Aristotle, the first person we know who wrote down laws of deduction, gives this example of deduction:
- All men are mortal.
- Socrates is a man.
- Therefore, Socrates is a mortal.
The first two statements are called "premises". The last statement is called the "conclusion". The conclusion is taken from the premises. If one of the premises is wrong, the conclusion will also be wrong. Mathematicians use deduction to discover new mathematics.