Helpful Answers to Modal and Hypothetical Questions

HELPFUL ANSWERS TO MODAL AND tlYPOTHETICAL QUESTIONS Amre De Roeck, Richard Ball, Keilh Brown, Chris Fox, Marjolein Groefsema, Nadhn Obeid, Ray Turner University of Essex England emaih derce@uk.ac.essex (janet) 1.0 ABSTRACT, This paper describes a computational pragmatic model which is geared towards providing helpful answers to modal and hypothet- ical questions. The work brings together elements from fonnal. semantic theories on modality m~d question answering, defines a wkler, pragmatically flavoured, notion of answerhood based on non-monotonic inference aod develops a notion of context, with- in which aspects of more cognitively oriented theories, such as Relevance Theory, can be accommodated. The model has been inlplemented. The research was fundexl by ESRC grant number R000231279. Keywords:Semantics, Pragmatics 2.0 INTRODUCTION. Answers people give to questions have two basic properties: they may vary dependitig on the situation a question is asked in, and, especially if the answer is negative, they aim to be "helpful". The context-sensistivity of answering seems obvious and in no need of further demonstration. What precisely constitutes "help- fidness" is harder to pin down. Modal and hypothetical questions offer an interesting mea for investigating "helpfulness". Suppose A and B are going to a party and are discussing how they might travel. Suppose A asks B Cat, youdrive.? B is correct but perverse to respond ~ if he knows how to drive, has a valid licence but has no car, or if he has a car but he has lent it to someone. A more helpful answer might be No. because 1 haven't got a car. Note here that there is a range of "correct" answers, some of which are Ye___~s: for instance Yes, I hww how to drive, Yes, ! lutve a licence, even Yes, I have a car', and some of which are N._oo, as in No, I ha- ven't got a car" tonight. The range includes No, but ! cat, ask tO borrow my wife's car, or even Yes, ill .can get mF car back which establishes a link with hypothetical questions. Note also that, for each of these "correct" aqswers, we can imagine contexts in which they would be "helpful". Little is known ahout the nature of questions and their relation- ship to appropriate answers, or about how ,such answers can be computed given some information about what the answerer knows. Some theories, mainly emerging from the Men*ague tra- dition (see Groeneudijk and Stockhof 119841), attempt to define "sema,tic" answerhood (see section 2.2), but fall short when tackling the pragmatic aspect of helpful answers. Other theories lSperber & Wilso, 19861 offer interesting pragmatic insights but their formulation does not allow for a straightforward hnplemen- ration. Furthermore, the problem of answering modal and hypo- thetical questions is a compounded one which touches on a host of issues including quantification, intensionality, partiality, belief revision, propositional attitudes, etc. Our research aimed to draw up a formally specified and compu- rationally feasible pragmatic theory which could accommodate formal semantic views on answerhood as well as intuitive in- sights into "helpfulness" and its …

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