Syllogism is a form of logical argument which uses destructive reasoning to come to a conclusion on the basis of two propositions which are asserted or presumed to be true. It was first proposed by Aristotle in his book Prior Analytics in the year 350 BCE.
Here is an example of a syllogism:
All men are mortal.
Aristotle is a man.
Hence Aristotle is mortal.
The basic structure of a syllogism consisted of three parts – a major premise, minor premise and an inference or conclusion. Each part has a categorical proposition, which in turn contains two categorical terms – universal propositions (“All A are B” & “No A are B”) and particular propositions (“Some A are B” & “Some A are not B”).
Aristotle’s syllogism dominated Western philosophical thought for several centuries. It’s major flaw, however, was that it focused more on drawing valid conclusions from axioms rather than verifying the assumptions made.
This prospect of syllogism attracted a lot of controversy around it. In the 17th century, philosopher Francis Bacon put forth that experimental verification of axioms are paramount in drawing conclusions in nature and syllogism cannot be seen as the best way to do so. However, the biggest contributor to syllogism’s eventual fall as an idea was brought about by Gottlob Frege in his book Begriffsschrift in 1879 where he used variables and quantifiers to represent thought. The major evidence that put in the nail in the coffin for syllogism was this particular argument:
If “some cats are black things” and “some black things are televisions”, according to syllogism’s conclusion, “some cats are televisions” which is an illogical argument and goes against what it was created for.
However, it is still used as a general audience introduction into logic as a concept as it is easy to understand for all.
To learn more about syllogisms, click here.