Question-Begging Arguments

​When someone uses their conclusion as one of their premises, they have a valid argument. If all the premises are true, then of course the conclusion must be true too, if the conclusion is just a restatement of one of the premises.

The simplest sort of question-begging argument is an argument where the conclusion simply repeats the premise. So,

P1) Joe Biden is the president of the US.
                                              
C) Joe Biden is the president of the US.

Such an argument is valid, and the premise is true (at the time of writing), so it is sound argument. It is, however, totally useless. The general purpose of arguments is to persuade people of things. This argument cannot be used to persuade anyone of anything, because no one would accept the premise unless they already accepted the conclusion. The failure of question-begging arguments lies not in some technical failure in structure, but in the way they fail to serve the purpose of arguments.

Here’s an only slightly more complex example:

The sky is blue, and the grass is green, therefore the sky is blue. 

This is valid. And its premises are true. However, it is not a good argument. You’re not going to convince anyone who is in doubt about the blueness of the sky by presenting this argument, because for someone to be convinced by an argument they have to accept the premises and then see that the premises give reason to believe the conclusion. But no-one who doesn’t believe the conclusion already will accept the premises of this argument, since the conclusion is one of the premises. This is also a question-begging argument.

No-one would mistake the argument about the blueness of the sky for a good argument. Real-life question-begging tends to be a bit more subtle, and can be a way of trying to disguise the fact that you don’t have a good argument for the thing that you are trying to get someone to believe.

Here is an example:

Abortion is wrong, for it is always wrong to voluntarily and purposefully destroy a living and growing human foetus. 

In this argument, the conclusion (“Abortion is wrong”) is just a restatement of the premise in different words. “The voluntary and purposeful destruction of a living and growing human foetus” is just a more emotive way of saying “abortion.” So unless you already believed the conclusion, you would never accept the premise.

If you think about what the point of giving an argument is, you will see why this is problematic. Generally, when we give an argument, we are trying to persuade someone of a conclusion that they don’t already believe. We do it by providing premises that they are inclined to believe, and then showing them that if they accept those premises, then really they ought to accept the conclusion as well. A question-begging argument can’t be used in this way, because there is no one in the target position – no one who believes the premises but doesn’t believe the conclusion – since the conclusion is one of the premises.

Another, slightly more subtle, example:

God exists. We know this to be true, since the Bible tells us that God exists. And we know that what the Bible tells us is true, since the Bible is the word of God. 

Putting this in standard form:

P1. The Bible is the word of God
P2. If the Bible is the word of God, then what the Bible tells us is true.
                                   
C1. What the Bible tells us is true.
P3. The Bible tells us that God exists.
                                   
C. God exists.

This one is more complicated. The premises don’t explicitly include the claim that God exists. But they do presuppose it. If you didn’t already think there was a God (which is to say, if you didn’t already believe the conclusion), you wouldn’t accept the premise “The Bible is the word of God.” The argument is question-begging – it assumes the very thing that it is trying to prove. Question-begging arguments are sometimes called circular arguments, and you can see why in this example – it argues in a circle, starting from the existence of God and ending up back where it started, at the existence of God.

Question-begging arguments are a reminder that soundness and cogency, while useful, are not the only things that we should consider when assessing arguments.