συλλογισμός

Syllogism comes from Greek συλλογισμός (syllogismós), from συλλογίζεσθαι (syllogízesthai), meaning 'to reckon together, to infer, to calculate a conclusion.' The word is composed of σύν (syn, 'together, with') and λογίζεσθαι (logízesthai, 'to reason, to calculate, to reckon'), from λόγος (logos, 'word, reason'). The root sense is 'gathering reasoning together' — the syllogism is what you get when you bring two propositions into relation and draw out what they jointly imply. Aristotle introduced the syllogism in his Prior Analytics as the basic unit of deductive logic: a form of argument consisting of a major premise (a general claim), a minor premise (a specific claim that connects to the major), and a conclusion that follows necessarily from both. The canonical example — 'All men are mortal; Socrates is a man; therefore Socrates is mortal' — was provided not by Aristotle himself but by later commentators, though it perfectly captures the structure he formalized.

Aristotle's achievement in the Prior Analytics was to identify the syllogism as the universal form of deductive inference — not just an example of good reasoning but the skeleton that underlies all valid deductive argument. He catalogued the valid forms of syllogism (the 'figures' and 'moods') and the invalid forms, creating the first systematic formal logic in Western intellectual history. Medieval logicians took Aristotle's syllogistic and elaborated it into a highly technical discipline, assigning Latin names to the valid syllogistic forms (Barbara, Celarent, Darii, Ferio, and so on) — the names were mnemonic devices encoding the form's structural properties in vowel patterns. The scholastic curriculum made mastery of the syllogism central to philosophical education; to reason was to syllogize, and the schoolmen's disputations were essentially public performances of syllogistic form.

Francis Bacon's New Organon (1620) — whose title deliberately echoed Aristotle's logical works (collectively called the Organon, 'the tool') — mounted the most influential early modern attack on the syllogism. Bacon argued that the syllogism was useless for natural philosophy: it could only demonstrate what was already implicit in its premises, and its premises could not be more certain than the observations from which they derived. For a method of inquiry into nature, the syllogism was circular — it could not generate new knowledge about the world, only make explicit what was already assumed. Bacon's alternative was induction from particular observations — the empirical method that would become the touchstone of modern science. This critique did not destroy the syllogism but relocated it: it remained the tool of formal demonstration while induction took over as the method of discovery.

Modern symbolic logic, developed by Frege, Russell, and others from the late nineteenth century onward, replaced the syllogism with a more powerful formal apparatus — predicate logic, which can handle forms of argument that classical syllogistic cannot capture. The syllogism's 'All S are P' structure handles a restricted range of claims; first-order predicate logic can express relations, quantified statements, and complex conditionals that exhaust the syllogistic system's resources. Yet the syllogism survives as a pedagogical tool and as a cultural reference — the word names a form of logical tightness, a chain of reasoning in which the conclusion cannot be denied without denying the premises. 'Your syllogism is flawed' means 'your reasoning does not hold together,' and the accusation is understood even by those who could not name a single syllogistic figure.