Categorical Logic is such a versatile tool that it allows to give an account uf both impredicative and predicatives systems. A topos is a categorical account to higher order logic and thus impredicative. A logos (Freyd) gives an account of intuit. first order logic and thus is "predicative". A locally cartesian closed category (after splitting) is a model of Martin-Loef type theory. That is predicative. Both predicative and impredicative universes can be defined categorically within lcc's. This was done is the second half of the 1980s by many people (including myself). Whether category theory itself is "impredicative" however is an ill-posed question in my eyes. Thomas [For admin and other information see: http://www.mta.ca/~cat-dist/ ]