Proceedings of ConSOLE XX, 2012, 105-129 http://www.sole.leidenuniv.nl © Mikhail Knyazev A theta-theoretic account of the distribution of sentential complements The case of Russian čto-clauses Mikhail Knyazev In this paper I show that thematic structure alternations (agentive/nonagentive subject alternation and animate/inanimate object alternation) affect realization of a sentential complement. I present a theta-theoretic account of these effects based on Reinhart’s (2002) Theta system and its extensions proposed by Marelj (2004). The main intuition behind the proposed account is that a sentential complement is blocked whenever it is thematically indistinguishable from any of its co-arguments. 1. Introduction Since Pesetsky’s (1982) seminal discussion, it has been largely assumed that the distribution of sentential complements is governed by s(emantic)-selection, that is, sentential complements are expected to occur wherever they satisfy semantic requirements imposed by the matrix predicate. In this paper I show that the distribution of sentential complements (čto- clauses) in Russian is sensitive to the overall thematic structure of the matrix predicate, including the thematic properties of its co-arguments. It is crucial to show that the effect of the thematic structure of a predicate on the realization of a CP complement is independent from the choice of a lexical entry so that a lexical selection approach cannot be invoked to account for the data. Consequently, I will be focusing on cases of variability of argument structure found within one and the same lexical entry. Consider the following example. Russian verb grozit’ ‘threaten’ in its agentive use can take both a CP complement and a DP marked with instrumental case, as in (1a), but it can only take the latter kind of complement in its nonagentive use, as in (1b). Given that a CP is compatible with the thematic role that it is supposed to receive in (1b) its unacceptability would appear mysterious under an s-selection account. (1) a. Nom AG threaten DP INS /CP b. Nom NONAG threaten DP INS /*CP In this paper I provide an account of this and other similar cases based on Reinhart’s (2002) Theta system and its extensions proposed by Marelj (2004). The choice of the framework is not necessitated by the data that I will be discussing but is partly explained by the fact that the