English exhibits a rich apparatus of tense, aspect, time adverbials and other expressions that
can be used to order states of affairs with respect to each other, or to locate them at a point in
time with respect to the moment of speech. Ideally one would want a semantics for these
expressions to demonstrate that an orderly relationship exists between any one expression and
the meanings it conveys. Yet most existing linguistic and formal semantic accounts leave
something to be desired in this respect, describing natural language temporal categories as
being full of ambiguities and indeterminacies, apparently escaping a uniform semantic description.
It will be argued that this anomaly stems from the assumption that the semantics of these
expressions is directly related to the linear conception of time familiar from temporal logic or
physics - an assumption which can be seen to underly most of the current work on tense and
aspect. According to these theories, the cognitive work involved in the processing of temporal
discourse consists of the ordering of events as points or intervals on a time line or a set of time
lines.
There are, however, good reasons for wondering whether this time concept really is the one
that our linguistic categories are most directly related to; it will be argued that a semantics of
temporally referring expressions and a theory of their use in defining the temporal relations of
events require a different and more complex structure underlying the meaning representations
than is commonly assumed. A semantics will be developed, based on the assumption that
categories like tense, aspect, aspectual adverbials and propositions refer to a mental representation
of events that is structured on other than purely temporal principles, and to which the
notion of a nucleus or consequentially related sequence of preparatory process, goal event and
consequent state is central.
It will be argued that the identification of the correct ontology is a logical preliminary to the
choice of any particular formal representation scheme, as well as being essential in the design
of natural language front-ends for temporal databases. It will be shown how the ontology
developed here can be implemented in a database that contains time-related information about
events and that is to be queried by means of natural language utterances
