Ad hominem fallacy

This fallacy is committed when a person's argument is rejected because of an irrelevant fact or opinion about the person presenting the argument, rather than the argument itself.

Examples:

• A man may have perfectly valid views on abortion, but those views may be rejected by a woman simply because he is "a man";
• A smoker giving advice about not smoking could have their argument dismissed because they indulge in the habit.

The character or position of a person does not have anything to do with the quality of their argument. A good debater needs to be aware of the ad hominem fallacy if he or she is to engage in meaningful debate.

Ad hominem (abusive) - the personal insult.

Ad hominem "attacks" are frequently encountered in debates, often ending up as an exchange of personal insults. Once disagreement occurs, it is very common to see people calling each other: stupid; ignorant; a liar; foolish; a religious nut; an atheist; a dupe; etcetera. Obviously this is not debating: this self-defeating form of abuse should be avoided during a debate.

The abusive ad hominem is often used by people who cannot defend their argument or answer a pertinent question.

Examples:

• You don't believe that Reiki energy is real. That's your prerogative but some of us have open-minds you know!
• Multi Level Marketing works. Don't listen to narrow-minded people who don't have a clue what they're talking about.

The abusive ad hominem is simply a case of: Don’t like the message? Then shoot the messenger.