It's another Logical Fallacies Friday here on Blogosphere. You grab the loose basketball at center court. You're spun around by the point guard. You recover your balance and streak down the court, do a 360 windmill slam, toss up your hands in triumph. And then you realize that you threw the ball straight into your own basket. The logical equivalent of that is called "circular reasoning." This is where you assume the truth of what you're trying to prove while you’re trying to prove it. It's enough to make your head spin, and often does. If you find yourself getting dizzy in an argument, you or your opponent may be arguing in circles. The fallacy is called “ petitio principii” or "begging the question."
Here are a few examples just to get your head spinning:
"You can't go out on Wednesday night because you're only permitted to go out on Friday nights."
Do you get the feeling that wasn't much of an explanation?
"The reason I keep insisting that there was a relationship between Iraq and Saddam and al-Qaida is because there was a relationship between Iraq and al-Qaida." (George Bush)
They don't call it "spin" for nothing.
"There is no such thing as knowledge which cannot be carried into practice, for such knowledge is really no knowledge at all." Wang Shou-Jen, Record of Instructions
Huh?
Here’s an enlightened dialogue:
"Why?"
"Because!"
"Why because?"
"Because because!"
"Why because because?"
"Because I said so!"
That pretty much settles it, don't you think?
A classic, and very funny, exercise in circular reasoning is the little drama called "Kissing Hank's Ass". (If Mom is looking over your shoulder and is offended by colorful language, click on "Kissing Hank's Butt" for the PG-13 rated Sunday School version.) It’s written by a clever atheist who delights in spinning the bad logic of well-meaning Christians who come a’knocking at his door. Be forewarned. Quite a few Christians turn a sickly shade of grey when they read this dialogue or hear it performed because they recognize their own fallacy, which goes something like this:
"You should trust in Jesus."
"Why should I trust in Jesus?"
“Because I trust in Jesus.”
“Why do you trust in Jesus?”
"Because the Bible says so."
"Why should I believe the Bible?"
"Because it's true."
"How do I know the Bible's true?"
"Because the Bible says it's true."
That's why we don't begin with an inspired, inerrant Bible or our own believing, but with the virgin-born Jewish carpenter from Nazareth and His historic death and resurrection. You can prove from historic evidence that the Bible is historically reliable. But you can't prove from the Bible that the Bible is true, since that would presuppose the truth of the Bible before you proved it and will make you and your hearers very dizzy. Another way of saying this is that the authority of the Bible is established by the authority of Jesus who died and rose from the dead; the authority of Jesus is not established by the authority of the Bible. That's one reason you'll never see Lutherans referred to as "Bible-believing." We are Christ-believing, of whom the Bible bears reliable witness.
David Hume (1711-1776), the skeptical philosopher and logician of the Enlightenment, showed that the claim "The future will essentially be like the past" is circular reasoning. Why should the future be like the past? Because in the past, the future has always been like the past. I bring this up for a specific reason. The same David Hume who refuted the "back to the future" argument wrote this about miracles in the very same book:
“A miracle is a violation of the laws of nature; and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined.” David Hume - An Enquiry Concerning Human Understanding
He thought he'd slam-dunked Christianity’s belief in miracles. By now, you should be able to detect his petitio principii:
Laws of Nature are based in unalterable experience’
Unalterable experience is inviolate,
Therefore, the laws of nature are inviolate.
Miracles violate the Laws of nature,
Therefore, miracles are impossible.
In other words, miracles are impossible because miracles don't happen. Even the great ones fumble the ball once and a while.
The petitio principii often fools the person making the argument more than his or her opponent. You’re so passionate about your point, you fail to realize that you haven’t proven it, you just restated it. Politicians, pundits, huckster evangelists, and anyone trying to pull the wool over someone’s eyes may try to pass off a petitio principii like a counterfeit twenty dollar bill when they know they are empty handed in the evidence department.
To call the hand on a petitio principii, you need to show that the conclusion must be presumed to be true before you can accept the premise. Like my cat when she’s being playful, the tail she chases down and catches winds up being her own.
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