Lesson · 4 min Steady
Valid Is Not the Same as True
In one line A valid argument guarantees its conclusion only when its premises are true, so check the form and the facts.
An argument is valid when its conclusion must be true if its premises are true. Validity is about the shape, not the facts. “All fish can fly. Salmon are fish. So salmon can fly” is valid: grant the premises and the conclusion follows. It is still false, because the first premise is false.
An argument is sound when it is valid and its premises are true. Only a sound argument guarantees its conclusion. So ask two questions of any argument: does it follow, and are the starting points true?
This gives you a fair move when a valid argument reaches a conclusion you reject. You cannot simply deny the conclusion. You have to say which premise is false, because if they were all true, the conclusion would be too.
The step counter
Kiri’s fitness app tells her: “Anyone who walks 10,000 steps a day is healthy. You walked 10,000 steps every day this month. So you are healthy.”
The argument is valid, but its first premise claims too much: steps alone do not rule out high blood pressure. Kiri keeps walking and books the checkup she had been putting off.
Try this today Find one argument today whose conclusion you doubt, and name the premise you think is false.
Cite or share this lesson
A plain reference you can paste into notes or an essay:
Quest2Reason. “Valid Is Not the Same as True.” https://quest2reason.com/learn/lesson/valid-is-not-true. Accessed 14 November 2026.
Sources
- “Validity and Soundness,” Internet Encyclopedia of Philosophy — Valid and sound arguments defined, with examples of valid arguments that have false premises.
- “Logical Consequence,” Stanford Encyclopedia of Philosophy — Why validity depends on form, not on whether the premises happen to be true.