Invalid Argument/Examples/Rockefeller was Not Famous

Example of Invalid Argument

The following is an valid argument with true premises and a false conclusion:

If Nelson Rockefeller was President then he was famous.

Nelson Rockefeller was not President.

Therefore Nelson Rockefeller was not famous.

Proof

This is an example of Denying the Antecedent.

It is true that being President makes you famous, and it is also true that Nelson Rockefeller was not President.

However, it is not true that not being President makes you not famous.

$\blacksquare$

Sources

• 1973: Irving M. Copi: Symbolic Logic (4th ed.) ... (previous) ... (next): $1$ Introduction: Logic and Language: $1.3$: Truth and Validity