From Logic

A syllogism, is a deductive argument containing two premises and a conclusion. Aristotle defines syllogism as: "a discourse in which, certain things having been supposed, something different from the things supposed results of necessity because these things are so." (24b18–20) Despite this very general definition, however, he limits himself first to categorical syllogisms (and later to modal syllogisms). The syllogism is at the core of deductive reasoning, where facts are determined by combining existing statements, in contrast to inductive reasoning where facts are determined by experimenting on the world.

Note: If an argument has a major premise, a minor premise, and a conclusion and draws an absolute conclusion, then it is a syllogism. But if the argument has all three parts and comes to a probable conclusion, it is an enthymeme, not a syllogism.


  • Aristotle, Prior Analytics
  • Hurely, P. J. (2000) A Concise Introduction to Logic - 7th Edition
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