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Begging the Question (Petitio Principii)

Fallacies of Presumption


Fallacy Name:
Begging the Question

Alternative Names:
Petitio Principii
Circular Argument
Circulus in Probando
Circulus in Demonstrando
Vicious Circle

Fallacy of Weak Induction > Fallacy of Presumption

This is the most basic and classic example of a Fallacy of Presumption, because it directly presumes the conclusion which is at question in the first place. This can also be known as a "Circular Argument" - because the conclusion essentially appears both at the beginning and the end of the argument, it creates an endless circle, never accomplishing anything of substance.

A good argument in support of a claim will offer independent evidence or reasons to believe that claim. However, if you are assuming the truth of some portion of your conclusion, then your reasons are no longer independent: your reasons have become dependent upon the very point which is contested. The basic structure looks like this:

1. A is true because A is true.

Examples and Discussion

Here is an example of this most simple form of begging the question:

2. You should drive on the right side of the road because that is what the law says, and the law is the law.

Obviously driving on the right side of the road is mandated by law (in some countries, that is) - so when someone questions why we should do that, they are questioning the law. But if I am offering reasons to follow this law and I simply say "because that is the law," I am begging the question. I am assuming the validity of what the other person was questioning in the first place.

3. Affirmative Action can never be fair or just. You cannot remedy one injustice by committing another. (quoted from the forum)

This is a classic example of a circular argument - the conclusion is that affirmative action cannot be fair or just, and the premise is that injustice cannot be remedied by something that is unjust (like affirmative action). But we cannot assume the unjust-ness of affirmative action when arguing that it is unjust.

However, it is not usual for the matter to be so obvious. Instead, the chains are a bit longer:

4. A is true because B is true, and B is true because A is true.
5. A is true because B is true, and B is true because C is true, and C is true because A is true.

More Examples and Discussion:

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