Editing Begging the question (section)

== Definition ==
To {{gloss|beg the question}} (also called {{lang|la|petitio principii}}) is to attempt to support a claim with a premise that itself restates or presupposes the claim.<ref name="Welton279">Welton (1905), 279., "{{lang|la|Petitio principii}} is, therefore, committed when a proposition which requires proof is assumed without proof."</ref> It is an attempt to prove a proposition while simultaneously taking the proposition for granted.

When the fallacy involves only a single variable, it is sometimes called a ''[[hysteron proteron]]''<ref name="Davies572">Davies (1915), 572.</ref><ref name="Welton280">Welton (1905), 280–282.</ref><ref>In [[Molière]]'s ''[[The Imaginary Invalid|Le Malade imaginaire]]'', a quack "answers" the question of "Why does [[opium]] cause sleep?" with "Because of its [[Hypnotic|soporific]] power." In the original: {{lang|fr|Mihi a docto doctore / Demandatur causam et rationem quare / Opium facit dormire. / A quoi respondeo, / Quia est in eo / Vertus dormitiva, / Cujus est natura / Sensus assoupire.}} [http://fr.wikisource.org/wiki/Le_Malade_imaginaire_-_3%C3%A8me_interm%C3%A8de ''Le Malade imaginaire'' in French Wikisource]</ref> (Greek for {{gloss|later earlier}}), a [[rhetoric]]al device, as in the statement:
{{blockquote|Opium induces sleep because it has a <abbr title{{=}}"sleep-inducing">[[wikt:soporific|''soporific'']]</abbr> quality.<ref name="Welton281">Welton (1905), 281.</ref>}}

Reading this sentence, the only thing one can learn is a new word (soporific) that refers to a more common action (inducing sleep); it does not explain why opium causes that effect. A sentence that explains why opium induces sleep (or the same, why opium has soporific quality) could be the following one:

{{blockquote|[[Opium]] induces sleep because it contains [[morphine-6-glucuronide]], which inhibits the brain's receptors for pain, causing a pleasurable sensation that eventually induces sleep.}}

A less obvious example from ''Fallacies and Pitfalls of Language: The Language Trap'' by S. Morris Engel:

{{blockquote|Free trade will be good for this country. The reason is patently clear. Isn't it obvious that unrestricted commercial relations will bestow on all sections of this nation the benefits which result when there is an unimpeded flow of goods between countries?<ref>{{Cite book|last=Engel|first=S. Morris|url=https://www.worldcat.org/oclc/30671266|title=Fallacies and pitfalls of language : the language trap|date=1994|publisher=Dover Publications|others=S. Morris Engel|isbn=0-486-28274-0|location=New York|oclc=30671266}}</ref>}}

This form of the fallacy may not be immediately obvious. Linguistic variations in syntax, sentence structure, and the literary device may conceal it, as may other factors involved in an argument's delivery. It may take the form of an unstated premise which is essential but not identical to the conclusion, or is "controversial or questionable for the same reasons that typically might lead someone to question the conclusion":<ref>Kahane and Cavender (2005), 60.</ref>

{{blockquote|...{{nbsp}}[S]eldom is anyone going to simply place the conclusion word-for-word into the premises{{nbsp}}... 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.|Paul Herrick<ref name="Herrick248"/>}}

For example, one can obscure the fallacy by first making a statement in concrete terms, then attempting to pass off an identical statement, delivered in abstract terms, as evidence for the original.<ref name="Welton281" /> One could also "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 language|Norman]] origin",<ref>Gibson (1908), 291.</ref> as here:

{{blockquote|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."<ref>[[Richard Whately]], ''Elements of Logic'' (1826) quoted in Gibson (1908), 291.</ref>}}

When the fallacy of begging the question is committed in more than one step, some authors dub it {{lang|la|circulus in probando}} {{gloss|reasoning in a circle}},<ref name="Davies572" /><ref name="Dowden">Bradley Dowden, [http://www.iep.utm.edu/fallacy/#BeggingtheQuestion "Fallacies"] in ''Internet Encyclopedia of Philosophy''.</ref> or more commonly, ''circular reasoning''.

Begging the question is not considered a [[formal fallacy]] (an [[argument]] that is defective because it uses an incorrect [[deductive reasoning|deductive step]]). Rather, it is a type of [[informal fallacy]] that is [[Validity (logic)|logically valid]] but unpersuasive, in that it fails to prove anything other than what is already assumed.<ref>{{cite encyclopedia| encyclopedia=[[Encyclopædia Britannica]] |title=Fallacy |url=https://www.britannica.com/EBchecked/topic/200836/fallacy#ref1102387 |quote=Strictly speaking, {{lang|la|petitio principii}} is not a fallacy of reasoning but an ineptitude in argumentation: thus the argument from p as a premise to p as conclusion is not deductively invalid but lacks any power of conviction since no one who questioned the conclusion could concede the premise.}}</ref><ref name="Walton">{{cite book |title=Plausible argument in everyday conversation |publisher=SUNY Press |author=Walton, Douglas |year=1992 |pages=206–207 |isbn=978-0791411575 |quote=Wellington is in New Zealand. Therefore, Wellington is in New Zealand.}}</ref><ref name="Petitio Principii">The reason {{lang|la|petitio principii}} is considered a fallacy is not that the [[inference]] is invalid (because any statement is indeed equivalent to itself), but that the argument can be deceptive.  A statement cannot prove itself. A premiss{{sic}} must have a different source of reason, ground or evidence for its truth  from that of the conclusion: Lander University, [http://philosophy.lander.edu/logic/circular.html "Petitio Principii"].</ref>