Ad Hominem (Direct Fallacy)
A direct ad hominem fallacy uses an irrelevant personal attack to dismiss an argument. The key question is whether the criticism bears on the evidence or reasoning at issue.
THE IDEA
Ad Hominem (Direct Fallacy)
An ad hominem argument attacks the character, motives, or circumstances of the person making an argument, instead of addressing the argument itself. This fallacy is committed when the personal attack is irrelevant to the logical or evidentiary support for the argument.
Example 1: General Petraeus
Respondent: General Petraeus’s argument for aggressively pursuing ISIS can’t be trusted because it is likely that he gave classified documents to a reporter with whom he was having an extramarital affair.
Following our critical questions, we should first inquire whether the allegations against Petraeus are well founded. If they are not, the ad hominem argument does not get off the ground. If they are true, we need to ask whether the allegations are relevant to the argument.
The second critical question concerns relevance. Is Petraeus’s character relevant to whether his premises support his conclusion? In deductive arguments, validity depends on form, not character. In inductive arguments, strength depends on content, not character. So the allegations are irrelevant to the logical support.
The third critical question clarifies the respondent’s conclusion: is she claiming (a) the allegations refute Petraeus’s position, or (b) they question his character sufficiently to require further evidence? Even if the allegations do not refute the argument, they might question his integrity or motives. However, in this case the allegations about an affair and leaking classified documents do not speak to his competence or motives regarding ISIS. Thus, they fail to be relevant for questioning or refuting the argument, and the respondent commits the fallacy of ad hominem: direct.
It is possible for an ad hominem argument to be fallacious when read as refuting the position but not fallacious when read as calling it into question.
When to use it
Evaluating arguments in political debates where personal attacks are common but often irrelevant.
Analyzing legal arguments where a lawyer attacks the character of a witness instead of their testimony.
Assessing online discussions where participants dismiss an argument by insulting the person making it.
Teaching critical thinking to identify fallacious reasoning in media and everyday conversations.
FROM THEORY TO EVERYDAY LIFE
In practice
General Petraeus Example
A respondent cites allegations about General Petraeus’s affair and disclosure of classified documents to dismiss his argument about pursuing ISIS. Those allegations do not establish that the premises fail to support the conclusion. A separate challenge to his credibility would need to explain its relevance.
A MOMENT TO REFLECT
Put it to work.
How can you determine whether an ad hominem attack is relevant to the argument it targets?
In what situations might an ad hominem argument be considered non-fallacious, such as when questioning a person's credibility in a relevant domain?
Think of a recent debate where an ad hominem was used. Was it fallacious? Why or why not?
CONTINUE THE CONVERSATION
Source texts
- Bad Arguments 100 of the Most Important Fallacies in Western Philosophy (Steven Barbone, Michael Bruce)