The syntactic rules of today's High German are generally thought to have crystallized during the 18th century. One can therefore expect that during that time the processes of grammaticalization had a particular influence on doubtful cases in the usage of language. The syntactic development varied from region to region and was accompanied by theoretical controversies. One of the controversial issues was word order. The debates focused primarily on the order in verbal complexes and on the possibility of extraposing simple components and dependent clauses. This paper is based on the assumption that the theoretical controversies in some way reflected the doubtful cases in the usage of language. In order to identify the actual variants, the theoretical controversies will be outlined first. Then the analysis will focus on whether and how these variants were used in a corpus of 18th century texts. The objective is to determine the language-internal, sociological, and geographical factors of the variants' usage and thus to model the situations in which the doubtful cases ocurred. In conclusion, the following issues will be discussed: the relationship between the doubtful cases and diachronic language developments, the language-external factors of the doubtful cases, and the approach of language theorists to doubtful cases.