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After a brief sketch of the state of Buridan studies, this review article examines the recent study, by Benoît Patar, of a commentary on Aristotle’s Physics that is generally attributed to Albert of Saxony, but which Patar believes to have been authored by John Buridan (the text is preserved in the manuscript Bruges, Stadsbibliotheek 477, fols. 60va–163vb, and was edited by Patar himself in 1999). Patar is utterly convinced that the Bruges Quaestiones represent Buridan’s prima lectura, that is, his first course of lectures on the Physics, which preceded the two other redactions that are traditionally attributed to him. However, there is no textual evidence in support of this assumption, but only speculative circumstantial evidence. The article therefore rejects Patar’s thesis as highly problematic.

This paper is an attempt to rethink from two perspectives Buridan’s ideas concerning knowledge: On the one hand, I explore Buridan’s theory of knowledge in the hope that it will shed some light on the intuition that the structure of propositions determines the justification of our beliefs on various different levels. On the other hand, I would like to contribute to demonstrating the consistency of Buridan’s thought,which has been remarked by almost all scholars working on Buridan: in particular, I am interested in exploring the benefits of using supposition theory when applied to the theory of knowledge. I will start by examining Buridan’s conception of scientia (as opposed to error, opinio and fides), from the perspective of two distinctions which are very important to Buridan’s theory of the proposition: complexio/enunciatio and enunciatio/assensus. Then I will recall Buridan’s analysis of propositions (and his use of supposition to define truth conditions) to show their consistency with this conception of knowledge.

I examine the theory of consequentia of the medieval logician, John Buridan. Buridan advocates a strict commitment to what we now call proposition-tokens as the bearers of truth-value. The analysis of Buridan's theory shows that, within a token-based semantics, amendments to the usual notions of inference and consequence are made necessary, since pragmatic elements disrupt the semantic behaviour of propositions. In my reconstruction of Buridan's theory, I use some of the apparatus of modern two-dimensional semantics, such as two-dimensional matrices and the distinction between the context of formation and the context of evaluation of utterances.

On the basis of passages from John Buridan's Summula Suppositionibus and Sophismata, E. Karger has reconstructed what could be called the ?Buridanian theory of inferential relations between doubly quantified propositions?, presented in her 1993 article ?A theory of immediate inference contained in Buridan's logic?. In the reconstruction, she focused on the syntactical elements of Buridan's theory of modes of personal supposition to extract patterns of formally valid inferences between members of a certain class of basic categorical propositions. The present study aims at offering semantic corroboration?a proof of soundness?to the inferential relations syntactically identified by E. Karger, by means of the analysis of Buridan's semantic definitions of the modes of personal supposition. The semantic analysis is done with the help of some modern logical concepts, in particular that of the model. In effect, the relations of inference syntactically established are shown to hold also from a semantic point of view, which means thus that this fragment of Buridan's logic can be said to be sound.

On the basis of passages from John Buridan's Summula Suppositionibus and Sophismata, E. Karger has reconstructed what could be called the ?Buridanian theory of inferential relations between doubly quantified propositions?, presented in her 1993 article ?A theory of immediate inference contained in Buridan's logic?. In the reconstruction, she focused on the syntactical elements of Buridan's theory of modes of personal supposition to extract patterns of formally valid inferences between members of a certain class of basic categorical propositions. The present study aims at offering semantic corroboration?a proof of soundness?to the inferential relations syntactically identified by E. Karger, by means of the analysis of Buridan's semantic definitions of the modes of personal supposition. The semantic analysis is done with the help of some modern logical concepts, in particular that of the model. In effect, the relations of inference syntactically established are shown to hold also from a semantic point of view, which means thus that this fragment of Buridan's logic can be said to be sound.

The medieval philosopher Jean Buridan says that at one time, he favored a solution to Liar−type paradoxes that relied on the claim that "every proposition, by its very form, signifies or asserts itself to be true."1 (I shall refer to this as Buridan's view, though he came to reject it when he wrote his Sophismata , in which he reports the view.) C.S. Peirce also suggested something like this in response to the Liar, and in a classic discussion of Buridan, Arthur Prior evinces great sympathy for the view (in contrast to his rejection of Buridan's official solution).2 But what exactly does it mean for an arbitrary proposition to assert itself to be true? And is it really a plausible view to hold that every proposition does assert itself to be true?

Buridan's life, works, and influence -- Buridan's logic and the medieval logical tradition -- The primacy of mental language -- The various kinds of concepts and the idea of a mental language -- Natural language and the idea of a formal syntax in Buridan -- Existential import and the square of opposition -- Ontological commitment -- The properties of terms (proprietates terminorum) -- The semantics of propositions -- Logical validity in a token-based, semantically closed logic -- The possibility of scientific knowledge -- Buridan's anti-skepticism -- Buridan's essentialist nominalism.

This edition of that chapter is intended to make Buridan's ideas and arguments accessible to a wider range of readers.