Begging the question
Begging the question, in modern popular usage, is often used synonymously for "raising the question". However the original meaning is quite different: it described a type of logical fallacy (also called 'petitio principii') in which the evidence given for a proposition as much needs to be proved as the proposition itself. A common form of begging the question is a circular argument, circulus in probando, vicious circle or circular reasoning in which the proposition to be proved is contained in one of the premises. As a concept in logic it was first identified by the Greek philosopher Aristotle around 350 B.C., in his book Prior Analytics.
Confusion in the term "begging the question"
Part of the reason for the misunderstanding over "begging the question" may be due to the term itself, which was translated into English from Latin in the 16th century. The Latin version, Petitio Principii, could be translated more accurately as "petitioning the principle," meaning claiming the truth of the very matter in question, but the more pithy "begging the question" has become the well-known translation.
The two meanings ("begging the question" and "raising the question") are discussed below.
Begging the Question and Circular argument
A circular argument is one which assumes the very thing it aims to prove; in essence, the proposition is used to prove itself, a tactic which in its simplest form is not very persuasive. For example here is an attempt to prove that Paul is telling the truth:
- Suppose Paul is not lying when he speaks.
- Whoever speaks and is not lying is telling the truth.
- Therefore, Paul is telling the truth.
These statements are logical, but they do nothing to convince one of the truthfulness of the speaker. The problem is that in seeking to prove Paul's truthfulness, the speaker asks his audience to assume that Paul is telling the truth, so this actually proves "If Paul is not lying, then Paul is telling the truth."
It is important to note that such arguments are logically valid. That is, the conclusion does in fact follow from the premises, since it is in some way identical to the premises. All circular arguments have this characteristic: that the proposition to be proved is assumed at some point in the argument.
Strictly speaking, a circular argument has the following structure. For some proposition p
- p implies p
- suppose p
- therefore, p
The syntactic presentation of circular reasoning is rarely this transparent, as is shown, for example, in the above argument purportedly proving Paul is telling the truth.
The broader category of begging the question (of which a circular argument is a species) includes arguments that do not include the conclusion as one of the premises but do include a premise that is at least as dubious as the proposed conclusion. For example, the statement that one should not walk in the woods alone at night because Fairies are likely to bewitch you is an example of begging the question that is not a circular argument.
Another example of begging the question is reducing an assertion to an instance of a more general assertion whose truth is not any more proved.
- All intentional acts of killing human beings are morally wrong.
- The death penalty is an intentional act of killing a human being.
- Therefore the death penalty is wrong.
This reasoning is valid; moreover the first premise is strictly stronger than the conclusion. Indeed the first premise may be harder (or impossible) to prove, since it quantifies over many different kinds of intentional acts of killing human beings, such as acts of self-defense.
Note, however, that reduction to a more general premise is often useful, particularly in mathematics: For instance, to prove that the sum of the first 244 integers is 29890, it is often easier to first prove a more general assertion, such as
- The sum of the first n integers equals .
Raising the question
In much modern usage, sometimes criticized, the phrase has nothing to do with arguments in logic at all and merely refers to raising an issue. For instance: "This year's budget deficit is half a trillion dollars. This begs the question: how are we ever going to balance the budget?" Because many authorities desire to preserve the use of the term to designate a type of logical error, a careful writer may prefer to write "this raises the question" instead.