Explanatory Filter

The Explanatory Filter is a "protocol" devised by intelligent design creationist William Dembski which purports to detect whether or not any entity (object, living thing, etc.) was designed by an intelligent agency. If such a protocol did exist, it would be a valuable addition to the set of scientific tools; sadly, Dembski's Explanatory Filter does not live up to its press releases.

Process
The Explanatory Filter operates by 'filtering out' everything which is not Design, and declaring whatever is left to be Design. As Dembski puts it:

Dembski explains:

Dembski notes that "exceeding improbability is by itself not enough to preclude something from happening by chance", although other creationists disagree. To explain how, except via improbability, we can determine design, Dembski writes:

Specifications would become Complex Specified Information in Dembski-speak.

"Examples"
Dembski provides several examples through which design is supposedly found.

Caputo
Dembski provides the example of Mochary v. Caputo (1985) to illustrate these points:

Copyright
One of the examples is

However, only designed objects can be copyrighted or patented, so copyright and patent offices do not detect design, but non-design, that is, plagiarism. But for Dembski, plagiarism counts as "intelligent design".

SETI
Another example is

Except that it isn't, according to the SETI Institute. As this article says, the SETI program does not actually search for anything "intelligent" (like a series of prime numbers, as Dembski, with inspiration from the movie "Contact", frequently claims), but for something as simple as a single sinusoidal wave that exhibits Doppler-shift - a possible indication that it might come from a planet rotating around itself or orbiting a star.

Attempted formal definition
Given an event E, let H be a "non-design" hypothesis that can explain E, then


 * 1) if P(E | H) is high, conclude regularity (law);
 * 2) if P(E | H) is medium, conclude chance;
 * 3) if P(E | H) is low, and there is a known simple specification for E, conclude design.

In the drop-out case, that is low probability and no known simple specification, the conclusion is chance.

Note that there is only mentioned one hypothesis (H) here, and Dembski usually only refers to one hypothesis, though occasionally he refers for "all relevant chance hypotheses", but then subsumes them into the one hypothesis H = {Hi}i.

Problems
The problem with this is that we cannot filter out everything which is not Design!

Argument from ignorance
Many "design inferences" are actually wrong, though they may be reasonable relative to the general knowledge of their own time. If used on an entity that is the result of processes not currently known, or of a currently-unknown concatenation of known processes, the Filter would tell us that that entity is Designed. As a practical matter, the Filter cannot actually be successfully applied by non-omniscients. Thus, it is an excellent example of the Sherlock Holmes Fallacy.

By way of demonstration, consider that historically, nearly everything has been considered the direct result of an intelligent agency before people understood it. Storms were caused by Thunder gods. How could water get up into the sky without divine help? How could it gather? What else could explain lightning? But it doesn't end there. How could the planets stay up without angels? What could explain gems or metal veins being embedded inside other rocks? What else but angry gods could cause plagues? The list is endless. And the list is, for every currently known phenomenon, a long line of errors. That is, Dembski's filter has been applied repeatedly throughout history and been wrong every single time. Historically, science has always begun when arguments from ignorance like Dembski's are rejected and stymied when they are proclaimed science.

Dembski, aware of these flaws, wrote:

Given this, it seems premature to conclude anything based on the Filter, unless we accept that our ignorance is a valid reason to do anything. Rather than a design conclusion, we may be better off saying that we don't know yet - further research is needed. In a court case, new evidence can turn the tide.

Lack of application
It is worth noting that in spite of IDists' claims that Dembski's Filter demonstrates that life was Designed, nobody has ever actually applied the Filter to any life-form, nor yet even to any identifiable aspect nor feature of any life form.

One-pass?
In the Caputo case, there were two different chance hypotheses, one that Caputo was in good faith, but used an unreliable randomization process, and one that Caputo, as he claimed, used a reliable randomization process. To determine design, we would need to rerun the filter over and over again, until all chance hypotheses had been removed. Saying that they are part of the same chance hypothesis may be stretching the notion of a hypothesis a bit too much.

Clarity of "design"
It's unclear what "design" really means. Dembski provides an example of electoral fraud, intellectual property fraud, and electronic transmissions as times in which the Explanatory Filter applied, but they certainly don't all use the same definition of "design" or "intelligent".