Information Technology Reference
In-Depth Information
Class realism . The class realist believes that classes actually exist in the world for anyone to discover.
The class realist attempts to discover the set of classes that exist in a domain by examining the domain;
and the validation criteria for a model created by a class realist is that it represent the classes as they
exist in the real world. There is no possibility that class formation is influenced at all by the cognition
of the observer, because the classes can be discovered and verified objectively. If class realism holds,
then there can only be one correct information model for any given domain - the one that accurately
models the real world. Although this metaphysical position is quite prevalent among information model-
ers, there is little philosophical support for it. It is a modern day version of Platonic idealism in which
classes exist in some nonmaterial world waiting to be apprehended by the intellect. Even Plato, who
originated the position, had quite a bit of trouble with it.
Class conceptualism . The class conceptualist believes that classes are constructed in the mind of the
observer through some cognitive process of abstraction based on cues derived from the real world. If
class conceptualism is correct, then class formation may be influenced by a wide variety of social and
cognitive factors that may influence the abstraction process. Further, validation becomes very difficult.
Since the model is the result of an abstraction process it is necessary to validate the resulting model us-
ing some criteria other than conformance to the real world. Philosophically, this position is more likely
to be correct. However, it brings a host of new problems into the practice of information modeling.
Attribute realism . The attribute realist believes that attributes or properties of individual entities exist in
the world independent of the cognition of the observer. Classes can then be formed by grouping entities
with like attributes. More rigorous approaches to information modeling adopt this position and there is
some justification for it under a limited set of circumstances. There are two forms of attribute realism,
limited and extended. Limited attribute realism suggests that entities have a limited set of properties
and like entities can be grouped according to the commonality of those limited properties. Extended
attribute realism suggests that entities have a virtually unlimited set of properties and groupings are
formed based on common subsets of properties. If extended attribute realism holds, then an abstraction
process occurs when a small set of like attributes are selected for the grouping process. Once again,
social and cognitive factors may influence the grouping process. And attribute selection must be guided
by modeling objectives.
Attribute conceptualism . The attribute conceptualist believes that attributes or properties of individual
entities are constructed, once again, through a cognitive process of abstraction guided by cues form the
real world. It may be reasonable to assume attribute realism in the case of physical properties of entities.
However, attributes of entities that are functional in nature or define relationships between entities are
almost certainly constructs. If attribute conceptualism holds, then attribute construction may also be
influenced by a wide variety of social and cognitive factors that may influence the abstraction process.
Once again, attribute construction, like class construction, would have to be guided by modeling ob-
jectives. Attribute conceptualism can be constructivist or re-constructivist. The constructivist defines
attributes based on cues from the environment largely based on the usage of terms in the language
of the domain. The re-constructivist has to redefine the set of attributes in order to make sense out of
conflicting usages.
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