Knowledge Science - Natural and Artificial Reasoning - page 45

Table 4.2 The role of truth in declarative knowledge
Types of declarative knowledge Truth of the knowledge dependent upon

Fact Observation, deduction or belief

Distinction (taxonomic) Convention or definition

Hypothesis Convenience

4.2.2.2 Taxonomic

The taxonomic class of concept consists of propositions that define general features,
classes, categories, or types of objects or events. Taxonomic knowledge is concerned
with the distinctions made in a domain.
These propositions are identified by the nature of the knowledge in that they are
'true' by convention or by definition. For example, the truth of the statement that
“a bachelor is an unmarried man” depends upon a convention that the verbal token
“bachelor” should represent the class of persons who are male and unmarried.

4.2.2.3 Hypotheses

Hypotheses are propositions that express constraints, laws or rules about the world
rather than our modes of representing the world. Taking a pragmatic view, (Peirce
1958 , 1966 ) wrote “ Hypotheses are true if they are useful; they are useful if they
make the world a less surprising place”.
In conjunction with inference, hypotheses make predictions about the world so
as to reduce the effective information content of incoming messages from or about
the world. Without hypothesis formation, it would be impossible to develop new
concepts about the world: learning could not happen.
Table 4.2 summarises the distinctions between different types of declarative
knowledge. Note that the role of 'Truth' here is to characterise an abstraction of
the world that is person or people centred. Thus the set of facts, distinctions, and
hypotheses assert a view of the world that is in part influenced by the world itself
(observations), part by the individual (beliefs), part by society (conventions), and
part by purpose (convenience). 'Truth' reduces to a parameter that really has a role
only for deductive inference .
Hypotheses may be either theories or models. Although these are often repre-
sented visually, i.e., as visual hypotheses (Gooding 1992 ; Thagard and Hardy 1992 ;
Trumpler 1992 ), in the first instance I will only be concerned with the declarative and
verbal forms of hypotheses. Later we will wish to extend the notion of a hypothesis
to form part of a mechanism (a machine, or a physical structure or natural system).
Models, in conjunction with an inference system and heuristic knowledge, make
predictions about a limited part of the world, and are derived from theories and
perceptions that encompass a greater view than any model. Associated with a model
is a set of inference mechanisms so that the model may be activated (driven). Many