Begging the question
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Begging the question in logic, also known as circular reasoning and by the Latin name petitio principii, is an informal fallacy found in many attempts at logical arguments. An argument that begs the question is one in which a premise presupposes the conclusion in some way. Such an argument is valid in the sense in which logicians use that term, yet provides no reason at all to believe its conclusion.
Today, the phrase is also frequently seen in a different usage with the meaning "raise the question." This usage is contested [1]
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[edit] History
The term was translated into English from the Latin in the 16th century. The Latin version, Petitio Principii (petitio: petition, request; principii, genitive of principium: beginning, basis, premise of an argument), literally means "a request for the beginning or premise." That is, the premise 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, he may argue from premises which are less known or equally unknown, or he may establish the antecedent by means of its consequents; for demonstration proceeds from what is more certain and is prior. Now begging the question is none of these. [...] 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.... [B]egging the question is proving what is not self-evident by means of itself ... either because predicates which are identical belong to the same subject, or because the same predicate belongs to subjects which are identical."
Fowler's Deductive Logic (1887) argues that the Latin origin is more properly Petitio Quæsiti which is literally "begging the question" as opposed to "petitioning the premise."
[edit] Examples
The following argument is a standard example of begging the question: "The Bible says God exists, and the Bible must be right since it is the revealed word of God, so God exists." Obviously enough, no one who doubts the conclusion has any reason to challenge the second premise, which presupposes it. This is, of course, a blatant example meant solely to illustrate the fallacy; less contrived instances may be much more subtle. David Hume's argument against the occurrence of miracles, as articulated in Of Miracles, is often criticized as a subtler example of petitio principii.
Begging the question is sometimes used by lawyers as a rhetorical device to sway jurors. An example occurred during the 2002 trial of the youths originally accused of murdering Damilola Taylor. In his closing comments, the prosecuting QC made much of the fact that the defendants had shown "no remorse" [2], the implied argument being: If these people are guilty and have shown no remorse for their crime, this can only mean that they are bad people, and this strengthens our conviction that they are guilty. (In this case the jury were not fooled; the defendants were all acquitted.)
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 already contained in the premises. All circular arguments have this characteristic: the proposition to be proved is assumed at some point in the argument. This is why begging the question was classified as a material fallacy rather than a logical fallacy by Aristotle, and similarly, is classified as an informal fallacy today.
The logical validity of petitio principii is evident in the use that is made of it in electronic logic circuits. In the simple memory device called a flip flop (sometimes called a bistable multivibrator), two inverting gates are connected back-to-back (the output of each feeds into the input of the other). If the input of one device is 1 (true) its output - and hence the input of the other gate - is 0 (false), causing the output of that gate - and hence the input of the first - to be 1 (true). This situation persists until some external influence forces one of the inputs to change state, from which point onwards the opposite scenario persists. The device therefore stores one "bit" (1 or 0) of information, depending on whether the circuit's "argument" sustains or defeats itself. (A similar circuit called an astable multivibrator does contain a contradiction, and cannot therefore find a stable logical state. Such circuits are used to provide electrical oscillations.)
Formally speaking, the simplest form of begging the question follows the following structure. For some proposition p:
- p implies p
- suppose p
- therefore, p.
However, the following structure is more common:
- p implies q
- q implies r
- r implies p
- suppose p
- therefore, q
- therefore, r
- therefore, p.
[edit] 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 (from, for example, the meanings from Merriam-Webster, the Oxford English Dictionary, and the American Heritage Dictionary). Fowler's states that it is "[t]he 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.
[edit] Related fallacies
Though "begging the question" and "circular reasoning" are often used interchangeably, some textbooks maintain that this is not quite correct in the strictest sense. In this view there is the following difference between them: Circular Reasoning is the basing of two conclusions each upon the other (possibly with one or more intermediate steps). That is, if you follow a chain of arguments, the conclusion of some argument is used as a premise in one of the earlier arguments that eventually led to that conclusion. Begging the question can occur within one argument; on this understanding, begging the question occurs if and only if the conclusion is implicitly or explicitly a component of an immediate premise.
A version of our first example that constitutes circular reasoning in this strict sense would involve asserting both that:
- The Bible tells me that faith in God is a good basis for forming beliefs.
- In general, what the Bible says is true.
- Therefore, faith in God is a good basis for forming beliefs.
and:
- Faith in God is a good basis for forming beliefs.
- My faith in God tells me that, in general, what the Bible says is true.
- Therefore, in general, what the Bible says is true.
[edit] Modern usage
More recently, "begs the question" has been used as a synonym for "invites the question" or "raises the question," or to indicate that "the question ought to be addressed." In this usage, "the question" is stated in the next phrase. For example: "This year's budget deficit is half a trillion dollars. This begs the question: how are we ever going to balance the budget?" Argument over whether this usage should be considered incorrect is an example of the debate between linguistic prescription and description.
