Philosophy
What is A syllogism?
A syllogism is a form of logical reasoning that draws a conclusion from two premises. The classic example: all men are mortal; Socrates is a man; therefore Socrates is mortal. It's a fundamental building block of deductive logic.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains a syllogism.
Key things to understand
- 1It has two premises and a conclusion that follows from them.
- 2If the premises are true and the form valid, the conclusion must be true.
- 3Classic example: All men are mortal; Socrates is a man; so Socrates is mortal.
- 4A valid form can still give a false conclusion if a premise is false.
- 5Aristotle formalized syllogisms over 2,000 years ago.
Frequently asked questions
- What is an example of a syllogism?
- All birds have feathers; a robin is a bird; therefore a robin has feathers — a conclusion forced by the two premises.
- Can a syllogism be valid but wrong?
- Yes — if a premise is false, the logic can be valid yet the conclusion untrue; valid form guarantees truth only when the premises are true.
- Who invented the syllogism?
- Aristotle, who systematized this form of deductive reasoning in ancient Greece.