Begging the Question

Wizard Web
Latin: Petitio Principii

Begging the Question is circular logic in which an essential premise to the conclusion is itself, stated without support. It has nothing to do with begging for a question, as in common misuse. The "question" is the matter or subject at hand, and the "begging" can be thought of a metaphorical attempt to get it for free. The Latin petitio principii with the English cognate "petitioning the principle" is more appropriate but less colorful.

Circular Reasoning

Wizard [Web]

Latin: circulus in demonstrando, circulus in probando

Circular logic is relying on a proposition for one of its premises.

Fallacy Files:

For an argument to have any epistemological or dialectical force, it must start from premisses already known or believed by its audience, and proceed to a conclusion not known or believed. This, of course, rules out the worst cases of Begging the Question, when the conclusion is the very same proposition as the premiss, since one cannot both believe and not believe the same thing. A viciously circular argument is one with a conclusion based ultimately upon that conclusion itself, and such arguments can never advance our knowledge.

All circular logic is not Begging the Question, but used fallaciously the terms are effectively synonymous. If a premise is not truly needed to establish a proposition, then its circular nature reinforces rather than fools. Use with care, if only because an unscrupulous opponent may charge circularity.

Circular logic is not always fallacious. For instance, we know that 2 + 2 = 4 in part because 4 - 2 = 2.

The best use of circular logic, however, is indirect: if in reasoning back to our premises we encounter a contradiction, reductio ad absurdum alerts us to an error somewhere, either in our reasoning or premises. Care must be exercised here as well, because we may not find an error but still have a false conclusion. Something external to the loop must validate it, and nothing must invalidate it.

Shifting the Burden of Proof

Shifting the Burden of Proof is employed in two ways: by an arguer, to more easily establish a claim, and by an audience, to make it more difficult.

When employed by an arguer, too much of the conclusion is assumed, rather than being established. A special case is when (all or part of) the conclusion itself is assumed and used as a premise in the argument, which is called circular reasoning or Begging the Question.

When employed by an audience, the burden is set impossibly high. An arguer may be told that he must have a solid case proved before he can plead it.

Questions over where the burden of proof belongs (outside the legal system, which has explicit rules about it) can be easily answered with the question, "Who needs to be convinced?"

Burden of Proof

The burden of proof is always on the assertion. That is, to the degree that an argument rests on some premise, to complete the argument requires establishing the premise. Failing to take on the burden of proof will mean convincing only those who already agree.

One can assume a premise as obvious, and the relative importance of that premise to the argument is the degree to which the argument employs the fallacy of Begging the Question or circular reasoning.

In most cases, we use informal logic (in essays or scientific writing) to convince the reader of some case we are building. To convince all readers, we must be sure that all readers accept all of our premises, or we dismiss those readers who do not accept our premises.

Some assumed premises are left unstated: if the world continues to revolve, if the area of a circle really does equal πr², and so on. Depending on audience, subject matter, skill of the arguer, and how important a premise is to an argument, it may be left unstated or it may require extensive proof, or anything in between.

In political or theological debates, it is quite common for an argument to be built on an entire unstated framework of belief. Here again, to complete the argument requires establishing the premises.

See also Shifting the Burden