The Masked-Man Fallacy: Twisting Arguments Through Invalid Substitutions

The Masked-Man Fallacy

 

The masked-man fallacy is a logical fallacy which is committed when someone assumes that if two or more terms refer to the same thing, then those terms can be freely substituted with one another in a situation where that’s not the case.

For example, the masked-man fallacy could occur if someone claims that, given that Peter Parker is Spiderman, and given that the citizens of New York know that Spiderman saved their city, then the citizens of New York know that Peter Parker saved their city.

The masked-man fallacy can play a subtle but important role in debates on various topics, where people fail to distinguish between the state of things in the world and people’s knowledge of the state of things, so it’s important to understand it. As such, in the following article you will learn more about this fallacy, and see how you can account for it in practice.

 

Understanding the masked-man fallacy

To understand the masked-man fallacy, it’s useful to first see a simplified explanation of the difference between an intension and an extension, as it pertains to this topic:

  • An intension can be thought of as a term which is used to refer to a certain thing (or group of things). For example, the term “Red Planet” is an intension which is used to refer to Mars.
  • An extension can be thought of as the underlying thing (or group of things) that a term is referring to. For example, Mars is the extension that the term “Red Planet” referring to.

Accordingly, any given thing (extension) can potentially be referred to using multiple different terms (intensions). For example, the planet Venus (an extension), can be referred to using the names (intensions) the “Morning Star” and the “Evening Star”.

In extensional contexts, where the only thing that matters is the extension, it’s possible to freely substitute the different terms (intensions) that are used to describe it with one another. For instance, consider the following example of an extensional context:

Premise 1: Bruce Wayne is Batman.

Premise 2: Batman saved Gotham.

Conclusion: Bruce Wayne saved Gotham.

In this example, we’re discussing the underlying entity that is responsible for the action in question. As such, since Bruce Wayne is in fact Batman, it is true that if Batman saved Gotham, then we can say that Bruce Wayne saved Gotham.

Conversely, in intensional contexts, the intensions where are used matter, and so it’s not possible to freely substitute the different terms (intensions) that are used to describe a certain object (extension). For instance, consider the following example of an intensional context:

Premise 1: The citizens of Gotham know that Batman saved their city.

Premise 2: Bruce Wayne is Batman.

Conclusion: The citizens of Gotham know that Bruce Wayne saved their city.

In this example, we’re discussing what the citizens of Gotham know about the entity that saved their city. As such, since the citizens of Gotham don’t necessarily know that Bruce Wayne is Batman, it’s false to say that just because they know that Batman saved their city, then they also know that Bruce Wayne saved their city.

Essentially, even though Bruce Wayne and Batman are both represented by the same person, the fact that people know something about one of them doesn’t mean that they know the same thing about the other.

Based on this, we can say that people commit the masked-man fallacy when they substitute the different intensions (terms) which are used to refer to the same extension (thing), in an intensional object, where doing so is impermissible from a logical perspective. As such, the masked-man fallacy is a formal fallacy, meaning that its reasoning is rendered invalid by a flaw in its logical structure.

Note 1: a related concept is the identity of indiscernibles (also referred to as Leibniz’s law), which denotes that if two entities share the exact same properties, then they are identical. However, what people know or think or say about an entity is not considered a property of that entity, so it’s not always possible to freely substitute these two entities, even if they’re identical. For example, though Bruce Wayne and Batman are considered to be identical, because they share the same properties, that doesn’t mean that people’s knowledge of them is also identical.

Note 2: the masked-man fallacy is also known by several other names. This includes illicit substitution of identicals, because it involves a fallacious substitution of two (or more) identicals, the epistemic fallacy, because it deals epistemology (the study of knowledge), and the intensional fallacy, because it involves a situation where something that was said in an intensional context is treated as if it was stated in an extensional one (meaning that two or more of its intensions are substituted with one another).

 

Examples of the masked-man fallacy

A classic example of the masked-man fallacy is the following:

Premise 1: I know who my father is.

Premise 2: I don’t know who the masked man is.

Conclusion: the masked man is not my father.

This argument is fallacious, because based on these premises alone, there is no way for me to know that the masked man is not my father.

Specifically, this argument assumes that since I know who my father is and since I don’t know who the masked man is, then it’s impossible for the masked man to be my father, based on the false assumption that, if these two terms were referring to the same person, then what I would know about each of them would necessarily be the same (i.e. that what I know and think about my father is necessarily identical to what I know and think about the masked man).

As we saw so far, the masked-man fallacy is often committed when someone discusses people’s knowledge of something or their propositional attitude toward it, which represents things such as their beliefs, hopes, desires, and fears. However, this fallacy can also occur in other situations, such as when quoting what someone had said. For example:

Premise 1: Alex said that Spiderman is a superhero.

Premise 2: Peter Parker is Spiderman.

Conclusion: Alex said that Peter Parker is a superhero.

In arguments and debates, this fallacy is generally more subtle, and is often used in conjunction with a strawman argument, by stating that their support for a person or an idea based on one aspect, means that they also support a different aspect of that person or idea.

Consider the following theoretical example:

Alex: I support the plan to reduce federal healthcare coverage.

Bob: So you’re saying you support a plan for killing thousands of poor citizens.

Bob is twisting Alex’s stance in order to make it easier to attack, by using an invalid substitution. Specifically, while it is possible that he is indeed correct, and that the plan that Alex is supporting (reducing healthcare coverage) is also a plan with the same outcome that Bob describes (killing thousands), that does not mean that that is what Alex is supporting in his mind.

This distinction is crucial: what people know about something is distinct from the properties of that object. Even if this plan has the same outcome that Bob predicts, it’s incorrect to assume that Alex supports this aspect of the plan. If Bob wants to avoid using this fallacy, he can make a similar but modified argument against Alex’s stance:

Alex: I support the plan to reduce federal healthcare coverage.

Bob: The problem is that this plan will lead to the deaths of thousands of poor citizens.

Here, Bob’s argument against the plan itself is similar, but he doesn’t use fallacious reasoning to suggest that Alex directly supports the plan to kill thousands of people. Instead, he argues directly against the plan that Alex supports, without assuming that Alex supports the aspects of the plan that Bob finds problematic.

 

How to counter the masked-man fallacy

The initial strategy for countering this sort of argument is pointing out the flaw in your opponent’s logic. You do this by showing why your opponent’s reasoning is fallacious, and that just because you support X, does not mean that you also support Y.

However, while doing this is valid from a logical perspective, the problem is that it doesn’t help you argue against whatever point your opponent is trying to make against your stance. Furthermore, if you focus too much on the gap in their reasoning, there is the risk that you will appear to implicitly agree with their overall point, which is whatever negative thing they are saying about your stance.

Therefore, you need to make sure that after briefly highlighting the gap in your opponent’s logic, you move on to defending your main stance. For example:

Alex: I support the plan to reduce federal healthcare coverage.

Bob: So you’re saying you support a plan for killing thousands of poor citizens.

Alex: I am definitely not saying that I support such a plan. When did you hear me say that?

Bob: Well, you might not think that, but this will be the outcome of the plan to reduce federal healthcare coverage.

Alex: I disagree with what you’re saying. Recent statistics show…

Here, Alex first points out the flaw in Bob’s reasoning, while simultaneously putting him on the defensive. Then, after Bob is forced to adjust his original, fallacious argument, Alex moves on to argue against the main attack on his stance.

 

Avoiding unintentional use of the masked-man fallacy

You might be using the masked-man fallacy yourself when attacking your opponent’s arguments. This happens whenever you substitute one aspect of their stance for a different aspect of that stance that is often more difficult for them to defend, as we saw above.

The difference between doing this and using a logically-sound argument is that here, you are essentially attacking your opponent’s supposed beliefs, instead of attacking the stance for which they express support.

The problem with using this type of arguments, beyond the inherent issue with relying on logically fallacious reasoning, is that by making your attack more personal, you will usually put the person you are arguing with in a defensive mode, where they automatically reject your argument. This can cause them to support their original stance more strongly, even if you manage to make a good point overall.

Overall, you can avoid using this fallacy yourself by being critical of your reasoning process. Specifically, you should ensure that you don’t make any unverified assumptions about people’s knowledge of the world, which could lead you to rely on invalid substitutions when building your arguments.

 

Summary and conclusions

  • The masked-man fallacy is a logical fallacy which is committed when someone assumes that if two or more terms refer to the same thing, then those terms can be freely substituted with one another in a situation where that’s not the case.
  • For example, the masked-man fallacy could occur if someone claims that, given that Peter Parker is Spiderman, and given that the citizens of New York know that Spiderman saved their city, then the citizens of New York know that Peter Parker saved their city.
  • In everyday arguments, this technique is used when people assume that because someone supports one aspect of an idea (e.g. reducing healthcare coverage), then it means that they also support other aspects of that idea (e.g. killing poor people). Even though both aspects may be true, it is incorrect to assume that if someone supports one of them, then they also know about and support the other aspects of that idea.
  • You can counter this fallacy by briefly pointing out the flaw in your opponent’s reasoning and putting them on the defensive, before moving on to attack the main point in their argument.
  • Remember that you might also be using this fallacy yourself, in cases where you make unverified assumptions about your opponent’s knowledge, and attack their supposed beliefs instead of addressing the actual stance that they support. Doing this generally lead to more personal arguments, which could make your opponent less willing to listen to what you have to say.