What do ad hominems, appeals to authority, red herrings and the straw man argument have in common? Each of these is an example of the Fallacy of Relevance.

Fallacies of Relevance are logical fallacies in which a key part of the argument is actually irrelevant to its conclusion. People often find these fallacies hard to detect.  Understanding how to construct and take apart an argument can help you avoid falling for such fallacies.

Claims Lead to Conclusions

When building a strong argument, you want to use claims that lead logically to your conclusion. For example:

“Loyalty and companionship are the best reasons to have a pet. Because dogs are the best companions and the most loyal animals, they are the best pets.”

You may choose to disagree with the claim that loyalty is the top priority for a pet. Or you may argue that cats (or snakes, or birds) are more loyal. But each part of the argument builds towards its conclusion: that because dogs are the most loyal companions, they are the best pets.

Ad Hominem

The problem begins when claims that are not relevant to the conclusion enter the equation. One common form of this is an ad hominem attack. In the ad hominem fallacy, the person, organization, or entity making the argument is criticized, while the claims and the argument itself go unaddressed. Consider the following exchange:

Russian delegate: “We must intervene to stabilize Iraq.”

American delegate: “Russia is only trying to protect its oil interests.”

The second statement may be true—the problem is that it criticizes the entity that made the argument (Russia), but fails to address the argument itself.

If you’re only criticizing who said it, and not what he said, then you’re probably falling prey to the ad hominem fallacy.

Appeal to Authority

Appeal to authority is similar to ad hominem in that the person making the argument, rather than the argument itself, is the focus. However, instead of being criticized, the person or entity making the argument is held up as a figure of authority. For example:

“Dr. Jones said he’s wrong, and Dr. Jones is a very smart doctor.”

Dr. James may indeed be an excellent doctor and a smart man. But that does not mean that he is right about everything. If the argument involves government intervention in Yemen, or public education policy, or even what time the library closes on Tuesdays, he may well be wrong. In order to evaluate that, we would need to examine the argument itself, rather than simply accepting the statement based on the speaker’s authority.

Red Herrings

What do red herrings have to do with logical fallacies? Nothing—and that’s exactly the point.

The red herring fallacy is when an irrelevant claim is inserted into the argument in order to distract the listener from the real point.

Yes, the weather is nice. And the stock market has also risen. And of course the other candidate running has a criminal record. But is any of that relevant to the question at hand? If not, then you’ve found a red herring. (By the way, did you know that there isn’t really a fish called the “Red Herring”?)

Straw Man

Another fallacy related to the red herring is the straw man fallacy. A straw man is an argument that your opponent cleverly replaces for your real argument. It is usually a similar sounding argument, but one that is easier to dispute:

Senator Smith first lays out her plan to cut taxes. Her opponents  then accuse her of trying to bankrupt the government or plotting to cut key government services. Is that true? Not necessarily, but it’s easier to argue that the senator is cutting government funding than to address the finer points of her tax plan.

To avoid the straw man fallacy, just examine each claim carefully to determine if it really follows from the argument. If you understand an argument and its claims well, you can avoid the straw man and the other fallacies of relevance.


Image credit: “Scarecrow in Rosemoor Garden” by Patche99z, used under CC BY-SA 3.0.