UDC Consortium

UDC Philosophy Revision Report 1

version 1: 2009.08.07
by Claudio Gnoli

Please address any comment to italia@udcc·org


The author of this report has been charged by the UDC Consortium to study the possibility of a revision of class 1 "Philosophy", of the Universal Decimal Classification. The starting assumptions for this study are the following:

In order to explore the situation and discuss possibilities of revising class 1, since the beginning of 2009 the author has gathered an informal working group composed of people knowledgeable in both philosophy and classification. As a remarkable fraction of these people happened to be Italian, this has been the occasion for creating of a telematic mailing list "UDC Italia" <italia@udcc·org> and a related Web space <italia.udcc.org>, both hosted by the UDC Consortium. This group communicates mainly in Italian, and is also hoped to encourage a resumption of interest and activity on UDC in this country.

A starting general discussion has taken place through the mailing list from February to April 2009, with active participation by the following people: Philippe Cousson, Francesco Di Giuseppe, Claudio Gnoli, Ia McIlwaine, Roberto Poli, Alan Pritchard, Riccardo Ridi, Aida Slavic, Chiara Zara. Discussions have been helpful in outlining several basic problems and options, which are synthezized and further developed in this report. The Web space is being used to collect information useful for the revision study, including access to the mailing list, schemes, drafts, bibliography, and related sources.

Scope of class 1

It has been agreed that 159.9 "psychology" will be moved away of philosophy. Several people have suggested that 13 "The paranormal. The occult. Psi phenomena" should be moved away as well, as it seems to be connected more with religion than with philosophy. On the other hand, revision of class 2 has been completed recently, and it should be verified whether paranormal could find place in it.

Faceted structure

All involved people agreed that the revised class should have a fully faceted structure. This implies a relatively substantial revision of several parts of the class, by application of the principles of facet analysis, rather than just a shallow update.

Facets are variously represented in UDC by the following notational zones:


The last form is being increasingly abandoned. '1/'9 is used only in case that more than 9 facets are needed: as it will be seen, this is probably not the case with philosophy. Therefore, notation -1/-9 is chosen to express facets in class 1.


In facet analysis, each facet expresses a characteristic of division in its class, and at the same time can be reconnected to a general semantic category. For example, "teachers" can be a facet of the class of education, and at the same time belong to the general category of Agents.

There are several lists of general categories for classification, including that by Ranganathan (Personality, Matter, Energy, Space, Time) and that by Vickery and other members of the Classification Research Group (Thing, Kind, Part, Property, Material, Process, Operation, Patient, Agent, Space, Time). Such lists also work as guide for the citation order of facets, following the inversion principle: facets listed later in the schedules (hence represented by symbols of greater ordinal value) are cited first within a single compound classmark.

UDC still lacks any list of general categories, because its development in the direction of facetization is recent. It is suggested that such list can be defined now. Indeed, the present moment is a historical occasion for it, as several classed are being revised according to facet analysis. It is desirable that they all conform to a common model for purposes of consistency throughout the whole system.

In order to favour the development of such reference list of categories, facets of philosophy will be defined in such a way to conform as much as possible to facets of religion performing the same syntactical role. This is relatively easy, as religion and philosophy are akin domains. On the other hand, general categories have exactly the task to provide some consistency across a general system, which should allow to apply them in very different classes as well.

It is proposed that the UDC notational zone -1/-9 assumes the value of the following general categories, which will be followed in this revision proposal and are consistent with use in the revised class 2:

	-9	Kind
	-8	Property
	-7	Part
	-6	Process
	-5	Operation
	-4	Patient, Purpose
	-3	Agent
	-2	Tool, Material
	-1	Theory?

As it can be seen, these categories mostly conform to the list by Vickery or modifications of it, that are used among other systems in the second edition of the Bliss Bibliographic Classification (BC2). This is not surprising, as revision of the UDC religion class was in charge of Vanda Broughton, an editor of BC2 and a member of the Classification Research Group, who has applied them to the revision of UDC class 2 and the related FATKS project. On the other hand, some categories have been modified on the basis of experience with the Integrative Level Classification (ILC) research project, which uses a different set of general categories [Gnoli 2008]. In particular, the category of Purpose is considered necessary, and is assimilated to the notion of patient into a more general category; Tools are separated by Agents and assimilated with Materials, which are moved here from their original position after Property; the additional category of Theory is suggested by Broughton & Slavic [2007].

These categories are complemented in UDC with those expressed by existing common auxiliaries, including Place and Time as in Ranganathan's and Vickery's lists:

	-05	Common persons
	-04	Common relations, processes, and operations
	-03	Common materials
	-02	Common properties
	"1/9"	Time
	(=1/9) Ethnic group
	(1/9)	Place
	(0)	Form
	=	Language

Facets of philosophy

One basic step in the revision study is to identify the facets needed to express the contents of philosophical knowledge appropriately. To this purpose, one starting point was provided by examination of the facets of philosophy in existing classifications, in particular BC2. Another kind of source has been reflection and discussion within the working group. As claimed in facet analysis theory, facets of a domain emerge inductively, by looking for appropriate semantic/syntactic groups into which the concepts occurring in documents of the domain can be organized. In the case of the present revision, these concepts are provided first of all by subclasses of the existing version of UDC. Some of them, like 101.8 "methods of philosophizing" or 14 "Philosophical systems and points of view", should clearly be reorganized into separate facets. The identification of facets and of syntactical relationship between them is the result of interaction between this inductive process and the deductive guideline provided by general categories.

As a first draft, the following facets of philosophy have been identified:

Citation order of facets

As each of the facets above is reconnected to a general category, the standard order of categories determines the order of facets. The facets of philosophy seem to be connected with the following corresponding categories, given in square brackets, hence taking notation given on the left:

	10/19	Branches. Fields [Things]
	1-9	Systems. Schools. Traditions. Periods. History [Kinds]
	1-8	Viewpoints. Standpoints. Doctrines. Approaches. Theories. Possible philosophical attitudes. System typology. Isms [Properties]
	1-7	Topics. Special philosophies. Domain philosophies. Philosophy of special subjects [Parts]
	1-6	Development. Interactions [Processes]
	1-5	Practice. Method. Argumentation [Operations]
	1-4	Applications. Applied philosophy [Patients. Purposes]
	1-3	Philosophers. Promoters. Person and vocation of the philosopher [Agents]
	1-2	Sources. Materials [Tools. Materials]

This means that documents would be listed primarily by branches, then by systems, then by viewpoints, and so on. Branches are also the main characteristic of division in current class 1, so having it as the Things facet would help in limiting changes.

On the other hand, division by systems looks as a reasonable alternative. The UDC class of religion, sharing many points of contact with philosophy and recently revised, is divided primarily into systems. Still, several members of the discussion group have observed that primary division by systems, that divides philosophy into a conventional number of traditions rather than considering it as an autonomous science with its own subjects, would reflect an outdated conception of philosophy and is not desirable.

Based on these considerations, the first division by branches has been kept in the current draft, while systems are treated as Kinds and assigned the second position in the citation order. For example, a work about positivist ethics would be filed under 17 "ethics", and further specified by the system facet "positivism", rather than the opposite. No other facet seems to be worth of taking the first position (that is, the role of Things) in the citation order.

Special philosophies

One point arising in the discussion has been how to represent special philosophies, such as "philosophy of law", "philosophy of science" or "philosophy of art", which occur in a significant amount of literature. Currently these are not represented in specific subclasses of 1, but under the specific subjects by colon combinations such as 7:1 "arts [in some relation to] philosophy", or 34:1 "law [in some relation to] philosophy".

However it has been noticed that the last meaning is different from "philosophy of law". Indeed, colon relationship itself does not express the kind nor the direction of the link between the two concepts. While 34:1 means "law in relation to philosophy", it may be useful also to have a way to express "philosophy of law", that is, to treat law (or any other subject) as a topic of philosophy. In fact, the function of facets is representing the most typical relationships within a field, thus covering a semantic and a syntactic meaning at the same time.

Therefore, it is proposed that a facet for topics be used, as a manifestation of the general category of Parts, in the sense that topics are special parts of the whole subject coverage of philosophy, consisting of all aspects of life and knowledge.

Place of definition of facets

This, in turn, poses the problem of how to combine notation for the topic facet 1-7 with notation for the particular facet value (the focus) law. As law has its own notation 34 in the general schedule of UDC, it would be desirable that this be used in combination with 1-7 in order to produce the combined meaning "philosophy of law". However, the two pieces of notation cannot be attached directly, like in 1-734, as this would give no hint to computers and humans for parsing the classmark, and a search for 34 would not retrieve it. Some indicator that the facet is composed from an existing class is needed.

This is a case of what have been identified as extra-defined facets, that is, facets of which foci consist of existing classes taken from other parts of the scheme [Gnoli 2006]. These are opposed to context-defined facets, having foci that only appear in the context of the present facets and have no independent meaning: while "positivism" only appears in the system facet of philosophy, which is its place of unique definition, "law" also appears as an autonomous class. Extra-defined facets are distinguished from context-defined ones in the ILC project, which provides a source for considering this problem.

As indicator of extra-defined foci, an obvious solution is offered by the colon: "philosophy of law" could be represented as 1-7:34. Notice, however, that this implies that the colon is not given a meaning of phase relationship, as in theory of facet analysis phase relationships have a more general value than facets, that is, facets belong to phases rather than the opposite [Ranganathan 1967]. If the colon were interpreted as a phase relationship, a number like 1-7:34-654 would be parsed into the phases 1-7 and 34-654, which is not the intended meaning of our example. To avoid this, two solutions are hypothesized:

Extra-defined foci can be shortened in ILC by a mechanism of default main class [Gnoli 2006]. This concurs to produce shorter combined classmarks, though requiring that computers be instructed to intepret the shortened focus in the correct way for purposes of automatic information processing. As the trend with UDC is to consider automatic processing more important than brevity of notation, this kind of device will not be implemented for the proposed faceted classes of UDC.

It is highly advisable that more than one facet is allowed to be combined in the same classmark, as in the example just given, and as done already in revised class 2. Indeed, imposing that only one facet can be expressed at a time would mean missing some of the main advantages of facet analysis. Classmarks with multiple facets can be easily retrieved in digital sources, by the simple instruction of inserting a wildcard before each facet indicator: so that a search for 1-43 would be interpreted as 1*-43* and would also retrieve the multi-facet classmark 1-76:5-43-2:1. The other option, of expressing each facet by repeating the main class 1 and connecting all them by colons, would produce awkward classmarks like 1-76:1-43:1-2, which would:

Development of the study

The current study is expected to collect more ideas and suggestions from the UDC Round Table and Seminar planned in The Hague for October 2009, and from other feedbacks to the present report. This can induce some modifications in the current draft structure. The next steps will be to pay more attention to the details of classes and subclasses, and to the update of terminology and presentation of the schedule. All these components are expected to be included in a final proposal for revision of class 1.


Broughton V, Slavic A, 2007, Building a classification for the humanities: principles and procedures, Journal of documentation, 63.5, p. 727-754.

Gnoli C, 2006, The meaning of facets in nondisciplinary classifications in Budin G, Swertz C, Mitgutsch K, Knowledge organization for a global learning society: proceedings Ninth ISKO Conference, Vienna, Ergon, Würzburg, p. 11-18.

Gnoli C, 2008, Categories and facets in integrative levels, Axiomathes, 18.2, p. 177-192.

McIlwaine IC, Williamson NJ, 2008, Medicine and the UDC: the process of restructuring, in Arsenault C, Tennis JT eds, Culture and identity in knowledge organization: proceedings Tenth International ISKO Conference, Montréal, Ergon, Würzburg, p. 50-55.

Ranganathan SR, 1967, Prolegomena to library classification, 3rd ed., SRELS, Bangalore.


UDC Philosophy Revision Report 1 / Claudio Gnoli = (UDC Consortium. Gruppo di lavoro Italia) – <http://italia.udcc.org/report1.html> : 2009.08.07 -