Begging the question (or petitio principii, "assuming the initial point") is a type of logical in which the proposition to be proved is assumed implicitly or explicitly in the premise. The first known definition in the West is by the Greek philospher Aristotle. Begging the question is related to the circular argument or circular reasoning, though these are considered absolutely different by Aristotle.
Begging or assuming the point at issue consists (to take the expression in its widest sense) of failing to demonstrate the required proposition.
The fallacy of petitio principii, or "begging the question", is committed "when a proposition which requires proof is assumed without proof. More specifically, petitio principii refers to arguing for a conclusion that has already been assumed in the premise, in effect "begging" any listener to "question" the basis of the logic. The fallacy may be committed in various ways.
The fallacy of begging the question is sometimes committed in a single step as in the statement "Opium induces sleep because it has a soporific quality". Such fallacies may not be immediately obvious in English because the English language has many synonyms; one way to beg the question is to make a statement first in concrete terms, then in abstract ones, or vice-versa. Another is to "bring forth a proposition expressed in words of Saxon origin, and give as a reason for it the very same proposition stated in words of Norman origin",as in this example: "To allow every man an unbounded freedom of speech must always be, on the whole advantageous to the State, for it is highly conducive to the interests of the community that each individual should enjoy a liberty perfectly unlimited of expressing his sentiments. When the fallacy of begging the question is committed in more than one step, it is sometimes referred to as or reasoning in a circle.
"Begging the question" can also refer to making an argument in which the premise is different from the conclusion but is controversial or questionable for the same reasons that typically might lead someone to question the conclusion.
.... seldom is anyone going to simply place the conclusion word-for-word into the premises .... Rather, an arguer might use phraseology that conceals the fact that the conclusion is masquerading as a premise. The conclusion is rephrased to look different and is then placed in the premises.
Person 1: He is annoyed right now. Person 2: How do you know? Person 1: Well, because he is really angry.
In informal situations, the term begging the question is often used in place of circular argument. In the formal context however, begging the question holds a different meaning. In its shortest form, circular reasoning is the basing of two conclusions by means of which there is demonstrated a reversed premise of the first argument. Begging the question does not require any such reversal.
Begging the question is similar 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, rather 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 wrong.
If the first premise is accepted as an axiom within some moral system or code, this reasoning is a cogent 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
Some English speakers assume "beg the question" means "raise the question" and use it so: for example, "this year's deficit is half a trillion dollars, which begs the question: how are we ever going to balance the budget?" Many usage commentators deem such usage incorrect.