In this talk I will investigate some problems posed by analysing the argument structure of impersonal and passive constructions in Estonian. I assume that the impersonal affix constitutes the syntactic satisfaction of the highest argument of a verb, which gives rise to an interpretation of a generalised referent. The question will be raised of why in some instances the impersonal affix is grammatical in contexts where a personal nominal or pronominal argument is ungrammatical.
This mismatch occurs in cases of impersonal perfective clauses, with intransitive verbs and transitive non-aspectual verbs. The periphrastic perfective verb form allows the addition of an impersonal affix onto the auxiliary verb, thereby impersonalising an already impersonal construction. I will present some straightforward examples of this alongside less clear examples, which are frowned on by prescriptivists but judged grammatical by other native speakers. I will attempt to formulate an account of the argument structure of these constructions, involving questions about the orientation of participles, the nature of passive arguments in Estonian, and the argument structure of auxiliaries.