Franciscus de Prato on Reduplication

Medieval logicians used to characterize as reduplicative those propositions in which occurs the Latin expression 'inquantum' (insofar as), or another expression equivalent to it, with the specific function of ‘duplicating’, as it were, the reference to a property of a given subject. If Socrates is a man, a typical reduplicative proposition is “Socrates insofar as (inquantum) he is a man is able to laugh”, where the expression ‘insofar as’ stresses that it is in virtue of the very property of being a man that Socrates is able to laugh. In other words, a reduplicative proposition in the proper sense emphasizes a condition that accounts for the attribution of a predicate to a subject. Logical fourteenth-century handbooks devoted an entire chapter to reduplicative propositions which, though categorical in form, together with exclusive and exceptive propositions, were shown to be logically equivalent to hypothetical propositions. The logical treatment of reduplicative propositions was of some weight in dealing with sophismata and insolubilia. In this paper we shall reconstruct and discuss the theory of reduplication elaborated by the Dominican philosopher Franciscus de Prato, who was active in Italy in the first half of the fourteenth century.