BeanQuest

June 14, 2007

The Bible on Pi

Filed under: pedantry, pointlessness — Brian @ 7:36 pm

I found this post today in the WordPress Dashboard, making what at first almost appears to be a Good Argument that the Bible Is Wrong In This One Case Someone Pointed Out Here in I Kings 7:23, which says,

He made the Sea of cast metal, circular in shape, measuring ten cubits from rim to rim and five cubits high. It took a line of thirty cubits to measure around it.

The argument is that the Bible says pi equals “3. Also known as 3.00 or 3.0.” Well, 30 divided by 10 is 3, so it sounds like he’s got a point. Pi never ends, so if you say “it’s 3,” you’re really kind of wrong.

But you’re still wrong if you say it’s 3.14159. There is no string of numbers you can point to and say, “that’s pi!” and be correct. Even if the Bible used digits instead of words, here, there is no way it (or any other text) could state pi “correctly.” Sure, you can state it with more digits, and be less wrong. But it is not possible to state pi with any number of digits and be correct.

But his argument immediately goes off the rails in another direction, too. “3.00” is not at all the same thing as “3”. “3” could be anything from “2.50” through “3.49.”

In math, you cannot get a result that’s more precise than its least precise input. Said another way, the maximum allowable precision in an output is equal to the lowest number of significant digits in any of the inputs. And “ten” and “thirty” are the only inputs, and they each have one significant digit. So the output cannot have more than one significant digit.

And pi – to one significant digit – is three. That is, 3. Not 3.0, nor 3.00.

So the Bible implies that pi, to one significant digit, is 3. Which it empirically is.

To be clear, I’m nothing close to a Biblical scholar. But you can spot the holes in this “scientific” argument 1.609344 kilometers away.

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7 Comments »

  1. You’re absolutely right, Brian, and seeing people spending quality time concocting absurd arguments like this to refute the Bible’s infallibility is, well, annoying at best.

    Comment by gwynne — June 16, 2007 @ 2:08 pm

  2. Yes. I like substantive discussion. Particulary with people who disagree with me.

    But this one’s just a poor argument all around. It only goes somewhere if you don’t allow yourself to think about it. Which is ironic, given the subject of the argument. And not in a good way.

    Comment by Brian — June 16, 2007 @ 6:49 pm

  3. Actually, the issue is even less precise than you describe. Given that in Biblical times, a cubit was defined as the length from a man’s elbow to his extended fingertip, there’s no way that any given cubit would be equal to any other cubit – even for the same man – to the same level of precision that those who argue about pi have in mind.

    Comment by Eric — June 17, 2007 @ 9:51 pm

  4. I hadn’t thought about how it would be measured. Good point, Eric.

    Even a perfectly-calibrated measuring stick/tape/ruler won’t save you from small errors if you have to lay it end-to-end several times to make your measurement.

    Comment by Brian — June 18, 2007 @ 5:45 am

  5. i cant write to well i flunked 5X in school but i can do math. so i’ll make it short. the bible is giving instructing with demantions on how to make a big pot, look at it that way. the bible is correct. you dont have to streach or fudge the instructions. ten cubits is outside diamiter 30 cubits is inside circumfance and a hand (like in horses) is the thickness of the metal wall of the pot. check the radius of a 10 cubit circle and a circle w/a 30 cubit circumfrance the diffrence is hand or 4″ . PS. a bath of water (womans work) is about 11 liters, one in each hand, my wife was a water girl…….jim

    Comment by jim whitley — August 1, 2007 @ 3:55 pm

  6. I can see where you’re coming from, too Jim.

    I’m not sure I buy a pot with 4″ thick walls, but the point, here, is that there are so many ways to refute this argument, the only way to believe it is to pre-believe it and ignore any contrarian explanations.

    Comment by Brian — August 1, 2007 @ 4:58 pm

  7. very interesting, but I don’t agree with you
    Idetrorce

    Comment by Idetrorce — December 16, 2007 @ 2:32 am


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