On Reduplication is a study of the logical properties of reduplicative propositions, that is, of propositions having qualifications, like 'Christ qua God is a creature' and 'being qua being is the subject of metaphysics'. The focus is on what ways qualifications change the truth value and the inference patterns of simple, categorical propositions. The central class of reduplications is that in which the qualifications are introduced by a qua connective like 'qua', 'insofar as', 'under the concept of', or 'in virtue of the fact that'. Reduplicative propositions...