Reasoning about Theory Formulation and Reformulation. A New Solution to the Qualification Problem

One of the main problems in formalizing common sense reasoning is the qualification problem, i.e. the fact that the truth of many general sentences depends on a virtually infinite number of qualifications. Traditionally, this has been seen as the problem of computing the set of qualifications which are entailed by a given knowledge base, and then of expressing the conjecture that these are all the qualifications which must be considered. In this paper, we argue that a preliminary step should be that of restricting the focus on an adequate subset of a (potentially) very large knowledge base; that the adequacy of such a subset can only be conjectured depending on the formulation of the problem to be solved; and that this conjecture can be defeated whenever new information is added. We show how this can be achieved using a mechanism of ‘theory formulation’ and ‘reformulation’ in the framework of MultiContext Systems. As an anecdotal example, we present a solution to McCarthy’s Glasgow-London-Moscow problem