B. argues that language is not only restricted by the structure of the world, but that it also provides the means with which people tackle everyday problems in society. One of those means, reference, is further considered; it is shown what can happen if it is not used properly. Presupposition is discussed as a related topic. B. attempts to explain how information can be added correctly to a hearer's already existing world of knowledge: the speaker has to define a focus by means of presupposition and hehas to say something about that focused element.