Two Wrongs Make a Right

When you defend your wrong action as being right because someone previously has acted wrongly, you commit the fallacy called "two wrongs make a right." This is a kind of ad hominem fallacy.

Example:

Oops, no paper this morning. Somebody in our apartment building probably stole my newspaper. So, that makes it OK for me to steal one from my neighbor's doormat while nobody else is out here in the hallway.

Tu Quoque

The fallacy of tu quoque is committed if we conclude that someone's argument not to perform some act must be faulty because the arguer himself or herself has performed it. Similarly, when we point out that the arguer doesn't practice what he preaches, we may be therefore suppose that there must be an error in the preaching, but we are reasoning fallaciously and creating a tu quoque. This is a kind of ad hominem fallacy.

Example:

You say I shouldn't become an alcoholic because it will hurt me and my family, yet you yourself are an alcoholic, so your argument can't be worth listening to.

Discovering that a speaker is a hypocrite is a reason to be suspicious of the speaker's reasoning, but it is not a sufficient reason to discount it.

Smear Tactic

A smear tactic is an unfair characterization either of the opponent or the opponent's position or argument. Smearing the opponent causes an ad hominem fallacy. Smearing the opponent's argument causes a straw man fallacy.

Refutation by Caricature

See Ad Hominem.

Poisoning the Well

Poisoning the well is a preemptive attack on a person in order to discredit their testimony or argument in advance of their giving it. A person who thereby becomes unreceptive to the testimony reasons fallaciously and has become a victim of the poisoner. This is a kind of ad hominem.

Example:

[Prosecuting attorney in court] When is the defense attorney planning to call that twice-convicted child molester, David Barnington, to the stand? OK, I'll rephrase that. When is the defense attorney planning to call David Barnington to the stand?

Name Calling

See Ad Hominem.

Guilt by Association

Guilt by association is a version of the ad hominem fallacy in which a person is said to be guilty of error because of the group he or she associates with.

Example:

Secretary of State Dean Acheson is soft on communism as you can see by the fuzzy-headed liberals who come to his White House cocktail parties and the bleeding hearts of his Democratic Party who call for "moderation and constraint" against Soviet terror.

Has any evidence been presented here that Acheson's actions are inappropriate in regards to communism? This sort of reasoning is an example of McCarthyism, the technique of smearing liberal Democrats that was so effectively used by the late Senator Joe McCarthy in the early 1950s. In fact, Acheson was strongly anti-communist and the architect of President Truman's firm policy of containing Soviet power.

Genetic

A critic commits the genetic fallacy if the critic attempts to discredit or support a claim or an argument because of its origin (genesis) when such an appeal to origins is irrelevant.

Example:

Whatever your reasons are for buying that DVD they've got to be ridiculous. You said yourself that you got the idea for buying it from last night's fortune cookie. Cookies can't think!

Fortune cookies are not reliable sources of information about what DVD to buy, but the reasons the person is willing to give are likely to be quite relevant and should be listened to. The speaker is committing the genetic fallacy by paying too much attention to the genesis of the idea rather than to the reasons offered for it. An ad hominem fallacy is one kind of genetic fallacy, but the genetic fallacy in our passage isn't an ad hominem. If I learn that your plan for building the shopping center next to the Johnson estate originated with Johnson himself, who is likely to profit from the deal, then my pointing out to the planning commission the origin of the deal would be relevant in their assessing your plan. Because not all appeals to origins are irrelevant, it sometimes can be difficult to decide if the fallacy has been committed. For example, if Sigmund Freud shows that the genesis of a person's belief in God is their desire for a strong father figure, then does it follow that their belief in God is misplaced, or does this reasoning commit the genetic fallacy?

Circumstantial Ad Hominem

See Ad Hominem.

Against the Person

See Ad Hominem.

Ad Hominem

You commit this fallacy if you make an irrelevant attack on the arguer and suggest that this attack undermines the argument itself. It is a form of the Genetic Fallacy.

Example:

What she says about Johannes Kepler's astronomy of the 1600's must be just so much garbage. Do you realize she's only fourteen years old?

This attack may undermine the arguer's credibility as a scientific authority, but it does not undermine her reasoning. That reasoning should stand or fall on the scientific evidence, not on the arguer's age or anything else about her personally.

If the fallacious reasoner points out irrelevant circumstances that the reasoner is in, the fallacy is a circumstantial ad hominem. Tu Quoque and Two Wrongs Make a Right are other types of the ad hominem fallacy.

The major difficulty with labeling a piece of reasoning as an ad hominem fallacy is deciding whether the personal attack is relevant. For example, attacks on a person for their actually immoral sexual conduct are irrelevant to the quality of their mathematical reasoning, but they are relevant to arguments promoting the person for a leadership position in the church. Unfortunately, many attacks are not so easy to classify, such as an attack pointing out that the candidate for church leadership, while in the tenth grade, intentionally tripped a fellow student and broke his collar bone.

Abusive Ad Hominem

See Ad Hominem.