Medium
validitysoundnesssyllogisms

Is This Argument Valid or Invalid?

Problem Statement

Premise 1: All birds can fly. Premise 2: Penguins are birds. Conclusion: Therefore, penguins can fly. Is this argument valid or invalid?

Answer

Valid but unsound

Step-by-Step Explanation

  1. 1

    Validity is about logical structure, not truth.

  2. 2

    An argument is valid if: IF the premises were true, the conclusion MUST be true.

  3. 3

    Let's check the structure:

  4. 4

    - All X are Y (All birds can fly)

  5. 5

    - Z is X (Penguins are birds)

  6. 6

    - Therefore, Z is Y (Penguins can fly)

  7. 7

    This structure is valid — it's a proper syllogism.

  8. 8

    However, the argument is UNSOUND because Premise 1 is false (not all birds can fly).

  9. 9

    Key distinction: Valid = correct logical form. Sound = valid AND true premises.

  10. 10

    This argument is valid but unsound.