A circular reasoning , circular proof , logical circle , circular closure or also hysteron proteron (from ancient Greek ὕστερον πρότερον hýsteron próteron , literally "the later [is] the earlier" ) is a proof error in which the prerequisites already contain what is to be proven. So it is claimed to prove a proposition by deduction using the proposition itself as a premise. It is also known as Circulus Vitiosus (from Latin circulus vitiosus , literally incorrect circle ) or vicious circle .
However, the vicious circle in the sense of system therapy as a self-reinforcing feedback pattern in communication must be distinguished from this. A rhetorical figure that can be distinguished from the circular argument is now referred to as hýsteron próteron . The related case of a self-referential definition is dealt with under Idem per idem . In a certain sense, the Petitio Principii is a special case of the circular argument, in which the admission of the presupposed statement in the course of a dialogical argument is subsequently demanded, often hidden in a more general thesis.
In circular reasoning , a thesis is derived in an argument by inferring from premises whose validity is just as questionable as that of the thesis, even if they sound more credible or give the impression of being valid regardless of the acceptance of the thesis. This represents a violation of the principle of sufficient reason . The self-reference can also take place over several stages, so that the circular reasoning remains hidden from the careless observer, or even from the author himself.
Circular inference is only erroneously a legitimate form of logical inference; the logical circle is the fifth of the Five Tropics of Agrippa and an element of the Münchhausen Trilemma . If it is used in Eristics or Elenkik , it is a special case of the Petitio Principii .
The Bible is God's word because it is written "all scripture is inspired by God".
This argument quotes the 2nd letter to Timothy LUT from the New Testament ; Since the New Testament is part of the Christian Bible , the authority of the Bible is established by a quotation from the Bible. The Bible thus draws its authority as the word of God from within itself. In addition, the quote is only an argument ad verecundiam , since it comes from a special letter of the Apostle Paul , so a logically not compelling rhetorical figure. Thus one could take the position that the reasoning is not self-referential: the canon of the Christian Bible did not yet exist when Paul wrote the 2nd Timothy. But according to this, the author of the letter would probably have meant the Tanach by “all scriptures” .
Molière aptly mocked this kind of logical error in one of his comedies: the father of a dumb daughter wants to know why his daughter is dumb. “Nothing easier than that,” replies the doctor, “it depends on the ability to speak.” “Of course, of course,” replies the father, “but please tell me why she lost the ability to speak?” The doctor replied : "All of our best writers tell us that it depends on the inability to master the language."
“If, for example, a court finds that a witness is credible, but only refers to the statements of the witness himself, whose credibility is at issue, then at least the suspicion that the judgment on the credibility of the witness had already been made before his statement was considered more closely. "( Joerden : Logic in Law )
The snake devouring itself from its tail The motif of the Ouroboros illustrates the circular argument graphically: The snake consumes itself, that which has to be proven
There's a hole in the bucket (self-presupposing act)
The folk song A Hole is in the Bucket describes a solution to a problem which, over several steps, ultimately presupposes that it has already been solved.