Ex impossibili quodlibet sequitur

_ Source: _Volume 53, Issue 2-4, pp 353 - 371 While agreeing with Professor D’Ors’ thesis that the notion of logical consequence cannot be exhaustively characterized, I depart from Professor d’Ors’ conclusion that the very notion of good consequence is primitive and can only be identified with the set of acceptable rules of inference, and from his conviction that modal notions such as necessity and impossibility are equivocal and gain such clarity as they have by their interaction with rules of inference. Inspired by this picture, Professor d’Ors undertook an examination of a number of medieval attempts to analyze the notion of consequence and tried to show how certain developments in the medieval history of logic made sense in the light of debate over such analyses. This paper examines a small fragment of Professor d’Ors programme and its relation to some aspects of Jean Buridan’s account of the consequence relation