Difference between revisions of "Circular reasoning"

Revision as of 20:18, November 23, 2009

Something Christians use all the time.

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-'''Circular reasoning''' is a form of [[Logical fallacy#Proof by assertion|proof by assertion]] in which one uses a conclusion of an argument as the [[premise]] to that same argument. This is also known as ''petitio principii'' or ''begging the question.''
+Something Christians use all the time.
-It is considered invalid and therefore is not permitted by the rules of [[formal logic]].
-== An analysis ==
-The simplest argument is a single inference, as per the Law of Detachment:
-*If P, then Q.
-*P.
-*Therefore, Q.
-The Law of the Syllogism uses Detachment to establish an ''intermediate'' conclusion between the original premise and the eventual conclusion. Thus:
-*If P, then Q.
-*If Q, then R.
-*Therefore, if P, then R.
-*P.
-*Therefore, Q and R.
-''Contraposition'' uses Detachment in reverse to show that a thing is ''not'' true:
-*If P, then Q.
-*Not Q.
-*Therefore, not P.
-All these proofs start with a proposition already verified or denied.
-This is the classic structure of circular reasoning, that is an abuse of the Law of the Syllogism:
-*If P, then Q.
-*If Q, then R.
-*If R, then P.
-*P.
-*Therefore, Q.
-*Therefore, R.
-*Therefore, P.
-Each of these three conditional statements would be valid by itself. Together, they create a flawed argument, because P now depends on itself to be true. The line of reasoning ends where it began, and is thus a circle. The only difference between this and ''proof by assertion'' is that the latter attempts to use a single conditional statement--"if P, then P"--while circular reasoning uses at least two, and typically three or more, syllogisms.
-Circular arguments can be very difficult to detect. Circular arguments found in the professional literature, or in [[propaganda]], typically use five or six (or more) syllogisms.
-Every logical system ''must'' begin with a set of generally accepted assumptions called ''postulates'' or ''axioms'' (from the [[Greek]] '''αξιος''' or ''axios'' worthy or deserving). Similarly, any set of definitions must start with a set of fundamental terms that need no definition. An axiom is usually a fundamental property of nature upon which all agree. Persons attempting to show that something is a fundamental property of nature when it is not, or a value of that property that is contrary to fact, typically use circular reasoning to make such an attempt.
-== Reference ==
-* [http://creationwiki.org/Circular_reasoning Circular reasoning] by [[CreationWiki]]
-[[Category:Logical Fallacies]]

Difference between revisions of "Circular reasoning"

Revision as of 20:18, November 23, 2009

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