Ad hominem

Ad hominem fallacies involve attacking the person rather than the argument, e.g., by casting aspersions on that person's character, or associating the person with a distasteful ideology.

This is a logical fallacy because the fact that a person is repugnant does not mean that they are wrong.

Examples

• Elizabeth claims that John murdered Sally
• Elizabeth is a convicted drug user
• Therefore Elizabeth's claims aren't trustworthy

• Bob says that the sky is blue.
• Bob is a communist, and cannot be trusted.
• Therefore, the sky is not blue.