In modern Swedish, the complementizer som must not be omitted in (restrictive) relative clauses when the relativised constituent is the subject. This was, however, possible in Old Swedish. Also in today's Swedish, again in contrast to Old Swedish, the complementizer som must follow a subject wh-pronoun in embedded clauses.
In this paper, it is argued that the development towards obligatory som is connected with other changes in Early Modern Swedish. The investigation of a very limited number of historical texts confirms the hypothesis, particularly concerning the relatives, in the sense that the changes coincide in time. Regarding the interrogatives, however, the picture is somewhat more complex.
1997. 171-178 p.