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An Abstract
of the talk presented at IMLLAI
(International Meeting on Language, Logic, and Artificial Intelligence)
13 - 17 July, 1998, Fortaleza, Brazil
Tomoyuki Yamada
Hokkaido University
My long-term ambition is to develop a philosophically sound and mathematically rigorous theory of illocutionary acts that provides an empirically adequate treatment of speech atc phenomena both in English and in Japanese. In this talk, I shall present basic ideas of, and arguments for, a theory of Illocutionary acts which has the following features:
(1) It is "ascription-based" in the sense that its basic formulas are formulas ascribing actions to agents. They are used to state facts about particular utterances and illocutionary acts performed. The theory also contains, so to speak, higher order formulas stating constraints upon possible combinations of types of contexts, types of utterances, types of possiblle illocutionary acts, and types of backgroud conditions. It doesn't contain, however, formulas for giving commands, making promises, making requests, and so on. The language of this theory is not meant to be an all-purpose language in which all sorts of illocutionary acts could be performed, but is meant to be a special-purpose language for stating various theoretical assumptions, hypotheses and their results about speech acts performed in natural languages.
(2) It contains a general theory of content for illocutionary acts which is based on a generalized version of J. L. Austin's theory of Truth. By adopting Austin's notion of demonstrative conventions and descriptive conventions, it specifies contents of contentful illocutionary acts through specifying conditions of their satisfaction without appealing to the notion of propositions, and thus it enables us to avoid assuming propositions to be common contents of statements, commands, promises, and so on. It respects the intuition that commands and promises are not things which are true or false.
(3) It treats illocutionary acts as acts, i.e. that which change situations. It aims to characterise each illocutionary force in terms of types of changes in types of situations which illocutionary acts with that force bring about. Some such analysis would be needed if we are to view speech acts in the context of a general theory of action.
I shall adopt a version of the language of Situation Theory as the language in which to give precise formulations to a version of the theory with the features above. I shall also try to show how Searle and Venderveken's theoretical insights could be incorporated and utilised in this version of ascription-based theory.