Reductio ad absurdum
Reductio ad absurdum is a Latin phrase which means reduction to the impossible. It is a trope used in arguments or debate. It is an informal fallacy. The phrase describes a kind of indirect proof. It is a kind of proof by contradiction.[1] The reasoning is flawed because it distorts issues. The actual problem is eclipsed by the process of re-focusing on something else.
The ridiculous or "absurdum" conclusion of a reductio ad absurdum argument can have many forms. For example,
- Rocks have weight, otherwise we would see them floating in the air.
This reasoning tries to persuade by making up an impossibility.
- Society must have laws, otherwise there would be chaos.
This reasoning tries to persuade by making up a possibility that is unacceptable or unworkable.
Contents |
History [change]
The phrase can be traced back to the Greek η εις άτοπον απαγωγή (hê eis átopon apagogê). This phrase means "reduction to the impossible". It was often used by Aristotle.[2]
Method [change]
Reduction ad absurdum can be a tool of discovery.[3]
The method of proving something works by first assuming something about it. Then other things are deduced from that. If there is a contradiction, it shows that the first something cannot be correct. For example,
Related pages [change]
References [change]
- ↑ 1.0 1.1 Weston, Anthony. (2009). A Rulebook for Arguments, pp. 43-44.
- ↑ Heath, Thomas Little. (1908). The Thirteen Books of Euclid's Elements, Vol. 1, p. 136.
- ↑ Polya, Goerge. (2008). How to Solve It: A New Aspect of Mathematical Method, p. 169.
