Propositional clitic omission in Spanish and lack of knowledge

This article addresses anaphoric reference to clausally introduced propositions in Spanish. Although Spanish “canonically” uses the clitic lo as the direct object pronoun referring to these kinds of entities, its omission is also possible. This paper offers evidence showing that (lack of) knowledge on the part of the speaker about the full content of the proposition plays a role in the choice between the clitic lo and its omission: omission is possible (although not necessary) when the speaker lacks knowledge of the complete content of the proposition, whereas the opposite situation favors the use of the clitic lo. Quantitative and qualitative data supporting this idea come from the distribution of lo and its omission in the no (lo) sé ('I don't know') expression, the constructions no poder decir and no saber decir ('can't say') and the expression quién (lo) sabe ('who knows').