John Buridan was born in Béthune in Picardy, in northern France, in the late 1290s. He spent his entire academic career in the arts faculty at the University of Paris, dying around 1360. In this regard, his career was unusual. Most other scholars either joined one of the religious orders (John Duns Scotus and William Ockham were Franciscans, Paul of Venice an Augustinian), or at least proceeded from their studies in arts to one of the higher faculties, usually theology (Scotus and Ockham did, as did Walter Burley, Thomas Bradwardine, William Heytesbury, and many others). Many of their works on...

Perhaps no science has known more vicissitudes than logic. One of the first to be created and assiduously cultivated by the Greeks, transmitted by the Syrians to Arabic-speaking peoples, it was able, despite being reduced to some elementary texts, to traverse the High Latin Middle Ages to blossom in the twelfth century and experience at the end of the thirteenth a flowering comparable to that which it has experienced in our own time. Then, toward the end of the fifteenth century, in one or two generations, it disappeared almost entirely. For more than three hundred years, one finds under the...

In this book I wish to treat of consequences by recording their causes, [p. 17]¹ as far as I can, about which much has already been adequately demonstrated by others. But they have not in point of fact been reduced to the first causes by which [those consequences] are said to hold. It will be necessary first to set out some assumptions.

In this first chapter I want in fact to make clear why a true proposition is said to be true, and a false one false, and a possible one possible, and an impossible one impossible, and a necessary...

In this second book, [p. 56] we will treat a particular kind of consequences, namely, between modal propositions. We set down some assumptions about them.

For first we take it that although many [different] modes occur in modal propositions, the main ones of which Aristotle and other masters have treated are modals of possibility and impossibility, of necessity and contingency, and of truth and falsity. So I intend only to treat of these.

But it should be noted that propositions are not said to be of necessity or of possibility in that they are possible or necessary, but from the...

Next, in this third book [p. 79], we will treat syllogistic consequences, about which we must set down a number of assumptions.

First, that there are many kinds of consequences. For some hold only because of their matter, so that they are not formal: for example, enthymemes, inductions, and examples,¹ and perhaps many others—for instance, if from an impossibility you infer whatever you please. None of these deserves to be called syllogisms.

Now among formal consequences some are from one simple subject-predicate to one simple subject-predicate [proposition], and then it is necessary for them to contain both terms besides...

Finally, in Book IV, [p. 111] we will consider syllogisms between modal propositions.

First, it should be remembered that some modals are composite and some divided. The subject in all divided [propositions] of necessity or of possibility is ampliated to supposit for what can be unless the ampliation is prevented by the extra phrase ʺthat which isʺ attached to the subject. So those in which the extra phrase is not added are called ʺof possibilityʺ or ʺof necessityʺ simply, while those in which the extra phrase is added are called ʺof possibilityʺ or ʺof necessity for those which are.ʺ

It...