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Wellsprings
epistemology

The Syllogism

συλλογισμός

Aristotle's engine of valid reasoning: from two granted premises, a conclusion follows of necessity — the first formal logic in history.

The syllogism is a form of logical argument developed by Aristotle in which two premises necessarily lead to a conclusion. The structure typically involves a major premise, a minor premise, and a derived conclusion—for instance, "All men are mortal; Socrates is a man; therefore Socrates is mortal." Aristotle recognized that syllogisms could be immediate, requiring no intermediate proof, or require reduction to simpler forms. This method became foundational to formal logic because it provided a systematic way to test whether reasoning was valid or flawed.

Aristotle and his followers emphasized that studying syllogisms was essential for understanding valid demonstration and forming sound judgments. They distinguished true syllogisms, which drew conclusions from true premises, from false ones, which either contained errors in the premises or were inconclusive in their reasoning. This framework allowed thinkers to identify valid categorical arguments separately from hypothetical ones, giving them tools to catch logical mistakes in their own thinking and in the arguments of others.

Where this idea shows up

28 Greek sources·2 Jewish-canon citations

Where to read it