Begging the question

In logic, begging the question has traditionally described a type of logical fallacy (also called petitio principii) in which the proposition to be proved is assumed implicitly or explicitly in one of the premises. Begging the question is related to the fallacy known as circular argument, circulus in probando, vicious circle or circular reasoning. The first known definition in the West is by the Greek philosopher Aristotle around 350 B.C., in his book Prior Analytics.

In recent decades, "begs the question" has been used to mean that a statement invites another obvious question. It is undisputed that while initially this usage was incorrect, its prevalence in modern usage is arguably developing a second meaning to the classic phrase.

History

The Latin term was incorporated into English in the 16th century. The Latin version, Petitio Principii (from peto, petere, petivi, petitus: attack, aim at, desire, beg, entreat, ask (for), reach towards, make for; principii, genitive of principium: beginning or principle), literally means "begging or taking for granted of the beginning or of a principle." That is, the premise (the principle, the beginning) depends on the truth of the very matter in question. The Latin phrase comes from the Greek en archei aiteisthai in Aristotle's Prior Analytics II xvi:

Begging or assuming the point at issue consists (to take the expression in its widest sense) in failing to demonstrate the required proposition. But there are several other ways in which this may happen; for example, if the argument has not taken syllogistic form at all […]. If, however, the relation of B to C is such that they are identical, or that they are clearly convertible, or that one applies to the other, then he is begging the point at issue.

Fowler's Deductive Logic (1887) argues that the Latin origin is more properly Petitio Quæsiti which translates as "begging the question".

An example

"That begs the question" is an appropriate reply when a circular argument is used within one syllogism. That is, when the deduction contains a proposition that assumes the very thing the argument 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.
• Paul is speaking.
• 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."

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 self-circular arguments have this characteristic: that the proposition to be proved is assumed at some point in the argument.

Formally speaking, the fallacy of petitio principii has the following structure: For some proposition p,

• p implies q
• suppose p
• therefore, q.

The syntactic presentation of the fallacy is rarely this transparent, as is shown, for example, in the above argument purportedly proving Paul is telling the truth.

Variations

In a related sense, the phrase is occasionally used to mean "avoiding the question". Those who use this variation are explaining that the argument lacks a premise, and they have missed the self-circularity of the argument because of it.

Fowler's Modern English Usage classifies begging the question in a somewhat different fashion (for example, in contrast to the meanings from Merriam-Webster,[1] the Oxford English Dictionary, and the American Heritage Dictionary). Fowler states that it is "The fallacy of founding a conclusion on a basis that as much needs to be proved as the conclusion itself." This is more commonly known as the fallacy of many questions.

Related Fallacies

Begging the question is related to the fallacy of circular reasoning. The distinction between the two concepts is as follows: Circular reasoning is the basing of two conclusions each upon the other (or possibly with more intermediate steps). That is, if you follow a chain of arguments and conclusions (a proof or series of proofs), one of the conclusions is presumed by an earlier conclusion. Begging the question can occur within one argument and consequent conclusion. In strict sense, begging the question occurs if and only if the conclusion is implicitly or explicitly a component of an immediate premise. It is usually accepted, though, to use the term begging the question in place of circular argument.

Begging the question is also related to the fallacy of many questions — a fallacy of technique that results from presenting evidence (in support of a conclusion) that is less likely to be accepted than merely asserting the conclusion.

A specific form of this is reducing an assertion to an instance of a more general assertion which is no more known to be true than the more specific assertion:

• 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 morally wrong.

If the first premise is accepted as an axiom within some moral system or code, this reasoning is a sound argument against the death penalty. If not, it is in fact a weaker argument than a mere assertion that the death penalty is wrong, since the first premise is stronger than the conclusion.

Modern usage controversy

More recently, to beg the question has been increasingly used by some as a synonym for "to raise the question", or "the question really ought to be addressed" An example of such a usage would be, "This year's budget deficit is half a trillion dollars. This begs the question: how are we ever going to balance the budget?"

A possible origin for this confusion in usage is the likeness of the word "beg" to the word "beget", which can mean "to originate." The phrase "to beget the question" might have been confused in time with the similar-sounding (but very different) notion from logic "to beg the question". An example of this usage is found in An Enquiry Concerning Human Understanding by David Hume, published in 1748: "This begets a very natural question; What is meant by a sceptic?" (Section XII).

Arguments over such usage are an example of debate over linguistic prescription and description.

See also

• Fallacy of many questions
• Fallacies of definition
• Catch 22
• Circular definition
• Regress argument (diallelus)