predication vs. aboutness in copy raising

copy raising sentences (charlie looks like his prospects are bright) are ambiguous between a thematic and a nonthematic reading for the subject, corresponding to whether or not it is the perceptual source. on the basis of hebrew and english data, this paper motivates a novel generalization: a pronominal copy in the complement is necessary if and only if the matrix subject is not thematic. this follows if (i) a nonthematic dp must be licensed by predication, (ii) the clausal complement is turned into a predicate by merging with a null operator, and (iii) the pronominal copy is the variable required by the operator.