Vague language and precise measurement: the case of poverty

Economists have often attempted precise measurement of phenomena which involve vague predicates. Difficulties emerge in such attempts if vagueness is not explicitly acknowledged at the methodological level. In this paper, various accounts of vague concepts are used to think about the economics of poverty measurement. Approaches to dealing with vagueness in this context tend to involve 'epistemic' and 'fuzzy set theoretic' approaches. Indeed, only the fuzzy set theoretic literature takes on vagueness explicitly. It is argued that both these approaches encounter significant difficulties, and that fuzzy set theoretic measures are hard to interpret intuitively. A 'supervaluationist' approach to the vagueness of poverty is developed. It is argued that this approach has much to recommend it and that some fuzzy measures can be interpreted intuitively as measures of vulnerability on this account.