Abstract :
Ever since computers were introduced people have wanted to make them easier to use, and to make them available to a wider range of people. A natural model of interaction, especially when the machine is intended for general use and has some pretensions towards intelligent behaviour, is a dialogue. This dialogue may be written form or in spoken form. In either case the form of the dialogue tends to resemble spoken English, rather than, say a series of memos or letters. So we may take the desire to converse with the computer, as one would with another person, as a widespread and reasonable goal. The author discusses what the role of theory is in achieving such a goal. He concludes that conversational natural language interaction relies on theories to be drawn from a variety of disciplines: linguistics to get the form of expression right; philosophical theories of meaning to get the propositional content right; theories of different modes of discourse to get the structure and strategy right, and others, such as theories of etiquette which will fine tune the form of expression. Any or all of these elements can be and are faked in systems, but without them the system will always non-gracefully collapse in the face of a perverse interlocutor
