO, we have to be able to provide both
academic and practical justification for classification and in other forms of KO. This
article is an attempt to contribute to the development of such an argument.
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Digression: some comments about the UDC
The UDC system is a classification system that was proudly developed by the
documentation movement (which I consider to be a part of LIS). First of all, it reflected
a high level of subject knowledge and corresponded well to the academic discourses in
various fields. Second, it was originally designed not just for monographs, but also for
articles and other kinds of documents. It was therefore much more detailed than, for
instance, DDC. I say “was proudly developed” because, although it still exists and some
people still contribute to its development, I do not think that we can take pride in it any
longer (although I have great respect for the small group of researchers who are still
working on it, such as Ian McIlwaine; see, for example, McIlwaine, 2010). There are
various reasons for this decline. In a previous study (Hjørland, 2007a), I argued that our
community has not been able to maintain and update this system properly, and I find it
almost scandalous that the new edition has so many totally obsolete sections.
The UDC was once maintained by the International Federation for Information and
Documentation (FID), which, after a period of crisis, was dissolved in 2002. Before that
time, there were many committees (international as well as national, including a
Danish committee) working together for the improvement of this system. Today, to my
knowledge, nothing similar exists, and there are no large-scale groups, committees, or
organizations working together to produce high-level classifications (or thesauri,
ontologies, or related tools)[10]. I believe that this is becoming a problem in the digital
environment because the development of quality classification systems or KO tools is
much too big a job for a single library or for small groups of experts such as those who
are maintaining the DDC in LC. If our community is to be able to produce something
which would be able to make LIS more visible and improve access to information in the
post-Google Era, this would probably need to be based on large-scale international
cooperation involving LIS practitioners, LIS researchers, and (other kinds of)
specialists, including subject specialists in all major fields. The practical work of
maintaining and updating a given system (such as the UDC) is not, however, research
in itself, but should be based on research. What could be recognized as research would
be the publication of articles which carefully argue for the specific decisions made,
considering empirical, logical, historical and pragmatic issues (e.g. why A should be
considered as part of B in a specific context).
The UDC – as well as other traditional library classification systems – is also
designed in such a way that makes it suitable for arranging books on shelves[11]. This
implies constraints that are unnecessary in online searches, and as such the problems
of shelving and retrieval functions should be considered separately. This may also
form part of the explanation of why the UDC is no longer playing its former role.
It should also be said that systems such as the UDC may, in the past, have been
based on the idea that classifications are neutral, objective, and content-independent
decisions (e.g. that concept A is related to concept B in specific ways, regardless of
domain or perspective). I believe that these assumptions are wrong and should be
replaced by principles that are more in accordance with alternative views. This would,
in my opinion, imply the need for specific KO tools aimed at different subjects and
paradigms. The widespread philosophy that classification can be standardized and
thus reused in different contexts seems problematic because different discourse
communities develop their own terminology, meanings, and relevance criteria. Strong
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arguments can therefore be put forward in accordance with the view that classification
should be tailored towards different domains, epistemic communities, and user groups.
The task at hand is therefore not just to update systems such as the UDC or to create
a set of thesauri spanning all disciplines or other kinds of knowledge organizing
systems (KOS; of which the most advanced[12] are ontologies; cf., Hodge, 2000).
Instead, the task is to provide an overall framework for developing and discussing
different alternatives for ways in which users will be enabled to make informed
decisions during IR, along with a broad-based development of specific tools. However,
large international projects aimed at classifying the world’s knowledge based on
literary warrant (i.e. through an examination of concepts in the literature) still seem to
be important and are probably necessary for the survival of KO. The main difference
between the former understanding of the UDC and an approach based on today’s
outlook would be that the new approach should be less prescriptive. Instead, it should
be more descriptive and contextual (and based on, among other things, bibliometric
studies, historical dictionaries, and other forms of domain analysis).
What is classification?
We could say that classification is the interdependent processes of:
.
defining classes;
.
determining relationships between classes (such as hierarchical relations, among
others), i.e. making a classification system; and
.
assigning elements (in LIS, documents) to a class in a given classification system.
This is equivalent to the interdependent processes of:
. defining concepts (see Hjørland, 2009);
.
determining semantic relations between concepts (see Hjørland, 2007b); and
.
determining which elements fall under a given concept (to assign a given “thing”
to a concept).
Example
To say that the concept of “the Mu¨ller-Lyer illusion” is a kind of “optical illusion”,
which is a kind of “perceptual phenomenon”, which is a kind of “psychological
phenomenon”, is the same as classifying “the Mu¨ller-Lyer illusion” within a class
termed “optical illusions”, which is part of the broader class of “perceptual
phenomena”, which is part of the broader class of “psychological phenomena”.
A recent dissertation wrote:
Ingetraut Dahlberg, another influential classificationist, states that “the elements” of
classification schemes are “concepts or representations of concepts” (Dahlberg, 1978, p. 9).
One could thereby conclude that when a concept is chosen for a class, the concept in question
refers to something which should be shared by all documents of that class, and that this
concept is treated by the documents. However, taking the label “011” in the DDC as an
example, it refers to a class of documents that has the common feature that they are
bibliographies and not about bibliographies (Gunnarsson, 2011, p. 16).
What Gunnarsson illustrates here is that there is an important difference in whether a
thing or a document (A) is a kind of X or is about X. His quote shows that the criteria
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for assigning A to X depend on whether we are speaking of form classes or subject
classes, although both kinds of classes are defined by a concept (e.g. “bibliography”).
He does not, however, discuss the criteria used to decide whether or not A should be
assigned to X (which corresponds to define the meaning of a concept, for example
“bibliography”).
In the context of librarianship, “classification” is often used for systems such as the
DDC, the UDC, the LCC, Colon, or Bliss, and its process involves assigning individual
books or other documents to one or more classes within such a system, as opposed to
verbal indexing systems (see Figure 1).
The fundamental distinction in Figure 1 is between classification systems and
verbal indexing systems, which I consider to be “traditional” in KO, but which has
been criticized by Lancaster (2003, pp. 20-2), who argued that one should not speak of
assigning classification codes as “classification” in opposition to the assignment of
indexing terms as “indexing”. “These terminological distinctions”, he writes, “are quite
meaningless and only serve to cause confusion” (Lancaster, 2003, p. 21). The view that
this distinction is purely superficial is also supported by the fact that a classification
system may be transformed into a thesaurus and vice versa (cf. Aitchison, 1986, 2004;
Broughton, 2008; Riesthuis and Bliedung, 1991).
Mikael Gunnarsson further writes:
Indexing in particular, but classification as well, stresses the assignment of labels to
documents rather than the assignment of documents to classes of documents” Gunnarsson
(2011, p. 85; emphasis in original).
However, I would dispute this distinction because the act of labeling a document (say
by assigning a term from a controlled vocabulary to a document) is at the same time to
assign that document to the class of documents indexed by that term (all documents
indexed or classified as X belong to the same class of documents).
It is therefore important to realize that all of the different kinds of systems in
Figure 1 (with the possible exception of free text systems) are different kinds of
“classification systems”. The most important difference between the different indexing
languages shown in Figure 1 is between “free text systems” and the others (Figure 2).
Figure 1.
The traditional view of the
different kinds of indexing
languages
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In free text systems, none of the classification is carried out by personnel associated with
the bibliographical system, as there are only possible “classifications” made by the
authors of the documents. These are represented in the free text systems in the form of
relations between meanings in a given text (for example, when it is said that A is a kind
of B), which are developed in the discourse communities to which a given text belongs.
In all other kinds of systems, there are classifications made by LIS personnel (or
others responsible for developing, maintaining, and using the systems as “metadata” in
bibliographical systems). All such systems may be termed “controlled vocabularies,”
and they are “normative” and “prescriptive”. They may also be termed “bibliographic
classifications” (classification of documents about, for example, plants, animals,
chemicals, religions, languages, genres, and sports). As such, they are opposed to
“scientific and scholarly classifications” (e.g. classifications of plants, animals,
chemicals, religions, languages, genres, and sports) developed in different disciplines
and reflected in the documents being indexed. Bibliographical classification is not
independent of scientific classification; rather it must, to a large extent, be based on and
reflect scientific/scholarly classifications. Therefore, LIS cannot develop adequate
theories of classification if problems of scientific classification are ignored.
A more recent overview of knowledge organization systems have been presented by
Hodge (2000), who grouped them into three general categories:
(1) term lists, which emphasize lists of terms, often with definitions;
(2) classifications and categories, which emphasize the creation of subject sets; and
(3) relationship lists, which emphasize the connections between terms and
concepts.
What Hodge has actually provided, though recognizing that this list is not
comprehensive, is a suggestion for a taxonomy of KOS:
Term lists
.
Authority files
.
Glossaries
.
Dictionaries
.
Gazetteers
Classifications and categories
.
Subject headings
. Classification schemes
.
Taxonomies
Figure 2.
The two basic kinds of
indexing
languages/information
languages
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Categorization schemes
.
Relationship lists
.
Thesauri
. Semantic networks
.
Ontologies
In this paper, we shall not consider each kind of KOS or analyze Hodge’s taxonomy.
The most important difference between the different kinds of KOS seems to be the
different kinds of semantic relations being displayed. In traditional classification
systems, hierarchical relations and the relationship between synonyms and homonyms
are the most important. In ontologies, a large range of semantic relations are possible; it
is a question of whether other kinds of KOS are needed for KO theory or whether other
kinds of KOS should be considered special cases of ontologies with more limited ranges
of semantic relations. Dagobert Soergel wrote:
Unification: Ontologies
The relationships between document components in a document model, the tags in a
document template or a metadata schema, the table structure in a relational database (or the
object structures in an object-oriented database), and the relationships between concepts can
all be traced back to (or defined in terms of) an entity-relationship model [. . .] Such a model is
an ontology, so all structures in a digital library can (and should) be conceived as subsets of
an overarching ontology (Soergel, 2009, p. 38).
Or, in the words of Lars Merius Garshol:
With ontologies the creator of the subject description language is allowed to define the
language at will [. . .] [A s]ummary of the relationship between topic maps and traditional
classification schemes might be that topic maps [i.e. ontologies[13]] are not so much an
extension of the traditional schemes as on a higher level. That is, thesauri extend taxonomies,
by adding more built-in relationships and properties. Topic maps do not add to a fixed
vocabulary, but provide a more flexible model with an open vocabulary.
A consequence of this is that topic maps can actually represent taxonomies, thesauri,
faceted classification, synonym rings, and authority files, simply by using the fixed
vocabularies of these classifications as a topic map vocabulary (Garshol, 2004).
Both Hodge’s taxonomy of KOS and the taxonomy of indexing languages in Figure 1
emphasize form rather than content. It has already been said that, for example,
classifications may be converted into thesauri. This is an indication that the form or
formal aspects of KOS and indexing languages are less important. The central issue in
classification is, as previously stated, the way in which the semantic relations between
concepts are determined (e.g. how we decide whether or not A is a kind of B).
It should also be noted that a given KOS is much more than its systemic features.
When, for example, a classification system has been applied for years in a given library
many qualified decisions may have been made about what to classify as X. In this way
the system may then represent an important accumulation of knowledge, which is
seldom reflected in the scientific literature concerning KO (but may exist in the form of
minutes from meetings and as “tacit knowledge” among the indexers).
The Cranfield experiments, which were founded in the 1950s, introduced the famous
measures of “recall” and “precision” as evaluation criteria for system efficiency. They
found that classification systems such as the UDC and facet-analytic systems were less
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efficient compared to free text searches or low-level indexing systems (“UNITERM”).
According to Ellis (1996, pp. 3-6), the Cranfield I test revealed the following results:
.
UNITERM: 82.0 percent recall;
.
alphabetical subject headings: 81.5 percent recall;
.
UDC: 75.6 percent recall; and
.
facet classification scheme: 73.8 percent recall.
Although these results have been criticized and questioned, the IR tradition became
much more influential whilst library classification research relatively lost its influence.
Since then, a split has appeared between IR researchers (who tend to assume that
controlled vocabularies are not important) and KO researchers (who continue to
assume they are still important).
With regard to the construction of controlled vocabularies, Maniez (1997) found that
“compatibility is the paradise lost of information scientists, the dream of a universal
communication between information languages [indexing languages]. Paradoxically,
the information languages increase the difficulties of cooperation between the different
information databases”. Maniez’s insight is an argument against the need for
classification as it is traditionally performed; it seems to suggest that each controlled
system tends to make its own arbitrary decisions (rather than reflecting an underlying
order), and thereby tends to make a federated search or integrated search less efficient.
To sum up, to classify is to define the “kind” which a given “thing” is, and how that
kind is related to other kinds. This is a fundamental process that all human beings
carry out many times each day (e.g. when sorting which things are “food” and which
are not, which fruit is fresh and which is rotten, which desserts a child likes and which
s/he dislikes, etc.). All the different kinds of “indexing languages” and KOS are based
on the same sort of fundamental decisions.
Criteria for classifying
The underlying theoretical questions are: “How do we decide the criteria for assigning
document A to class X?” and the related question: “what are the criteria by which decisions
such as assigning the semantic relation X between the concepts A and B can be made?”.
Concerning the first problem (how do we decide whether we should classify
document A as belonging to class X) there are different principles in play. In the
mainstream library tradition, it has been a rule that at least 20 percent of a book should
be about X in order for it to be assigned to that class; in automatic indexing, on the
other hand, it is the occurrences of specific terms in A that determines whether or not it
is assigned to X. In request-oriented indexing it is the anticipated request from users
that determines when to assign A to X (the indexer asks himself: “Under which
descriptors should this entity be found?” and “Think of all the possible queries and
decide for which ones the entity at hand is relevant” (Soergel, 1985, p. 230). Finally, two
views in accordance with request-oriented indexing have been formulated by Rowley
and Farrow and by Hjørland, respectively. The core of indexing as stated by Rowley
and Farrow is to evaluate a paper’s contribution to knowledge and index it accordingly
(Rowley and Farrow, 2000, p. 99). In order to achieve good consistent indexing, the
indexer must have a thorough appreciation of the structure of the subject and the
nature of the contribution that the document is making to the advancement of
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knowledge. Or, as in the words of Hjørland (1992, 1997): “the subjects of a document are
its informative potentials”. While mainstream classification research is still based on
the objectivist understanding (a document has a subject), the minority view (that
document A is assigned subject X by somebody in order to support some specific
activities) is gaining a footing. I believe this last view is decisive for making a future for
classification in both theory and practice.
Concerning the second question (how to assign semantic relations between
concepts, for example how to decide that A is a kind of B) LIS personnel classifying or
assign terms from different kinds of controlled vocabularies may often assume that
such decisions are based on logic or on fixed semantic relationships between concepts.
Svenonius (2000, p. 131), for example, found hierarchical relations to be “wholly
paradigmatic or a priori [sic ]”. However, in my opinion, this is not a fruitful
perspective. As the following quotation expresses, a controlled vocabulary should be
understood as an interpretation:
A controlled vocabulary is a way to insert an interpretive layer of semantics between the term
entered by the user and the underlying database to better represent the original intention of
the terms of the user (Fast et al., 2002).
Such an interpretation is often an empirical question, and often different perspectives
and interest have different criteria for deciding semantic relations. In chemistry, for
example, helium is considered a noble gas; however, in Stowe’s Periodic Table (based on
quantum mechanics) helium appears with the alkaline earth metals (cf. Channon, 2011).
In contemporary science the place of helium has not been solved, and it is an open
question whether or not there is one correct answer (cf. Scerri, 2007). Such considerations
make it important not just to consider classification to be about logical decisions, but to
be based on interpretations of discourses and on the negotiation of different interests.
Although researchers such as Andersen (2004), Cornelius (1996), Feinberg (2008),
Frohman (1983, 1990), Mai (2000, 2011), Olson (2001, 2002) and Ørom (2003) have
promoted interpretative views of classification and have formed part of an important
“social turn” in classification research, this view is still not very influential and has not
resulted in the formation of a coherent theoretical approach. There are, for example, no
textbooks on indexing and classification written from such a social and interpretative
perspective in which it is explained how the relation X between concepts A and B
should be determined and assigned. Theoretically speaking, the quotation from Fast
et al. (2002) raises an important question regarding the basis on which LIS personnel
construe and apply this “interpretative layer”.
Olson (2001) examined the way in which LCSH were used to index some books in
the field of gender studies, and found the indexing to be problematic. For example, the
concept of “voice” (in relation to the views of a minority) is not represented in LCSH.
According to Olson’s interpretation, this may be due to poor indexing of marginalized
topics (as opposed to mainstream topics). My interpretation is unfortunately more
pessimistic: I believe that this poor indexing is due to a lack of subject knowledge. The
terms and relations in LCSH in relation to this field (gender studies) seem to be
speculative and far away from the points of view that the literature in the field tries to
put forward. This probably does not only apply to the views of minorities, which seem
to be poorly represented by LC, but constitutes a general tendency that will also affect
majority views. I agree with Olson that it is problematic that LC fails to see that the
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books examined by Olson are about “voice” (this is particularly so because, in my view,
one of the most important functions of libraries – and of KO – is to help different
“voices” be heard). However, I have no statistical basis for claiming that LC indexing is
of a poor quality; I simply wish to state that this is an important issue for investigation
and that we need more qualitative, interpretative studies like Olson’s in order to better
understand and improve indexing and retrieval.
More generally, what principles form the basis for the concepts classified in a given
KOS? I consider subject headings, classification codes, etc. to be, in principle, the
equivalent of chapter titles and section headings in a book about the history of the
domain to be classified. Consider, for example, histories of Danish fiction. During the
twentieth century, several important histories of Danish fiction were written, first from
more traditional viewpoints, and then some reflecting particular views such as
feminism, Marxism, postmodernism, etc. Each work reflects the subjectivity of both its
author and its time (Zeitgeist). In spite of this subjectivity, such histories also reflect
different levels of quality (they are reviewed and evaluated, and some are considered to
be brilliant while others are considered to be bad). There is no way to avoid such
subjectivism, and it would probably be a bad idea to try to do so. A given history may
attach new labels to a given set of books, for example “magic realism”. Such labels are
not necessarily derived from the literature, but are often assigned to it on the basis of a
new conceptualization or interpretation. In the same way, libraries and the LC should
assign labels such as “voice” to certain books in order to support important goals
associated with the discourses of which the books are a part. By implication, it is
important for LIS to study how concepts of genre and other methods of conceptualizing
documents are used, and for researchers to incorporate them into their own
conceptualizations[14]. This may seem extremely costly; however it should be
considered that this kind of knowledge is not only necessary in relation to indexing,
but in relation to any kind of qualified work concerning information. Furthermore, this
kind of knowledge is assumed in high standard libraries and bibliographical databases
such as the National Library of Medicine and the MEDLINE database. Lowering the
cost of employing qualified staff may ultimately mean that KO and classification will
disappear because there will be no need for classifications other than the best[15] ones.
In the past, it has often been assumed that to say of what kind a given “thing” is and
how that kind is related to other kinds is a task which has one true solution, i.e. that
things have an “essence” and that classification reflects these “essential” properties.
Plato and Aristotle, for example, are generally considered to be essentialists. The idea
of essentialism is related to the concept of natural kinds and may also be expressed by
Plato’s metaphor of “carving nature at its joints”. Essentialism has come under fierce
criticism, however, as stated by Rachel Cooper:
In recent years, traditional essentialist accounts of natural kinds have come in for fierce
criticism. A major difficulty is that for biological species, which are traditionally considered
amongst the best examples of natural kinds, no plausible candidates for the essences can be
found. Several different criteria may be employed by biologists seeking to determine species:
morphological futures, evolutionary lineages, the criteria of reproductive isolation, or genetic
features. On examination none of these appears suitable candidates for being the essential
properties of biological species (Cooper, 2005, p. 47).
This critique claims that classifications are made in order to facilitate certain human
tasks, and that the properties chosen for classification depend on the purpose of the
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classification, as different purposes require different classifications, and that
classifications are theory-dependent (or indeed that a classification is a theory of
sorts). In a paper published in Knowledge Organization (Hjørland, 2011b), I suggested
that the ideal form of the periodic system of chemistry and physics depends on whether
quantum mechanics (QM) or more traditional chemical views are emphasized[16]. The
question of essentialism may, however, still be considered to be an open question.
To conclude this section, classification involves considering and negotiating
different theories and interests within the domain that is being classified[17].
How is library classification related to other forms of classification?
In Hjørland (2008), I provided the following model for “the traditional view of
classification” in KO (see Figure 3).
This view may be expressed by stating that there is only one way in which nature has
joints, or as Stamos wrote: “Nature itself has supplied the causal monistic essentialism.
Scientists in their turn have simply discovered and followed (where ‘simply’ – ‘easily’Þ”
(Stamos, 2004, pp. 138-9). Library and information scientists, in turn, must study scientific
classifications and “simply discover and follow” scientific classifications (where again
“simply” – “easily”). When LIS professionals classify a given book, the concepts which
they use are derived from the literature, and are not primarily constructed by LIS
professionals. As Hulme (1911, pp. 46-7) has stated: “The real classifier of literature is the
book-wright, the so-called book classifier is merely the recorder”. This view, however,
almost disappeared in KO in the second half of the twentieth century (to be ousted by, for
example, facet-analytic and user-oriented perspectives)[18].
In opposition to this traditional view it may be suggested that classifications reflect the
purposes for which they are designed and that different sciences, theories, and human
activities classify the world (more or less) differently[19]. Both the practice of science and
the practice of information science can therefore be seen as more constructive. The
periodic system of physics and chemistry seems to be the ultimate challenge to this view.
For LIS and KO, the implication is that, in both cases, classification is not
constructed within our field but is dependent on subject knowledge produced outside
LIS. The pragmatic view emphasizes that LIS/KO should consider the purpose of its
classification and the activities that classification is made to support.
Why classification is needed: the case of evidence-based practice
If classifications are to be relevant, they must consider and negotiate between different
views and interests. In order to support these given views, classifications must enable
Figure 3.
Model for the traditional
view of classification in KO
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IR according to the relevance criteria associated with them. To classify should be to
make relevant distinctions in relation to the goals of the system, and therefore implies a
consideration and negotiation of different views and interests. Google and other similar
IR systems are certainly impressive, but how do they classify and prioritize the
relevant information? We tend to think of such systems as neutral and objective tools,
but they cannot be. Any system is always biased in some way or another (see, for
example, Fortunato et al., 2005; Gerhart, 2004; Introna and Nissenbaum, 2000). Search
engines may be calibrated in order to provide different findings or rankings. In order to
make such a calibration (or simply to evaluate the systems), we need to have some kind
of classification of what should be found. Thus far, in the field of LIS, we have mainly
used assessments of relevance based on “user relevance” (see Hjørland, 2010).
However, if we are to trust, for instance, retrieved medical documents, it would be
better to base our relevance judgments on scientific criteria (such as research methods),
rather than on the opinions of users. This is done most explicitly in the
interdisciplinary movement known as evidence-based practice (EBP), which
developed from evidence-based medicine. In this movement, documents are
classified according to very explicit criteria (based on a hierarchy of research
methods[20], i.e. criteria for what counts as evidence). EBP is presented and discussed
in Hjørland (2011a), in which it is concluded that the focus on scientific argumentation
in EBP constitutes an important and long overdue contribution from EBP to LIS.
However, parts of the underlying epistemological assumptions should be replaced:
EBP is too narrow, too formalist, and too mechanical an approach on which to base
scientific and scholarly documentation. Whether or not we accept the philosophy of
EBP wholeheartedly, or whether we accept the epistemological criticism raised against
it, classification appears to be a necessary activity. If a given hierarchy of research
methods is accepted as generally the best, papers need to be classified according to the
research methods listed in this hierarchy. If such a hierarchy is formed, it might be
possible to construe algorithms that – to some degree of certainty – can classify the
documents automatically (although the classification itself has to be constructed
beforehand, leading to so-called “supervised machine learning” or “supervised
classification”). If the critique put forward by me (Hjørland, 2011a) is accepted, this
means that the classification of research methods is less formalist and mechanical and
that classification therefore becomes more interpretative and presupposes more
contextual knowledge. The point to note is that medical researchers, for example,
cannot rely on IR systems that are not based on metadata and do not reflect the
scientific criteria in a given domain. I am not arguing that EBP is the final answer, but I
believe that it is a much healthier approach on which to base systems of IR and
classification than the paradigms which have dominated LIS and KO for the last 30
years. For the moment, suffice it to say that EBP offers a rationale from which we can
reach the important conclusion: we cannot manage without classification.
Conclusion: why classification is necessary after Google
We have now considered how classification is challenged in library practice as well as
in information retrieval theory. We have considered different forms of classification
including those done by search engines or algorithms. We have pointed out that at the
core is classification theory regarding whether A should be considered a kind of X and
how concepts are related. All kinds of knowledge organization systems may be seen as
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kinds of ontologies, which consist of selections of concepts and their selected semantic
relations from a specific conceptualization. Ontologies are not just neutral reflections of
an objective reality, but are constructed from a world-view that is fruitful for some
purposes and values, though at the expense of others. In developing this issue we saw
that such decisions involve consideration of subject-specific theories as well as
metatheories and “paradigms”. All this is a major challenge to traditional theories of
classification in our field. I believe my stated principles are necessary, but will
encourage information specialists to challenge them so that some consensus may
develop and we can work together for the future of KO.
Given this new theoretical understanding of classification and KO we can understand
why classification is necessary in any kind of library, documentation, or information
work: the criteria of classification are simply identical to criteria of relevant information
provision. It is my claim that an information specialist dealing with questions in Arts
would be better situated to do so if he or she has read and understood Ørom (2003) about
major paradigms in that domain and how they have affected library classification
systems. We should work in this direction for all domains.
Notes
1. There is a tendency to change the term from knowledge organization to information
organization (IO) or information architecture (IA). The term IO is now used, for example, at
the School of Information Studies at the University of Wisconsin-Milwaukee. In this article,
the more traditional term “KO” is used.
2. The DDC is published by OCLC Online Computer Library Center, Inc. It is developed and
maintained in the Library of Congress, but most of the editorial staff are employed by OCLC:
“The Dewey editorial office is located in the Decimal Classification Division of the Library of
Congress, where classification specialists annually assign over 110,000 DDC numbers to
records for works cataloged by the Library. Having the editorial office within the Decimal
Classification Division enables the editors to detect trends in the literature that must be
incorporated into the Classification” (cited from the Dewey Editorial Office; see http://staff.
oclc.org/,dewey/dewey.htm).
3. According to the website of the Royal Library: “At present most of the books in English will
be classified in the DDC code, whereas books in Danish are classified in the DK5” (see www.
kb.dk/en/kub/fag/hum/tors/kulturstudier/boeger.html).
4. For my own part, for example, I often find the books that I need for my research in reference
lists, at Amazon.com or the Web of Science, or in other places (and some of the books that I
find in these ways I subsequently borrow from my local library). I also find more relevant
books displayed as “new books” at the library of RSLIS, compared to what I find in the
classified catalogue.
5. One example of a combined function is the role of classification systems as browsing
systems on open shelves with physical books and materials. This function, however, will in
future be dependent on the display of physical documents rather than electronic documents
and is therefore also threatened by digital media. It is more likely that the future will bring
an increase in special exhibitions and that browsing whole libraries will be possible
electronically in the form of “virtual libraries”, which can be displayed by multidimensional
organizations.
6. It is important to realize that the kind of knowledge which is needed in order to classify
knowledge is equally relevant when providing guidance to users, searching for information,
and other related tasks. Shachaf (2009) indicates that the Wikipedia reference desk, which
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relies on volunteers, is as good as a library staffed by professionals. This is a provocative
suggestion that needs to be considered carefully. My suggestion is that the kind of
knowledge that is needed for answering questions overlaps a great deal with the kind of
knowledge that is needed in order to classify documents.
7. There may be a need for services to help users without access to the internet. Such services
cannot, in my opinion, justify the maintenance of a research field such as KO.
8. The “best” KO means the best for a given task. Although it is argued in the article that no
system is the best for all purposes, a system may be the best one in a specific search
situation.
9. This question may be reformulated as: what are the relative contributions that different
kinds of subject-access contribute to successful retrieval? (cf. Hjørland and Kyllesbech
Nielsen, 2001).
10. Large-scale international development of broad ontologies might take place in some subject
fields (e.g. GeneOntology), but in that case this seems not to be something that the
community of KO is engaged in and which contributes to make our field visible.
11. The UDC was originally designed for a universal bibliography at the International Office of
Bibliography, created in 1895 in Belgium and based on a card catalog system. It was
therefore not designed for shelving purposes, but it has mostly been used in large research
libraries in which it has also served the needs of shelving.
12. Most advanced in the sense of allowing many kinds of semantic relations to be expressed.
13. A topic map is a standard for representing knowledge based on an ontology.
14. See Abrahamsen (2003) for an example of how a genre label originated in popular music.
15. ”Best ones” means best for needed tasks. Although no KO is optimal for all purposes it
cannot be inferred that any system is optimal for some purposes: Many systems may in
reality be considered superfluous.
16. Timothy Stowe’s periodic table for physicists from 1988 may best represent QM, while other
versions may better reflect other points of view. Scerri (2007, p. 286) suggests “the left-step
table” as the best solution, but writes: “I am well aware of the resistance that this proposal
will meet, especially from the chemical community”. This suggests that different theories
and interests are at play even in this, the hardest of the natural sciences. However, of course,
one theory at any given point in time may be able to combine different views and thus
appear to be the only theory, and by implication, provide one true classification of the
elements – at least for a period of time.
17. The anthropologist Jan Ovesen, during his term of office at the Royal School of Library and
Information Science in Copenhagen, criticized the way in which anthropology was classified
according to the Danish Decimal Classification: “In the academic world, both in Denmark
and internationally, cultural and social anthropology (in Denmark still termed by its
previous name, i.e. ethnography) is an independent science with its own institutes at
universities, its own terminology and scientific historical development, and a relatively well
delimited subject literature. [Note omitted] This is, however, not the case in DK5! [The
Danish Decimal Classification System, 5th ed., which is a Danish modification of the Dewey
system]. In this system it is more important, apparently, to draw meaningless distinctions
between, for example, European and non-European cultures, between ‘developed cultures’
and ‘primitive people’, between the life of ordinary people and cultural processes, between
social anthropology and ethnography etc. These distinctions obviously come from the
strange understanding that ethnography should only deal with the pure description of
primitive people, which are not in a process of cultural change caused by the meeting with the
Western world. From the point of view of the discipline such delimitation is totally absurd.
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Firstly, there is today general consensus that ‘pure descriptions’ do not exist in ethnography
or in other humanistic disciplines. Descriptions are not independent of the cultural
background, the education, the personality etc. of the ethnographer. All description involves
at the same time one or another kind of interpretation or even analysis. Secondly, decades of
discussion about the concept of primitive have resulted in the view that it seems no longer
meaningful to use the phrase ‘primitive people’. Thirdly, today few if any groups of people
exist who are not culturally changed in one way or another caused by contact with Western
industrialized societies. One thus faces the paradoxical situation that the discipline of
anthropology, which over the decades has experienced an important growth and
development, in DK5 is represented by a class (59.5) in which the increase of literature
must by necessity be very limited. The result has been that the central works of
anthropology are not kept together, but are scattered in a number of rather different classes.
Besides class 59.5 the classes 29, 30.12, 39 and 98 are the most important ones” (Ovesen,
1989, pp. 120-2; translated by BH, emphasis in original).
18. My own position is therefore closer to this traditional view than, for example, the
facet-analytic, user-oriented or cognitive views.
19. A main spokesman of this view is Dupre´ (e.g. 1993).
20. “I a Evidence from a meta-analysis of RCTs [randomized controlled trials]; I b Evidence from
at least one RCT; II a Evidence from at least one controlled study without randomisation; II b
Evidence from at least one other type of quasi-experimental study; III Evidence from
non-experimental descriptive studies, such as comparative studies, correlation studies and
case-control studies; IV Evidence from expert committee reports, or opinions and/or clinical
experience of respected authorities” (Geddes and Harrison, 1997).
References
Abrahamsen, K.T. (2003), “Indexing of musical genres. An epistemological perspective”,
Knowledge Organization, Vol. 30 Nos 3/4, pp. 144-69.
Aitchison, J. (1986), “A classification as a source for thesaurus: the bibliographic classification of
H.E. Bliss as a source of thesaurus terms and structure”, Journal of Documentation, Vol. 42
No. 3, pp. 160-81.
Aitchison, J. (2004), “Thesauri from BC2: problems and possibilities revealed in an experimental
thesaurus derived from the Bliss music schedule”, Bliss Classification Bulletin, Vol. 46,
pp. 20-6.
Andersen, J. (2004), “Analyzing the role of knowledge organization in scholarly communication:
an inquiry into the intellectual foundation of knowledge organization”, PhD dissertation,
Department of Information Studies, Royal School of Library and Information Science,
Copenhagen, available at: http://biblis.db.dk/Archimages/78.PDF (accessed July 20, 2010).
Bawden, D. (2007), “Editorial: The doomsday of documentation?”, Journal of Documentation,
Vol. 63 No. 2, pp. 173-4.
Broughton, V. (2008), “A faceted classification as the basis of a faceted terminology: conversion
of a classified structure to thesaurus format in the Bliss bibliographic classification,
2nd edition”, Axiomathes, Vol. 18 No. 2, pp. 193-210.
Channon, M. (2011), “The Stowe table as the definitive periodic system”, Knowledge
Organization, Vol. 38 No. 4, pp. 321-7.
Cooper, R. (2005), Classifying Madness: A Philosophical Examination of the Diagnostic and
Statistical Manual of Mental Disorders, Springer, Berlin.
Cornelius, I.V. (1996), Meaning and Method in Information Studies, Ablex, Norwood, NJ.
JDOC
68,3
314
Dahlberg, I. (1978), Ontical Structures and Universal Classification, Sarada Ranganathan
Endowment for Library Science, Bangalore.
De Rosa, C., Cantrell, J., Hawk, J. and Wilson, A. (2006), “College students’ perceptions of libraries
and information resources. A report to the OCLC membership. A companion piece to
‘Perceptions of libraries and information resources’”, OCLC Online Computer Library
Center, Dublin, OH, available at: www.oclc.org/reports/pdfs/studentperceptions.pdf
(accessed October 10, 2009).
De Rosa, C., Cantrell, J., Cellentani, D., Hawk, J., Jenkins, L. and Wilson, A. (2005), “Perceptions of
libraries and information resources. A report to the OCLC Membership”, OCLC Online
Computer Library Center, Dublin, OH, available at: www.oclc.org/reports/pdfs/Percept_
all.pdf (accessed October 10, 2009).
Dupre´, J. (1993), The Disorder of Things: Metaphysical Foundations for the Disunity of Science,
Harvard University Press, Cambridge, MA.
Ellis, D. (1996), Progress and Problems in Information Retrieval, Library Association Publishing,
London.
Fast, K., Leise, F. and Steckel, M. (2002), “What is a controlled vocabulary?”, available at: http://
web.archive.org/web/20030811115443/http://www.boxesandarrows.com/archives/what_
is_a_controlled_vocabulary.php (accessed December 7, 2010).
Feinberg, M. (2008), “Hidden bias to responsible bias: an approach to information systems based
on Haraway’s situated knowledges”, Information Research: An International Electronic
Journal, Vol. 13 No. 2, article 07, available at: http://informationr.net/ir/12-4/colis/colis07.
html (accessed March 24, 2011).
Fortunato, S., Flammini, A., Menczer, F. and Vespignani, A. (2005), “The egalitarian effect of
search engines”, arXiv:cs.CY/0511005 v1, available at: http://arxiv.org/abs/cs/0511005
(accessed July 20, 2010).
Frohmann, B. (1983), “An investigation of the semantic bases of some theoretical principles of
classification proposed by Austin and the CRG”, Cataloging & Classification Quarterly,
Vol. 4 No. 1, pp. 11-27.
Frohmann, B. (1990), “Rules of indexing: a critique of mentalism in information retrieval theory”,
Journal of Documentation, Vol. 46 No. 2, pp. 81-101.
Garshol, L.M. (2004), “Metadata? Thesauri? Taxonomies? Topic maps! Making sense of it all”,
Journal of Information Science, Vol. 30 No. 4, pp. 378-91, available at: www.ontopia.net/
topicmaps/materials/tm-vs-thesauri.html (accessed July 20, 2010).
Geddes, J.R. and Harrison, P.J. (1997), “Evidence-based psychiatry: closing the gap between
research and practice”, British Journal of Psychiatry, Vol. 171 No. 9, pp. 220-5.
Gerhart, S. (2004), “Do web search engines suppress controversy?”, First Monday, Vol. 9 No. 1.
Gross, T. and Taylor, A.G. (2005), “What have we got to lose? The effect of controlled vocabulary
on keyword searching results”, College & Research Libraries, Vol. 66 No. 3, pp. 212-30.
Gunnarsson, M. (2011), “Classification along genre dimensions: exploring a multidisciplinary
problem”, dissertation, Valfrid, Bora˚s, available at: http://bada.hb.se/handle/2320/7920
(accessed May 11, 2011).
Hjørland, B. (1992), “The concept of ‘subject’ in information science”, Journal of Documentation,
Vol. 48 No. 2, pp. 172-200.
Hjørland, B. (1997), Information Seeking and Subject Representation. An Activity-Theoretical
Approach to Information Science, Greenwood Press, Westport, CT.
Is classification
necessary after
Google?
315
Hjørland, B. (2007a), “Arguments for ‘the bibliographical paradigm’. Some thoughts inspired by the
new English edition of the UDC”, Information Research, Vol. 12 No. 4, paper colis06,
available at: http://informationr.net/ir/12-4/colis/colis06.html (accessed November 13, 2010).
Hjørland, B. (2007b), “Semantics and knowledge organization”, Annual Review of Information
Science and Technology, Vol. 41, pp. 367-405.
Hjørland, B. (2008), “What is knowledge organization (KO)?”, Knowledge Organization, Vol. 35
Nos 2/3, pp. 86-101.
Hjørland, B. (2009), “Concept theory”, Journal of the American Society for Information Science
and Technology, Vol. 60 No. 8, pp. 1519-36.
Hjørland, B. (2010), “The foundation of the concept of ‘relevance’”, Journal of the American
Society for Information Science and Technology, Vol. 61 No. 2, pp. 217-37.
Hjørland, B. (2011a), “Evidence based practice: an analysis based on the philosophy of science”,
Journal of the American Society for Information Science and Technology, Vol. 62 No. 7,
pp. 1301-10.
Hjørland, B. (2011b), “The periodic table and the philosophy of classification”, Knowledge
Organization, Vol. 38 No. 1, pp. 9-21.
Hjørland, B. and Kyllesbech Nielsen, L. (2001), “Subject access points in electronic retrieval”,
Annual Review of Information Science and Technology, Vol. 35, pp. 3-51.
Hodge, G. (2000), Systems of Knowledge Organization for Digital Libraries. Beyond Traditional
Authority Files, Council on Library and Information Resources, Washington, DC, available
at: www.clir.org/pubs/reports/pub91/contents.html (accessed May 16, 2011).
Hulme, E.W. (1911), “Principles of book classification”, Library Association Record, Vol. 13,
pp. 354-358, 389-94, 444-9.
Introna, L. and Nissenbaum, H. (2000), “Shaping the web: why the politics of search engines
matters”, The Information Society, Vol. 16 No. 3, pp. 1-17, available at: www.nyu.edu/
projects/nissenbaum/papers/searchengines.pdf (accessed June 7, 2007).
Lancaster, F.W. (2003), Indexing and Abstracting in Theory and Practice, Library Association,
London.
Larson, R.R. (1991), “The decline of subject searching: long-term trends and patterns of index use
in an online catalog”, Journal of the American Society for Information Science, Vol. 42 No. 3,
pp. 197-215.
Leydesdorff, L. (2006), “Can scientific journals be classified in terms of aggregated
journal-journal citation relations using the Journal Citation Reports?”, Journal of the
American Society for Information Science and Technology, Vol. 57 No. 5, pp. 601-13.
McIlwaine, I.C. (2010), “Universal decimal classification (UDC)”, in Bates, M.J. and Maack, M.N.
(Eds), Encyclopedia of Library and Information Sciences, 3rd ed., Vol. VII, Taylor
& Francis, London, pp. 5432-9.
Mai, J.-E. (2000), “The subject indexing process: an investigation of problems in knowledge
representation”, unpublished doctoral dissertation, The University of Texas, Austin, TX,
available at: http://individual.utoronto.ca/jemai/Papers/2000_PhDdiss.pdf (accessed July
20, 2010).
Mai, J.-E. (2011), “The modernity of classification”, Journal of Documentation, Vol. 67 No. 4,
pp. 710-30.
Maniez, J. (1997), “Database merging and the compatibility of indexing languages”, Knowledge
Organization, Vol. 24 No. 4, pp. 213-24.
Olson, H.A. (2001), “The power to name: representation in library catalogs”, Signs, Vol. 26 No. 3,
pp. 639-68.
JDOC
68,3
316
Olson, H.A. (2002), The Power to Name: Locating the Limits of Subject Representation in
Libraries, Kluwer Academic, Dordrecht.
Ørom, A. (2003), “Knowledge organization in the domain of art studies – history, transition and
conceptual changes”, Knowledge Organization, Vol. 30 Nos 3/4, pp. 128-43.
Ovesen, J. (1989), “Classificare necesse est. Lidt om klassifika-tion i antropologi-en – og ogsa˚
ellers (Classification is necessary. A little about the classification of anthropology – and
also in general)”, in Harbo, O. and Kajberg, L. (Eds), Orden I Papirerne – En Hilsen Til J.B.
Friis-Hansen, Danmarks Biblioteksskole, Copenhagen, pp. 117-22.
Pattuelli, M.C. (2010), “Knowledge organization landscape: a content analysis of introductory
courses”, Journal of Information Science, Vol. 36 No. 6, pp. 812-22.
Pors, N.O. (2005), “Studerende, Google og Biblioteker: En Undersøgelse af 1694 Studerendes Brug
af Biblioteker og Informationsressourcer”, Biblioteksstyrelsen og Danmarks
Biblioteksskole, København, available at: www.statensnet.dk/pligtarkiv/fremvis.
pl?vaerkid¼45550&reprid¼1&iarkiv¼1 (accessed May 16, 2011).
Riesthuis, G.J.A. and Bliedung, St. (1991), “Thesaurification of the UDC”, Tools For Knowledge
Organization and the Human Interface, Vol. 2, Index Verlag, Frankfurt, pp. 109-17.
Rowley, J.E. and Farrow, J. (2000), Organizing Knowledge: An Introduction to Managing Access
to Information, 3rd ed., Gower, Aldershot.
Sparck Jones, K. (2005), “Revisiting classification for retrieval”, Journal of Documentation, Vol. 61
No. 5, pp. 598-601.
Salton, G. (1996), “Letter to the editor. A new horizon for information science”, Journal of the
American Journal for Information Science, Vol. 47 No. 4, p. 333.
Scerri, E. (2007), The Periodic Table, Its Story and Its Significance, Oxford University Press,
Oxford.
Shachaf, P. (2009), “The paradox of expertise: is the Wikipedia reference desk as good as your
library?”, Journal of Documentation, Vol. 65 No. 6, pp. 977-96.
Soergel, D. (1985), Organizing Information: Principles of Data Base and Retrieval Systems,
Academic Press, Orlando, FL.
Soergel, D. (2009) “Digital libraries and knowledge organization”, in Kruk, S.-R. and McDaniel, B.
(Eds), Semantic Digital Libraries, Springer, Berlin, pp. 9-39, available at: www.dsoergel.
com/NewPublications/SoergelDigitalLibrariesandKnowledgeOrganization.pdf (accessed
May 16, 2011).
Stamos, D.N. (2004), “Book review of: Discovery and Decision: Exploring the Metaphysics and
Epistemology of Scientific Classification”, Philosophical Psychology, Vol. 17 No. 1, pp. 135-9.
Svenonius, E. (2000), The Intellectual Foundation of Information Organization, The MIT Press,
Cambridge, MA.
Villen-Rueda, L., Senso, J.A. and Moya-Anegon, F. (2007), “The use of OPAC in a large academic
library: a transactional log analysis study of subject searching”, The Journal of Academic
Librarianship, Vol. 33 No. 3, pp. 327-37.
Corresponding author
Birger Hjørland can be contacted at: bh@iva.dk
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