Darty E. Darty
Introduction
The syllogism is often regarded as Aristotle‟s chief accomplishment in logic. This is why
Bertrand Russell says that Aristotle‟s most important work in logic is the doctrine of the
syllogism (Russell, Aristotle‟s Logic 120). In support of this point of view, Peter King and
Stewart Shapiro asserts that “Aristotle was the first thinker to devise a logical system; the
syllogism was his greatest invention in logic” (496). Aristotle defined the syllogism as “a
discourse in which certain things being stated, something other than what is stated follows of
necessity from their being so. I mean by the last phrase that they produce the consequence, and
by this that no further term is required from without in order to make the consequence necessary”
(Aristotle, Prior Analytics 5). Aristotle gave priority to the categorical proposition as the most
fundamental statement (Hurley 6). Hence, a syllogism is a form of reasoning which consists of
three categorical propositions having between them exactly three terms each of which occur
twice in a manner that the first two propositions jointly imply the third proposition. Since logic
deals with arguments and arguments are made up of propositions, it is necessary to begin the
discussion on categorical syllogism with an elucidation of the notion of „class‟ as the defining
quality of categorical propositions.
