Also known as a
circular argument,
begging the question describes a type of
logical fallacy in which the premises in an argument for a proposition contain the proposition itself, and thus are equally doubtful.
In essence, the proposition is used to prove itself, which is neither very persuasive nor logically valid. Further, as the phrase is used in philosophy today, a question-begging argument needn't go so far as to include its conclusion in its premises. Rather, the argument need only rest upon premises so contentious that no detractor of the conclusion would accept them anyway. For example,
The Bible says God exists, and the Bible is always right, therefore God exists begs the question, for no
atheist would accept that the Bible is always right. Though the argument is not circular, it is as good as circular, given the context of the dispute.
The name comes from old Greek ways of arguing - people were to prove or disprove a certain proposition (called 'the question' - which here means 'matter to be discussed').
To do so, they would sometimes make certain statements, which they would ask their opponent to accept as a mutually agreed truth.
If you're begging the question, then you are asking for the proposition itself to be such a 'mutually agreed truth' - and then you cannot be said to have proven it.
An alternative use of the phrase as synonymous with "raises the question," for example, "The recent KKK march begs the question 'when does free speech go too far?'", is regarded by many, especially academics, as substandard.
See also circular definition.