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 names or descriptions refer to the same thing, then they 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 intensionality and extensionality, 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, which involves distorting an opponent’s argument, in order to make it easier to attack. One way to do this is by stating that someone’s support for one aspect of a person or an idea, means that they also support a different aspect of them, even if the person in question was unaware of that additional aspect.

Consider the following theoretical example:

Alex: I support the plan to reduce the federal education budget.

Bob: So you’re saying that you support the plan to fire thousands of teachers.

In this example, Bob is twisting Alex’s stance in order to make it easier to attack, by using an invalid substitution. Specifically, while it’s possible that Bob is indeed correct, and that the plan that Alex is supporting (reducing the education budget) will have the outcome that Bob describes (firing thousands of teachers) in practice, that doesn’t mean that this is what Alex is supporting, in his mind.

This distinction is crucial since, as we saw above, what people know about something and how they feel toward it is distinct from its actual properties. As such, even if the plan in question will have the same outcome that Bob predicts, it’s incorrect to assume that Alex knows that he’s supporting this. Accordingly, if Bob wants to avoid using the masked-man and strawman fallacies in this case, he can make a similar but modified argument against Alex’s stance, as in the following example:

Alex: I support the plan to reduce the federal education budget.

Bob: The problem is that this plan will lead to the firing of thousands of teachers.

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 fire thousands of teachers. 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 respond to the masked-man fallacy

In order to counter the use of the masked-man fallacy, the main thing that you can do is point out and explain the flaw in the logic of the person who is using it. For example, if someone is substituting two terms that refer to the same entity in a situation where the distinction between those terms matters, you can point out this issue, and explain why the argument is therefore fallacious.

However, while this approach is, in theory, the valid way to deal with a gap in someone’s logic, in practice doing this won’t always help you change an opponent’s mind when it comes to an actual discussion, for several reasons.

First, understanding this fallacy can sometimes be difficult for people, which could cause them to simply reject your explanation. Second, focusing on the logical issue in someone’s reasoning can often mean that you neglect to address the main point that the other person is trying to make. Furthermore, in cases where people use this fallacy against you in a debate, if you focus too much on the gap in your opponent’s reasoning, there is the risk that you will appear to implicitly agree with their overall point.

Therefore, when responding to someone’s use of the masked-man fallacy, you generally want to use a simple and intuitive explanation of the issue in their reasoning, that they will be able to easily understand, or to use some other approach, such as asking your opponent to properly support their statement. Then, you should move on, and address the main point that the other person is trying to make. For example:

Alex: I support the plan to reduce the federal education budget.

Bob: So you’re saying that you support the plan to fire thousands of teachers.

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 education coverage.

Alex: I disagree with what you’re saying. What the plan is actually proposing is…

Here, Alex first calls out the flaw in Bob’s reasoning, while simultaneously asking him to justify his statement. Then, after Bob adjusts his original, fallacious argument, Alex moves on to argue against the main attack against his stance.

 

Avoid unintentional use of the masked-man fallacy

It’s important to keep in mind that you might be using the masked-man fallacy yourself, in various situations. As we saw above, this happens whenever you substitute different names or descriptions with one another, because they refer to the same thing, in a situation where it’s inappropriate to do so.

Accordingly, you should make sure to examine your reasoning process properly, to ensure that you’re not using this fallacy. In particular, you should be wary when discussing what people know, how they feel, or what they say, since discussions relating to this are especially likely to lead to the use of the masked-man fallacy.

Most notably, when addressing other people’s beliefs, you should make sure to always address their beliefs as they were originally stated, rather than substituting those beliefs with something that you feel is an equivalent. For example, if someone says that they support X, you should not say that they support Y, even if these two terms are different names that refer to the same underlying thing. Rather, you should acknowledge that their support is for X, and then explain why that means that they also support Y.

Doing this is beneficial because it ensures that you avoid using a fallacious reasoning and argumentation process, and because it will likely make the other person more willing to listen to what you want to say.

 

Summary and conclusions

  • The masked-man fallacy is a logical fallacy which is committed when someone assumes that if two or more names or descriptions refer to the same thing, then they 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 situations, people often use this fallacy when they assume that if someone supports one aspect of an idea, then it means that they also support other aspects of that idea, that they’re not necessarily aware of.
  • To respond to the use of this fallacy, you generally want to use a simple explanation of the logical issue involved, and potentially also ask the person using the fallacy to support their argument, before moving on to address the main point that they’re trying to make.
  • To avoid using this fallacy yourself, you should make sure to examine your reasoning process, particularly when discussing what people know, how they feel, or what they say, and you should address people’s beliefs as they were originally stated, rather than substituting their belief with something that you feel is an equivalent.