The dangerous "All" in specifications

Rupp and Gotz (see CONQUEST-1, 1st Conf. Quality Engineering in Software Technology, Nurnberg, Germany, 1997) observe that some, but not all, requirement specification sentences involving universal quantification, are dangerous because they are usually not true. Jackson and Zave (see Proc. Int. Symp. Requirements Engineering, IEEE Computer Society, p.56-64, 1993) provide a classification of requirement specification sentences into indicative and optative sentences. It is observed that the dangerous sentences involving universal quantifiers are all indicative.