Logical Reasoning
Deductive reasoning
Reasoning from a general rule to a specific case.
| English | Deductive reasoning |
|---|---|
| Bahasa Melayu | Penaakulan deduktif |
| 中文 | 演绎推理 |
How it is used
Using deductive reasoning: the general rule is "the angles in any triangle add up to 180°". A triangle has angles 90° and 55°, so the third angle must be 180° − 90° − 55° = 35°.
The specific answer follows from the general rule.
Where it shows up in SPM
Deductive reasoning is contrasted with inductive reasoning in Form 4 Logical Reasoning. Paper 1 asks you to classify a piece of reasoning as deductive or inductive.
Paper 2 combines it with the three argument forms to reach and justify a conclusion.
Don't confuse it with
Open the chapter: Logical Reasoning →
Frequently asked questions
How do I recognise deductive reasoning?
Look for a general rule applied to a particular case. If a solution starts from a known formula or property and works down to one specific answer, it is deductive.
Moving from "all", "every" or a fixed rule toward a single case is the clue.
Is deductive reasoning always correct?
A valid deductive argument gives a certain conclusion when its premises are true. If a premise is wrong, the conclusion can still be wrong.
So deduction makes the reasoning valid, but only if the general rule you start from is itself true.