Ad Hominem Fallacies

Chapter Ten
Philosophy 404
Summer 1999

At times during a discourse episode where arguments are being advanced, a participant will adduce considerations about the person advancing the argument (e.g., their character, habits, appearance, etc.). This argumentative move is known as the ad hominem. This move is dangerous because it often introduces considerations that are irrelevant to the argument advanced by the speaker, and so is at best misleading and at worst disruptive. However, as with many of the argument forms we considered in Chapter 10, this one can be used to positive effect as well. Here is a classification of ad hominem moves:

  1. Ad Hominem Attack: if in response to a contribution made by speaker A to an argument, speaker B questions A's character, motives, or right to speak, then B makes an ad hominem attack. (Note that the attack is not directed at the argument A advances, but only surrounding conditions.) These can be justified or unjustified; whether these are justified or not depends on whether they are relevant to the argument advanced.

    1. If you question a person's motives and it turns out that they are in fact driven to speak by questionable motives, your attack is justified.

    2. If they are driven by other, more selfless motives, then your attack is not justified. If you attack their right to speak and they have none, you are justified; if they do have the right, your attack is unjustified.

  2. Ad Hominem Argument: if B calls into question A's person as a way of attacking the argument that A is advancing, then B makes an ad hominem argument. These can also be justified or unjustified.

    1. If B's argument raises questions about the soundness of A's arguments, then the ad hominem argument is justified. For example, if A is noted for stretching the truth and B points this out, that would be relevant given that we would wish to evaluate A's claims for truth.

    2. If B advances an ad hominem argument that does not give us any reason to question the truth of A's claims or the soundness of A's argument, the B's argument will be unjustified and will be what we call an ad hominem fallacy. Many ad hominem arguments are fallacious, primarily because the argument advanced does not usually depend for its legitimacy on the person advancing it.