  Broadly speaking, Gassendi expresses some three notions of logic in the Syntagma. The first, enunciated in the history of logic section that appears immediately prior to the Institutio Logica, suggests a picture of logic along heuristic and didactic lines, in the manner of Ramus, whose theory Gassendi lauds as a guide to organizing and presenting existing knowledge (O I 59a-62b). The second suggests that logic consists in the Aristotelian syllogistic, the understanding thereof, and related methodological concerns. The third suggests that logic consists in the study and use of causal reasoning, and related methodological concerns—most notably including an exposition of regressus demonstrativa theory in the manner of Zabarella and Nifo (this notion expressly contradicts his Exercitationes view that such causal reasoning cannot be justified).  These latter two notions yield the main thrust of the Institutio (though the discussion of demonstration in Book IV has clear Ramist debts). They also have great currency for Gassendi, who typically crafts his use of syllogism and causal inference and method after his Institutio conceptions, or at least signals that he intends to do so. The same may not be said for his Ramist conception.  For although he makes ample use of rhetoric, he does not turn to definition, distribution, or division for the purposes of diagramming or expounding existing knowledge—per the logic of Ramus—in any way that matches his interest in the traditionally Aristotelian conception of analysis as problem-solving.