Stage and Individual-level predicates whithin "if" and "when" clauses: what works and what doesn't

Clauses headed by if and when are very often considered syntactically and semantically equivalent. Nevertheless, in this paper we show that the type of predicate has an impact both on the grammaticality and the interpretation of the subordinate clause in Spanish. Theses clauses provide evidence for the proposal that stage-level predicates involve an extra-argument that individual-level predicates lack. Following Kratzer (1995), we assume that this is extra-argument is a spatio-temporal argument. While stage-level predicates in the subordinate clause are perfectly grammatical, individual-level predicates yield to ungrammatical sentences, unless an indefinite or a kind-referring NP is involved. Kratzer´s Prohibition against vacuous quantification provides a sound account for the asymmetry between the two types of predicates. In addition, a stative verb in the when clause is grammatical, but it forces an epistemic reading. When both predicates are individual-level predicates in the subordinate and the main clause, the if clause may can take a factual reading while the when clause is ungrammatical unless there is some kind of operator involved through a generic, a kind-referring NP or an indefinite pronoun