The argument from incredulity is a logical fallacy that occurs when someone concludes that since they can’t believe something is true, then it must be false, and vice versa. For example, someone using the argument from incredulity might claim that since they don’t see how a certain scientific theory could be true, then it must be false.
People often use arguments from incredulity in an attempt to discredit valid theories that they disagree with, and in order to support various unfounded or pseudoscientific theories, so it’s important to understand this fallacy. As such, in the following article you will learn more about the argument from incredulity, and see what you can do in order to respond to its use.
Explanation of the argument from incredulity
Arguments from incredulity generally have one of two basic forms:
“I can’t imagine how X could be true; therefore, X must be false.”
“I can’t imagine how X could be false; therefore, X must be true.”
This way of thinking is fallacious, since someone’s inability to believe that something could be true, does not mean that it must be false, just as someone’s inability to believe that something could be false, does not mean that it must be true.
From a formal perspective, the basic structure of an argument from incredulity can be described as follows:
Premise 1: I can’t explain or imagine how proposition X can be true.
Premise 2: if I can’t explain or imagine how a certain proposition could be true, then it must be false.
Conclusions: proposition X is false.
A similar phrasing can be used in order to argue that a certain proposition is true, in cases where the person in question can’t explain or imagine how it could be false.
When the argument of incredulity is used, premise 1 is usually stated explicitly. This premise can be considered sound, if the speaker can truthfully state that they are unable to see how a certain proposition could be true. This is the case even if there is clear evidence that shows that that proposition is true, since this premise depends on what the speaker knows, rather than on the state of things in reality.
Premise 2, on the other hand, is usually implicit, and is logically unsound, since one’s ability to explain how a certain proposition could be true or false doesn’t necessarily determine whether that proposition is true or false in reality.
Accordingly, the argument from incredulity as a whole is always logically unsound, since there is an issue with a premise that is used to support its conclusion. This means that the argument from incredulity represents an informal logical fallacy, and that we therefore can’t be sure whether its conclusion is true.
Keep in mind that it’s acceptable to be incredulous of something, and to bring this up as part of an argument. The issue with doing so occurs when someone incorrectly assumes that their incredulity means that their preferred explanation must necessarily be right, in terms of a certain theory being true or false. This is especially problematic in situations where the incredulity isn’t justified or supported by evidence, but even when incredulity is justified, it’s still wrong to assume that it means that a preferred explanation must necessarily be right.
Note: the argument from incredulity is sometimes referred to using other names, such as the argument from personal incredulity, the appeal to personal incredulity, the personal incredulity fallacy, and the incredulity fallacy.
Examples of the argument from incredulity
A simple example of the argument from incredulity appears in the case of someone who says “I can’t believe that their story could possibly be false, so it must be true”.
In addition, other examples of the argument from incredulity appear in a variety of situations, many of which include an attempt to discredit or refute a scientific theory. For instance:
“I can’t imagine how humans could have evolved from single-celled organisms; it just doesn’t make sense to me. There is no way that the theory of evolution is right.”
This illustrates how the use of arguments from incredulity is often based on a speaker’s misunderstanding of a topic, or on gaps in their knowledge, rather than on a theory being truly impossible to explain or believe. This means that people who use this fallacy often resort to it even when there is a perfectly valid explanation available for what is being discussed.
Furthermore, people using their personal incredulity in a fallacious manner will often offer an alternative explanation for what’s being discussed, if they believe that the current explanation for the phenomenon is false. For example:
“I just don’t see how vaccines can be safe for children; they must be seriously dangerous in some way. The only reason doctors push for vaccination is because they get paid to do it by the big pharma companies.”
Finally, another example of the argument from incredulity appears in a notable subtype of this fallacy, and specifically in the divine fallacy, which occurs when someone assumes that a certain phenomenon must occur as a result of divine intervention or a supernatural force, either because they don’t know how to explain it otherwise, or because they can’t imagine that this isn’t the case. For instance:
“There is just no way that the concept of evolution is right; it just doesn’t make any sense to me. Creationism is a much better explanation of how we came to be.”
Note: as these examples show, the argument from incredulity is often mentioned in conjunction with the argument from ignorance, which is based on the faulty premise that something can be assumed to be true or false simply due to lack of evidence to the contrary.
How to counter an argument from incredulity
There are several things that you can do in response to an argument from incredulity.
First, you should explain why this sort of reasoning is fallacious. To do this, you should point out the problematic premise of the argument from incredulity, and namely the assumption that the inability to believe that something is true means it must be false and vice versa. You can also point out exactly how this assumption appeared in the present argument from incredulity, or use relevant counterexamples to illustrate the issues with this way of thinking.
Second, you can ask your opponent to justify their reasoning. You can do this by asking them to support their initial assertion, and explain why they are incredulous, and why they think that this validates their position. Furthermore, if they suggest an alternative explanation for the phenomenon that’s being discussed, you can ask them to provide evidence in support of this alternative explanation. When doing this, don’t be unnecessarily confrontational; in many cases, it’s more productive to show the other person that you’re truly willing to listen to what you have to say, since this can make them more willing to engage in dialogue, and more open to internalizing errors in their logic.
Finally, you can provide evidence that shows that their belief is wrong. For example, if someone is using the argument from incredulity because they don’t understand a certain scientific theory, you can explain to them how that theory works, and show them evidence that supports the theory. When doing this, you should make your explanation as simple as possible given the circumstances, since overly complex explanations can be ineffective or even counterproductive; this also applies to the techniques that you use to counter the argument from incredulity, such as explaining why this sort of reasoning is flawed.
However, remember that the burden of proof generally rests on the person using the argument from incredulity. That is, even if you can’t explain a certain phenomenon yourself, or even if science doesn’t know how to explain it yet, that doesn’t mean that the person using the argument from incredulity is necessarily right, and it doesn’t render their fallacious reasoning logically sound.
Finally, when responding to an argument from incredulity, it’s important to remember that it’s possible that the person using the argument from incredulity is right, despite the fact that their reasoning is flawed. This is because, no matter how weak an argument is, it can still have a true conclusion, even if this conclusion is based on faulty premises or faulty argumentation in general. Assuming that someone’s conclusion must be false just because they used the argument from incredulity or some other logical fallacy is fallacious in itself, and is something that you should avoid.
Overall, to counter an argument from incredulity, you can explain why this reasoning is fallacious, ask your opponent to justify their position, and provide evidence showing that the belief in question is wrong, while avoiding overly complex explanations.
Intentional and unintentional arguments from incredulity
When countering the argument from incredulity, it’s important to remember that many people might use it without being aware that they are doing so, and without being aware that it’s fallacious.
Therefore, you should implement Hanlon’s razor, and assume that a person’s use of the argument from incredulity is unintentional, as long as it’s reasonable to do so. Responding to people while maintaining this approach can be beneficial when it comes to engaging in a productive dialogue, which will make your opponent more willing to listen to what you have to say. In addition, this can be beneficial when there are other people watching the discussion involving the argument from incredulity, since it shows your willingness to discuss the topic in an open, non-hostile manner.
At the same time, however, it’s important to keep in mind that people might sometimes use the argument from incredulity intentionally, even if they’re aware of the logical flaw in their argument. Furthermore, there are some cases where the person using the argument from incredulity is not going to change their mind, regardless of what you say.
In such situations, it’s sometimes preferable to simply disengage from the argument, since nothing that you say could help change the other person’s mind. However, there are situations where it’s still worthwhile to continue discussing the topic regardless of this issue, such as when there are other people watching the discussion, who are open to listening to your perspective.
How to avoid using the argument from incredulity yourself
To avoid using the argument from incredulity yourself, you should familiarize yourself with this fallacious pattern of thinking, so you can recognize situations where you’re about to use it, or have used it already. In particular, you should be wary of situations where your rationale is based on one of the following arguments, or on some variant of them, either explicitly or implicitly:
“I can’t imagine how X could be true; therefore, X must be false.”
“I can’t imagine how X could be false; therefore, X must be true.”
When in doubt, try to slow down your reasoning process, and break down your argument by clearly outlining what your premises are and what your conclusion is. If you notice yourself using your incredulity as justification for believing that something must necessarily be true or false, then that means that you’re using the argument from incredulity, and that you need to adjust your reasoning.
In addition, note that even though it can be beneficial to provide additional justification or evidence in support of your incredulity, the key to avoiding fallacious reasoning in this case is to avoid treating your incredulity as definite proof by itself.
Overall, to avoid using the argument from incredulity yourself, you should familiarize yourself with this pattern of thinking, and try to identify cases where you rely on it; when doing this, it can be beneficial to break down your argument, by clearly outlining your premises and conclusion.
Summary and conclusions
- The argument from incredulity is a logical fallacy that occurs when someone concludes that since they can’t believe something is true, then it must be false, and vice versa.
- For example, someone using the argument from incredulity might claim that since they don’t see how a certain scientific theory could be true, then it must be false.
- This way of thinking is fallacious, since someone’s inability to believe that something could be true, does not mean that it must be false, just as someone’s inability to believe that something could be false, does not mean that it must be true.
- To counter an argument from incredulity, you can explain why this reasoning is fallacious, ask your opponent to justify their position, and provide evidence showing that the belief in question is wrong, while avoiding overly complex explanations.
- To avoid using the argument from incredulity yourself, you should familiarize yourself with this pattern of thinking, and try to identify cases where you rely on it; when doing this, it can be beneficial to break down your argument, by clearly outlining your premises and conclusion.