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As previously mentioned, ontologies developed within the AI community are often
directed to a specific domain of knowledge in a specific context, and are intended to be
implemented or defined within a specific software artefact. Examples are KIF (Genesereth
and Fikes, 1992), Ontolingua (Gruber, 1992; 1995), and OIL (Fensel, et al., 2000).
Recent work by AI researchers around the Semantic Web and the IEEE Standard Upper
Ontology (IEEE, 2003), and DOLCE (Gangemi, et al., 2002) is encouraging in that they
all recognise the central role of higher level ontologies in information systems.
It is the higher level reference ontologies and the basis for the selection of a particular
reference ontology for the creation of a domain specific ontology, directed towards in-
formation systems research, that is the concern of this paper.
Approaches to categorisation
The history of ontology goes back over 2000 years to Aristotle and his Categories. The
influence of his concept of hierarchical structures can be seen in many current categor-
isation schemes, ranging from the Linnaean schemes used in the life sciences to the
various library categorisation schemes of Dewey and the Library of Congress. The history
of the study of ontology has not been one of smooth progress with, for example, Kant
(1787, p. 80) even rejecting ontology as a valid area of study. Kant's attitude was based
on his belief that ontology was a synthetic a priori knowledge of things in general. Franz
Brentano (1933, p. 81) asserts that Kant completely misunderstood Aristotle's theory of
categories, approaching it without a sound understanding of Aristotle's point of view.
Rather than an a priori assumption, as Kant believed, Aristotle's categories were based
on empirical observations of being, of individuation and of collection into species.
Despite Brentano's rejection of Kant, some of his views regarding perception had simil-
arities. Brentano's ontology is based on the investigation of two types of phenomena.
First, he identifies our inner perceptions, facts about ourselves and our intentional
activity. Second, the sensations we have of the external world: colour, sounds, smells
are identified. In his comments on intentionality we begin to see a way of accommodating
perceived diversity:
However various our ideas of things may be, the differences of the ideas are
not just a function of the differences of the objects of thought; they are also a
function of what the object is thought of as . It is possible that the objects may
differ and yet that one and the same idea may serve to present either one of
them. And also conversely: one and the same object may be presented by two
ideas which differ with respect to the object (Brentano, 1933, p. 40 [emphasis
in original])
One of Brentano's students was Edmund Husserl, who continued investigations into the
concept of intentionality. In the course of this he created phenomenology, the key idea
of which is intentionality. Husserl identified problems with Brentano's approach when
dealing with serious misperception and hallucinations. In these cases, what is the object?
Husserl considered those features of consciousness that make it as if of an object. The
collection of all these features he called the act's noema. The noema includes all the ob-
ject's features, whether perceived or unperceived, including features we may take the
object as having without having ever reflected or paid attention to those features. Because
this is determined by perception you could, in a particular situation, see a man, but later
realise it was a mannequin, with a corresponding shift of noema. An example closer to
our research area might be Isaac Asimov's The endochronic properties of resublimated
thiotimoline (1948). This is written using the structure and language of a chemistry re-
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