In the latter case, one will present one's semantics as a purely formal structure which may be assigned different interpretations without affecting the formal essence. For this, one may relate the different ontologies in terms of different degrees of specialization or generalization. The choice between the four different types of semantics depends on the intended application. In logic, the term proposition hasacquired a special use, representing sentences which do not require knowledge of the utterance situation for their interpretation. This problem shows up in the distinction between absolute and contingent propositions.
Absolute propositions express scientific or mathematical contents.
This requires that the parameters of origin be known, i.e. the location, the time, the person of the speaker, and the person addressed. The characteristic properties of contingent propositions correspond to a natural notion of truth, represented by the truth values true c and false c . Intuitively, a contingent proposition such as The Persians have lost the battle may be regarded as true c , if the speaker is an eyewitness who is able to correctly judge and communicate the facts, or if there exists a properly functioning chain of communication between the speaker and a reliable eyewitness. Otherwise it is evaluated as false c . Ontological foundations of natural and logical truth Figure 3.