Logical Fallacies 9: Circular Reasoning

Video here:
http://www.youtube.com/watch?v=3DElodsKobQ&feature=watch_response

            A chain of logic is composed of propositions.  A proposition is something which can be true or false.  “George Clooney is a terrible actor” doesn’t count, because it’s a matter of opinion.  It is subject to neither verification, nor falsification; agreement or disagreement, but not verification or falsification.  Ah, but wait.  There’s falsification in the colloquial sense and in the logical and scientific sense.  The sense of the word I’m using here is the latter.  So let me clarify.

            If a thing is proven true, then it is no longer falsifiable in the colloquial sense.  In the colloquial sense, not being falsifiable is a good thing.  The logical and scientific sense is different.

            The only way something can be proven true is if the sort of thing which would prove it false is able to exist.  What if someone offered you a product to re-orient your chakras or make your bodily humors groovy?  To know if it worked, you would have to have a way to know if it didn’t work.  In order for it to really pass the test, it would have to have a way to fail it.  Put another way, in order for a thing to be verifiable, it must also be falsifiable.  The kind of manifestation which would prove it false must be able to exist.  That which is not falsifiable is, therefore, neither verifiable nor testable.  That’s what falsifiability is in the logical and scientific sense of the word.

            A proposition must be something testable.  “Holy Crap!” doesn’t count, but “Crap is holy,” might, depending on how one defines “holy.”  “George Clooney is a terrible actor,” is not, but, “Many people hold the opinion that he is a terrible actor,” is.

            There are two categories of propositions: supporting propositions, also known as premises, and supported propositions, also known as conclusions.

            Example:

            Eight is greater than seven.  Nine is greater than eight.  Therefore, nine is greater than seven.

            This is an example of a single link.  It has two premises, and one conclusion.  But in a chain of logic, a conclusion from one link can serve as a premise in the next.  By the same token, the premises from one link can serve as the conclusions of the previous link.

            Continuing the example:

            Nine is greater than seven.  Ten is greater than nine.  Therefore ten is greater than seven.

            Logic, though, as a rule, in order to be effective and useful, must be linear.  The moment it becomes circular, it ceases to be logic; it ceases to be logical.

            Imagine if you will, a properly-built three-story edifice.  The concrete foundation supports the first floor.  The first floor supports the second.  The second supports the third.  But the first and second cannot be used to support one-another.

            Star Trek: The Motion Picture came to theaters in 1979.  In it, a character named Ilea is accidentally killed by an artificially-intelligent alien vessel.  The vessel then sends back a probe of its own in the form of Ilea to interact with the crew of Enterprise.  They ask the probe, “Who are you?”

            She replies, “I am that which was created by V-Ger.”

            They then ask, “Who is V-Ger?”

            Her answer is, “V-Ger is that which created me.”

            Observe, with this information alone, we are given a clear picture of how the probe and V-Ger relate, but no real, useful insight into the identities of either.  Here we have a logical fallacy called “circular reasoning.”

            Another good example I recall from a comic strip I read, if I recall correctly, leading up to the ‘04 general election.  I don’t remember the exact amendment, but there was something there about making it legal for homosexuals to marry.  One character in the strip insisted that allowing homosexuals to marry just wasn’t right.

            Another character asked why.

            The answer was that it had never happened before.

            The other character asked why that was the case.

            Because it just wasn’t right.

            So it was wrong because it was without precedent and it was without precedent because it was wrong.

            This is a problem in any context, but it’s especially pervasive within religion.  Consider:

            “I know that the Bible is true, because event X was witnessed by 500 people.  I know that event X was witnessed by 500 people because it says so in the Bible which is true.”

            “God made us vulnerable to skin cancer to encourage us to stay out of the sun.  God wants us to stay out of the sun because it causes skin cancer.”

            Two propositions cannot relate to one another as both premise and conclusion.  It must be one or the other.  Logic, by definition, by concept, must be linear.