The power of specification

Avoid the pitfalls to gain the prize.

From Is Dembski’s Explanatory Filter the Most Widely Used Theory Ever?, by Eric Holloway

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William Dembski created quite a stir in the world of information theory with his book The Design Inference. For the first time, he outlined a rigorous method for identifying design, which he called the explanatory filter. Since then many critics have claimed that Dembski’s proposed filter is without merit due to the lack of application in the couple of decades since its invention. But, are the critics right, or are they wrong—wrong in the way that a fish doesn’t recognize water because water is the very atmosphere of the fish’s existence?

Let us first remind ourselves of Dembski’s explanatory filter. His filter proceeds in three main steps.

  1. Eliminate events of large probability (necessity)
  2. Eliminate events of medium probability (chance)
  3. Specify the event of small probability with an independent knowledge source

The structure is short but dense. It can best be understood by revisiting a common argument between theists and atheists:

Theist: Look at all the very improbable biological structures. They cannot all have occurred by chance!

Atheist: A specific sequence of 100 coin flips is extraordinarily improbable; you’ll never see it again. But it happens.

Theist: Blimey, I’m stymied!

Atheist: Exactly, you have just fallen prey to the Texas sharpshooter fallacy:

You will get a chortle or two from Spurious Correlations, a web page devoted to graphically persuasive relationships among pairs of sets of entirely unrelated data. For example, you can see the graph of “US spending on science, space and technology” superimposed on that of “Suicides by hanging, strangulation and suffocation.” The staggering 99.79% overlap is a classic in correlation without causation.

Robert J. Marks, “Study shows, eating raisins causes plantar warts” at Mind Matters News

In other words, how do we know whether an unusual sequence or correlation is meaningful?

The theist has followed Dembski’s filter for the first two steps, but ignored the third (Specify the event of small probability with an independent knowledge source), which is the kicker. It is the third specification step that eliminates the sharpshooter fallacy. If our coin flipper sees a sequence of 100 heads, he is well within his right to say it did not occur by chance if he can bring an independent knowledge source to bear and he need not worry about the sharpshooter fallacy. This is the power of specification.

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