The Argument By Assertion

This post first appeared on Lernabit.com.

The argument by assertion is a fallacy in which someone states that something is true because it is true, regardless of a lack of supporting evidence or even an outright contradiction. In other words, the argument literally states: “This claim is true. Period.” The reverse of this argument is also a fallacy. In other words, stating that something is false without any evidence to support that claim is also an argument by assertion.

If you have listened to the lecture about argument structure, you might recall that a valid argument consists of one or more premises leading up to a conclusion. The reason the argument by assertion is a fallacy is because it is merely a statement without any evidence or logic to support it. In other words, it is just a conclusion without any premises. Thus, an argument by assertion is an incomplete argument, making it logically invalid.

This does not mean that all singular statements are logically invalid. For instance, if I state that birds lay eggs, this might at first seem like an argument by assertion, because I am simply stating something as fact without providing any evidence. But this is not an argument by assertion. The difference between stating a fact and making an argument by assertion is that the fact still has evidence to support it, even if that evidence is not always stated. When making an argument, I might simply state that birds lay eggs without providing evidence, but that evidence does exist and can be provided if needed.

In contrast, an argument by assertion has no such evidence. If I make an argument by assertion, I am claiming something as fact when there is no evidence to support that claim. For example, if I say that the Earth is flat, this is not just me stating a fact. It is making a claim that goes against mountains of evidence to the contrary and has zero evidence to support it. Thus, this is an argument by assertion, and is logically unsound.

A more common form of the argument by assertion is when something is stated to be true simply because it has been asserted so many times by many different people. But just because a claim is believed by many people, that doesn’t make it true. Even if I could get everyone in the world to say that the Earth is flat, the Earth will still be round.

This form of argument by assertion is harder to catch, and even more so now that the Internet makes it so easy for false information to spread. All it takes is one major site to post incorrect information before other sites copy it and spread it further. This makes it complicated to separate fact from fiction, because even if you want to stay critical and skeptical, there simply isn’t enough time in a day to verify every claim everyone makes. At some point you just have to trust the information you have been given, and usually, the verification stops when we reach the point at which the given facts are assumed to be common sense.

Unfortunately, “common sense” is sometimes wrong, because it consists of information that everyone else also assumed to be true, when in fact nobody really bothered to verify it. Thus, arguments by assertion have a tendency to be self-propagating, with so many people assuming something to be true that it becomes recognized as common sense, further reinforcing it as fact even if it is wrong.

The argument by assertion frequently comes off as stubbornness, because it is an unwillingness by someone to change their opinion in the face of new facts that refute their argument. When all of your points have been shot down and you no longer have any evidence to support a claim, it is time to start considering the fact that you might actually be wrong, at least about that one point. But if you continue to insist that you are right, you are not only stubborn, you are also committing the argument by assertion.