Deduction

Deduction, or deductive reasoning, is a type of Logical Reasoning where the conclusion must follow from the premises. If the argument is valid and all its premises are true, the conclusion is guaranteed to be true.

• Rule: All men are mortal.
• Observation: Socrates is a man.
• Conclusion: Socrates is mortal.

Compare this with Induction, which generalises from examples, and Abduction, which finds a plausible explanation. Neither guarantees a true conclusion.