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Logic:I don't understand circular reasoning. Can you guys give me some example?

  1. Jun 21, 2010 #1
    I still don't understand circular reasoning. Can you guys give me some example?
    From Physics section:"Wave is something satisfying wave equations". I don't know why this sentence is "circular".
  2. jcsd
  3. Jun 21, 2010 #2
    It's circular if the companion definition is "A wave equation is something that describes a wave." That's easy. But a longer chain of apparently 'linear' definitions can in fact be a circle. There's a theory that all definitions in a natural language are circular. In symbolic logic one can assure the existence of a non circular 'definition' by employing an infinite series of unique symbols based on the natural numbers .
    Last edited: Jun 21, 2010
  4. Jun 21, 2010 #3
    Hmm.... that seems more like a tautology than circular reasoning. Based on what you quoted, I'd say it is wrong.

    Circular reasoning is more like this:

    We know the bible is the word of god, because the bible says so, and it must be true, because its the word of god.
  5. Jun 22, 2010 #4


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    The problem with circular reasoning is that the statements "proved" cannot be incorporated into a larger array of statements which one considers true. If the statements doesn't follow from a more general theory of waves, then we cannot necessarily assume them consistent with this larger theory. They can only be considered as consistent with each other.

    The circularity can however be treated as axiomatic in the sense that the theory of waves that follows from the wave equation are supposing that a wave satisfies the wave equation. The circularity can be seen as a ramp; whenever you accept it by "entering the circle", a larger body of implications can be treated as true.
    Last edited: Jun 22, 2010
  6. Jun 22, 2010 #5
    Do you think its more wave-like than circular?
  7. Jul 24, 2010 #6
    Circular reasoning is that you come up with a reasoning that draws a conclusion, but hidden in the reasoning the conclusion was already presupposed.
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