Masked Man

Description

The masked man fallacy (MM) draws a conclusion about identity from a difference in what someone believes or knows under different descriptions.

MM involves drawing unjustified conclusions about what is true based on intentional attitudes such as beliefs and desires. The fallacy gets its name from this example:

1. Joe believes that a masked man robbed the bank.
2. Joe does not believe his father robbed the bank.
3. Therefore, the masked man is not Joe’s father.

The inference is a fallacy because, unbeknown to Joe, his father might have donned a mask and robbed the bank.

Principle of Indiscernibility of Identicals

The principle of the indiscernibility of identicals says that if A is identical with B, every property of A is a property of B. If water is H2O, water and H2O are the same substance. But substituting names or descriptions inside a report of someone’s beliefs can change the report’s truth. If the robber is Joe’s father, Fred, Joe can believe that the masked man robbed the bank without believing that his father did so. The difference concerns Joe’s understanding of the descriptions, not a difference between the people they name.

Opacity of Beliefs

Belief reports are opaque contexts: exchanging descriptions of the same person need not preserve what the person believes. Joe may not realize that ‘the masked man’ and ‘my father’ refer to Fred. Also, not believing that his father robbed the bank does not necessarily mean believing that his father did not rob it; Joe may simply have no view on the question.

Non-fallacious Redescription

While the case of the masked man seems to be a clear fallacy, the case can be redescribed to offer a non‐fallacious inference. Imagine Joe justifiably believes many things about the masked man (he is over 6 feet tall, speaks German, and is right‐handed) and that he justifiably believes these things are not true of his father (he is 4 feet tall, cannot speak German, and lacks a right hand). From such a vantage point, Joe would justifiably believe that the masked man is not his father. Another caveat is in order about Joe’s being able to draw a conclusion about the world from his different beliefs: Joe is justified in believing that the properties of being a masked man and being his (or a) father are distinct.

Philosophical Application

A controversial philosophical argument that involves the MM is in the philosophy of mind. Some philosophers have maintained that there are some things true of the mental (e.g., we have immediate, experiential access to our mental states) that are not true of the physical (e.g., we do not have immediate, experiential access to our neurological states). In reply, it has been argued that we cannot, given this apparent disparity, conclude that the mental is distinct from the physical because, unknown to us, it might turn out that the mental is the physical or, more particularly, the mental is brain activity. This objection, however, is not as clear as the case of the masked man. First, the data would seem to support what is often called property dualism, the thesis that the property of being immediately, experientially accessible to a person is distinct from the property of not being immediately, experientially accessible to a person. Second, the data might still be problematic to an identity theory (identifying the mental and physical) and not easily disposed of based on a masked man objection insofar as one has reason to believe that everything true of the physical would not include the mental, for example, one has reason to believe that one can exhaustively and sufficiently describe (in the language of physics, chemistry, biology) all the facts about the physical world without describing (or knowing about) the mental. Based on the indiscernibility of identicals, this data would provide some reason for thinking that the physical is not the same as the mental.

Kierkegaard and Epistemic Humility

The contrast with an omniscient, God’s‐eye view associated here with Kierkegaard makes the limitation clear. For a God that knows everything (God knows of all truths that they are true and of all falsehoods that they are false), everything would be transparent. But, for us, our knowledge is typically imperfect and we need to be careful about when to draw conclusions in light of our limitations.

This fallacy may be avoided to the extent that we cultivate what many refer to today as epistemic humility. We need to be aware of when our beliefs reflect our proper access to some state of affairs and when our beliefs are mediated through different lenses. For example, you may know that you see Boris entering a hotel in Istanbul and not know that you are seeing the tallest Russian spy entering a hotel in Istanbul. Only infer that Boris is not the tallest Russian spy if you know a great deal more, for example, you happen to know that while Boris is entering that hotel, the reason you do not know that the tallest Russian spy is entering the hotel is because you actually have reliable information that she is under surveillance at the Russian embassy. We need to know our limitations when we make inferences based on partial information.