Periscope Depth

ten thousand years ago, crawling on the floor

Three anecdotes:

  1. Driving to work the other day, I saw a car at the light ahead of me with the license plate TLW 862.

    I thought nothing of it.

  2. Driving to work the other day, I saw a car at the light ahead of me with the license plate JEP 401.

    “Hey,” I thought, “those are my initials! And that’s my birthday! Why, the odds of that happening by chance are … over one in seventeen million! That’s too improbable to have happened by chance! That license plate must have been made just for me.”

  3. While trying to reconcile the inescapable fact of the human race’s evolutionary origins, creationists have been known to say, “The probability of the chance formation of a hypothetical functional ‘simple’ cell, given all the ingredients, is acknowledged to be worse than 1 in 10^57800.” That’s too improbable to have happened by chance! Therefore, the Universe must have been made just for me.

The difference between #1 and #2 illustrates the error shared by #2 and #3.

I owe the license plate analogy to Richard Feynman, who wasn’t talking about evolution at the time. However, he did make a point about resisting the temptation to let the “specialness” of the data bias your conclusions. Just because the data means something personally important to you does not let you reason backward to a theory that would neatly justify it.

If I see a license plate that’s a random jumble of letters and numbers, I make no associations. If I see a license plate that’s a random jumble of letters and numbers that remind me of my name and birthday, I recognize that. My mind forms an association. The data now has special significance to me. If I live in a uniquely paranoid world, I might presume that license plate was made just for me. Perhaps someone infiltrated the license plate printing press.

If I live on a planet that’s a sea of unthinking protoplasm, I don’t assign it any significance1. But if I live on a planet that’s teeming with decision-making vertebrates, of which I happen to be one, I assign it a great deal of significance. My mind forms an association. The data now has a special importance to me. If I live in a uniquely paranoid world, I might presume that the world was made just for me. Perhaps someone lives in the clouds and makes elephants out of clay.

I could spend days talking about the problems with the creationist argument that the cell, or DNA, or the brain, have “too much complexity to have evolved by chance.”2 But the chief problem comes from a skipped premise. The syllogism goes as follows:

  • The odds of the human species evolving by chance are one in a squillion.3
  • Therefore, God made us.

Seriously, that’s it. What’s the second premise? “One in a squillion’s just too big to ever happen?” Says who? If we can conceive the number “one in a squillion” – if we can do the operations to write it down on paper, and it’s not an irrational imaginary number like the square root of -1 – then who’s to say the universe can’t contain it?

This illustrates the logical fallacy of petitio principii, also known as “assuming to be true the conclusion that you’re trying to prove” or “begging the question.” Creationists presume a specialness to the datum of human existence, then reason backward from there. In so doing, they skip a premise, in the hopes that once the numbers get too big to think about we’ll just stop paying attention. But logic doesn’t work that way. Neither does the universe.

Creationists don’t have a monopoly on this error. I just have the most fun pointing theirs out.

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1 Hell, I don’t assign anything any significance – I’m just a prokaryote!

2 Briefly: biologists don’t assert that “humans evolved by chance,” because the forces of natural selection, sexual selection, genetic drift, etc. are not “chance,” in fact they follow some pretty orderly principles, maybe you’d like to read about them sometime in a 9th-grade textbook; also, it’s ridiculous to speak of the state of the world as a one-in-a-squillion outcome, as that supposes that the universe is a die with a squillion other faces, or a test that’s been run a squillion other times, which I have no problem asserting but doesn’t come from the Intelligent Design handbook; also, what is “too much” complexity?; also, humans did not spring onto the scene as full homo sapiens, but rather descended from an enormous daisy chain of species, many of which have odds – using ridiculous creationist logic – of much less than one in a squillion of showing up; also, you’re stupid.

3 I have never heard the same number quoted on any two creationist websites, unless they reference each other. I know it’s a bullshit number anyway – they just start multiplying things like the number of proteins in a DNA strand until they get an impressively large number and then stare at it slack-jawed – but I’d like it to at least be consistent bullshit. Could you rubes get your act together? Have a conference call or something.

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