Syntactic consequences of ellipsis identity: the case of pronouns and polarity items

After briefly reviewing the evidence that elliptical identity is stated over syntactic phrase markers (especially from the domain of voice mismatches in VP-ellipsis, sluicing, and pseudogapping), I explore the consequences for our understanding of pronominal interpretations and for the domain of polarity items. In particular, I re-examine cases of so-called "vehicle change" like "Every boy kissed his mother when she told him to.", in which naive syntactic identity would result in the ungrammatical, Principle C- violating "...when she told him to kiss his mother". I then turn to famous cases like "John didn't see anyone, but Mary did" (from Ross, Sag, etc). In both cases, it seems plausible to revive, in modern guise, something along the lines of Klima's "some~any" rule; applying this in the pronominal domain is much trickier, but may be compatible with recent proposals by Elbourne and Kratzer (and Kayne) that phi- and other pronominal features are contingent, not inherent, properties of DPs in certain positions.