Authors/Ockham/Summa Logicae/Book II/Chapter 31

Latin	English
[2.31 DE PROPOSITIONE CONDICIONALI ET AEQUIVALENTE EI]	31: On the Conditional Proposition and its equivalent
Sequitur modo videre de istis in speciali. Sed quia condicionalis aequivalet uni consequentiae, ita quod tunc condicionalis est vera quando antecedens infert consequens et non aliter, ideo differatur usque ad tractatum de consequentiis.	It follows now to look at these propositions specifically. But because a conditional proposition is equivalent to a consequence, so that a conditional proposition is true when the antecedent implies the consequent and not otherwise, this point will be deferred until the tract on consequences.
Hoc tamen sciendum quod illa hypothetica dicitur condicionalis quae componitur ex duabus categoricis, coniunctis mediante hac coniunctione 'si' vel aequivalenti ei. Propter istud ultimum est dicendum quod ista est condicionalis 'Sortes non legit nisi sit magister', quia aequivalet isti 'si Sortes non sit magister, Sortes non legit'. Et universaliter, quando duae propositiones coniunguntur mediante aliqua coniunctione, et totum aequivalet uni condicionali, illa propositio dicetur hypothetica et condicionalis.	Yet it should be known that a hypothetical proposition is called conditional which is composed of two categoricals joined by the intermediary conjunction 'if' or something equivalent to it. Because of this last point it should be said that 'Socrates does not teach unless he is an instructor' is a conditional proposition because it is equivalent to 'if Socrates is not an master, Socrates does not teach'. And generally when two propositions are joined by some conjunction and the whole is equivalent to one conditional proposition, that proposition will be called hypothetical and conditional.
Est etiam sciendum quod ad veritatem condicionalis nec requiritur veritas antecedentis nec veritas consequentis, immo est aliquando condicionalis necessaria et quaelibet pars eius est impossibilis, sicut hic 'si Sortes est asinus, Sortes est rudibilis'.	It should also be known that for the truth of a conditional there is required neither the truth of the antecedent nor the truth of the consequent, indeed sometimes a conditional proposition is necessary and each part of it is impossible, as in 'if Socrates is a donkey, Socrates is capable of braying'.