Obstacles to Good Reasoning 5: Relevance, Straw man, Red Herring, and Moving the Goal Posts


To evaluate an argument there are two notions of relevance we need to pay attention to. The first is contextual relevance. In the context of a debate between two sides, contextual relevance is the degree to which a response or line of argument is relevant to the main issue being debated. An argument can fail to be contextually relevant in two main ways. First, it can attack a misrepresentation of the opponent's view. This is called a straw man argument. A straw man argument isn't contextually relevant to the topic of debate because it doesn't address the opponent's actual arguments since they are a distortion or misrepresentation. A line of argument can also fail to be contextually relevant when it's off topic. Such arguments are red herrings. They draw the debate away from the actual issue. The most frustrating failure of contextual relevance is when an opponent moves the goal posts. We can think of moving the goal posts as a series of red herrings. Any time you address your opponent's concern, they reply "yeah, but what about [new concern]?" This is a common tactic for science denialists and conspiracy theorists.

The second notion of relevance is called internal relevance, or sometimes, premise relevance. Premise relevance concerns the relationship between a particular premise and a conclusion (or a sub-conclusion). It is the measure of how much (if at all) a particular premise makes a conclusion likely to be true. A premise with strong premise relevance strongly increases the likelihood of a conclusion being true. A premise will weak or no relevance doesn't really increase the likelihood of a conclusion being true.

Contextual Relevance:

In the context of a debate, contextual relevance is the degree to which a response or line of argument is relevant to the main issue of debate. Contextual relevance is about whether an entire argument has a logical relationship to the topic that is being debated. Red herring and straw man are two ways that an argument can fail to have contextual relevance. The third way, moving the goal posts, can be thought of as a series of red herrings. Let's look at each in detail.

Red Herring

A red herring is an attempt to move the debate away from the issue that is the topic of an argument. Basically, a red herring is an objection to a position that doesn't address the actual issue being debated. Its premises are irrelevant to the conclusion it seeks to negate/oppose.

Let's look at an example from Plato's Republic:

Socrates: Rebecca Black is such a great singer. Her voice is a combination of Jesus and Fergie.
Glaucon: Whatev, her voice is auto-tuned. If she were singing live you'd hear that she's out of tune. Therefore, she is not a great singer.
Socrates: Why do you hate her? OMG, you're so mean!

The main issue of the debate is whether Rebecca Black is a great singer. Glaucon's argument is that Rebecca Black's voice isn't very good and he provides supporting reasons. Instead of replying to Glaucon's argument by addressing his premises or reasoning, Socrates brings up an issue irrelevant to the argument. In short, Socrates's assertion that Glaucon is mean is not relevant to the main issue, i.e., whether Rebecca Black is a great singer. Glaucon's opinion of Rebecca as a person has no bearing on whether she's a good singer or not—regardless of what day of the week it is.

So, since critical thinking is a method for systematically evaluating arguments, reasons, and premises, here's our method for identifying red herrings.

1. What's the issue of debate?*
2. Is the argument being presented on the same topic?
3. If not, then it is a red herring.

One quick note about how to figure out what the issue is. Usually we can state the main issue of a debate with a sentence beginning with "whether… ." For example, familiar debates we can state as "whether GMOs are safe to eat, whether X was a good President, whether gun control legislation unduly restricts Second Amendment freedoms, etc… ." So, when you are evaluating for contextual relevance try to express the debate in terms of a "whether" statement.

The red herring fallacy has many cousins and sub-species which we'll examine later in the course. Some of them you may have heard of: non-sequitur, ad hominem, and tu quoque. When you use the Latin names you can really impress your friends…yay!

Moving the Goalposts

Moving the goalposts (aka the "Oh Yeah?" Defense) Definition: A topic is under discussion. Person 1 shows why Person 2's argument fails to support their position on the issue. Instead of admitting defeat, person 2 changes the standard of evidence or changes the topic to one that is closely related but not the same as the original one. Basically, when Person 1 shows why person 2's argument fails, Person 2 responds by saying "oh yeah? what about this?"


Person 2: Vaccines are bad because the mercury in vaccines causes autism.
Person 1: There is no mercury in vaccines. All vaccines except the flu vaccine have been mercury-free since 2001. If mercury in vaccines caused autism, we'd expect the autism incident rate to have fallen since 2001 but it hasn't. It has increased. So even if mercury in vaccines of the past did contain mercury, the amount that they contained wasn't enough to cause autism.
Person 2: Oh yeah! Vaccines have formaldehyde! And formaldehyde is bad for you.
Person 1: Everything is bad for you if the dosage is high enough but the amount of formaldehyde in vaccines in insignificant. There is actually more formaldehyde in a single pear than there is in a child's vaccine schedule. Also, our own bodies produce much more formaldehyde in a single day than we ever get in vaccines.
Person 2: Oh yeah! too many too soon…

Dealing with moving goalposts:
Moving the goalposts is extremely common when debating science denialists and conspiracy theorists. Here are a few tricks to avoid getting caught in this endless cycle of frustration. (a) Before engaging in debate ask your opponent to commit to a claim and a reason for why they believe the claim. Then repeat back to them what they said, i.e., "so you think that X because Y, did I get that right?". Once they say "yes", it's on like Shaka Khan. This way, when they try to move the goal posts, you can copy-pasta what they previously committed to.

For example, in the above example of goalpost moving, person 1 should have first asked, (a) what is your claim? and (b) why do you believe it? Person 2 would then have to say that (a) vaccines are bad (b) because the mercury in them causes autism. Now, Person 1 can say, address the mercury claim. If Person 2 now tries to move the goal posts, Person 1 can say "hold on a second, you just told me that you believe vaccines are bad because of the mercury and I just explained that there is no mercury therefore you shouldn't think vaccines aren't bad. So, either mercury wasn't your reason or you should now agree that there's no reason to fear vaccines." Although Person 2 will probably still try to move the goal posts, at least they will have to do so admitting that the mercury isn't a reason to oppose vaccines.

Straw Man

A straw man doesn't address the opposing argument because it misrepresents or distorts and so it fails address the main topic under debate. A straw man argument often contains a grain of truth, but the opposing position is so blown out of proportion it is hardly recognizable. The general purpose of a straw man argument is to present an opponents position in a way that makes it seems ridiculous, weak, and obviously wrong so it's easy to defeat. The problem is that since a straw man isn't the opponent's actual position, it hasn't been defeated (or even genuinely addressed).

A great source for straw man arguments is any heavily biased news source in regards to emotional debates. Sentiments like "Obama's going to take all our gunz" is a straw man argument against proposed gun control legislation. While there may be some truth in that the proposed legislation seeks to ban assault weapons, there is no part of any proposed bill that requires all gun owners to turn in every type of gun they own retroactively. Conversely, proponents of gun-control legislation might make a straw man out of the legislation's opponents by arguing that pro-gun people don't want any restrictions at all on gun ownership and types of ownership. Most gun owners do in fact endorse some restrictions on gun ownership. Straw men arguments might look like this:

Person A: Given the tragic nature of mass shootings, we should consider implementing some sort of background check to make sure people buying guys don't have any known major psychological problems or any records of violent criminal behavior.
Person B: My opponent doesn't think people have the right to own guns. In person A's world, citizen's won't be able to lawfully defend themselves or even go hunting.


Person A: If you deny people the right to self-defense then you are risking increasing the rate home break-ins because a major deterrent will have been removed.
Person B: My opponent thinks we should give children AK-47s for self-protection when their parents aren't home. This is obviously a bad idea.

From the point of view of critical thinking there are a few important points to notice: (a) The straw man gun control arguments on both sides distort the respective opponent's position such that its actual content isn't being addressed, (b) because the opposing argument is distorted it seems ridiculous and easy to refute, and (c) because the actual content isn't being addressed, the topic of the argument gets shifted away from the actual content of a position rendering meaningful dialogue difficult.

Given the above observations we can say that a straw man argument has the following structure:

Person A gives their position or argument; call it argument X.
Person B reformulates (i.e., exaggerates and distorts) Person A's position to make it look ridiculous/implausible (call it argument Y).
Person B then shows why argument Y is a bad argument.
The problem is that Person B hasn't shown that person A's actual argument (X) is faulty.

Here's one more example:

(From the Washington Post)
BLM contends that Bundy owes $1 million in fees, and will also have to pay the round-up expenses. Bundy — who retorts that he only owes $300,000 in fees — says the city folk are only hurting themselves by taking his cows. He told a reporter from the Las Vegas Review Journal that there would be 500,000 fewer hamburgers per year after his cows were towed away; “But nobody is thinking about that. Why would they? They’re all thinking about the desert tortoise. Hey, the tortoise is a fine creature. I like him. I have no problem with him. But taking another man’s cattle? It just doesn’t seem right.”

Hotly debated topics are fertile ground for straw man arguments. For good examples read the comments section for any article on GMOs, nuclear power, natural gas fracking, gun control, health care (in the US), immigration policy, and public policy regarding religion.

Internal/Premise Relevance

Premise relevance measures the degree to which a particular premise makes a conclusion likely to be true. Premise relevance is a matter of degree. Some premises will support conclusions more than others and some premises will offer no support, such as in cases of informal fallacies. For example, suppose I want to prove that (C) a certain animal 'x' is a duck. I give the following premises

P1. The animal waddles.
P2. The animal quacks.
P3. The animal has a stomach.
P4. The animal has a reality TV show and is a primate.
C. The animal is a duck.

Notice that P1 increases the likelihood that (C) the animal is a duck. Same goes for P2. P3 is neutral. And P4 actually decreases the likelihood of the conclusion being true. It increases the probability of another conclusion: that the animal is a cast member of Duck Dynasty. Premises that swing the probability against the main conclusion can be used as premises in a counter-argument.

A note on extended arguments: The argument we just looked at is a simple argument because no premise requires further support. In the case of extended arguments some premises require further support. In these cases, the sub-premises will be relevant to the sub-conclusion they support but not directly relevant to the main conclusion. In your evaluation you should indicate this.

Summary and Key Points for Internal Relevance:
(1) When we evaluate for premise relevance we are looking at whether the information in a premise increases or decreases the likelihood of a conclusion being true.
(2) When we evaluate for relevance we assume the premises are all true—even if they aren't.
(3) When we evaluate for relevance we evaluate each premise individually. It's possible that some premises will be relevant while others might not be.

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