HERBERT PAUL GRICE, "CONVERSATIONAL IMPLICATURE", The Oxford Lectures, 1966, BANC MSS 90/135c

Speranza

In this article, we first study abduction in human dialogues. Given an utterance, objective abduction produces a hearer’s belief that could explain the utterance, while subjective abduction produces a hearer’s belief that could explain the belief state of a speaker. Different types of abduction are formulated using propositional epistemic logic. We next consider conversational implicature used as pragmatic inference in speech acts. Two conflicting implicatures, Q-implicature and I-implicature , are formulated and contrasted with abduction. We also argue how speakers could use abduction or conversational implicature for the purpose of misleading hearers.