Why Darwin Matters_ The Case Against Intelligent Design - Michael Shermer [31]
Second, we perceive nature to be intelligently designed based on our experience of human artifacts. We know some human artifacts are intelligently designed because we have observed them being made and we have vast experience with human artificers. By contrast, we have no experience with a nonhuman intelligent designer, and no experience with a supernatural agent—outside of inferring that one exists by identifying the current gaps in our knowledge of apparently designed objects. The skeptical principle, Methodological Naturalism, or, no miracles allowed, refutes the inference to supernatural intelligent design. Not yet understanding how something was created naturally does not make it a supernatural creation.
Last, we must be cautious about inferring design because our experience with intelligently designed artifacts in our culture biases us to see intelligent design where none exists (for example, those Virgin Mary apparitions). Long before Darwin debunked the watchmaker argument, the Enlightenment philosopher Voltaire satirized this problem in his classic novel Candide, through the character Dr. Pangloss, a professor of “metaphysico-theology-cosmolonigology”: “’Tis demonstrated that things cannot be otherwise; for, since everything is made for an end, everything is necessarily for the best end. Observe that noses were made to wear spectacles; and so we have spectacles. Legs were visibly instituted to be breeched, and we have breeches.”20
Explanatory Filter: A tool for discriminating between natural design and intelligent design shows that only an Intelligent Designer can account for complex specified information and design.
Mathematician William Dembski has devised an “Explanatory Filter” through which intelligent design can be distinguished from natural design. Dembski asks, “When called to explain an event, object, or structure, we have a decision to make—are we going to attribute it to necessity, chance, or design?”21 If necessity (natural law) and chance (randomness) cannot explain the phenomenon, then design (intelligence) is the default answer. The filter operates in a three-step process:
1. Does natural law explain the design? If event E has a high probability, accept necessity as an explanation; otherwise move to the next step.
2. Does chance explain the design? If event E has an intermediate probability or E is not specified, then accept chance; otherwise move to the next step.
3. Does intelligent design explain the design? Having eliminated necessity and chance as the explanation for a highly specified but low probability event, accept design.22
The Explanatory Filter is a tool by which we can tell the difference between the naturally designed JFK rock formation and the intelligently designed Mount Rushmore rock formation: “I argue that the Explanatory Filter is a reliable criterion for detecting design,” Dembski explains. “Alternatively, I argue that the Explanatory Filter successfully avoids false positives. Thus, whenever the Explanatory Filter attributes design, it does so correctly.”23
But the Explanatory Filter assumes probabilities that cannot be determined in practice; it is nothing more than a thought experiment and cannot practically be used in science. Indeed, in order to eliminate all necessity and chance explanations assumes that we know all configurations of these explanations, which, of course, we do not. Even if we did, and rejected them all, the design inference does not follow. Design, as it is commonly defined by the Intelligent Design movement, means purposeful and intelligent creation, not simply the elimination of necessity and chance. In other words, design is not just a default conclusion when all else fails to explain. Design requires positive evidence, not the rejection of negative evidence. The Explanatory Filter cannot survive the scrutiny of two skeptical principles—the Burden of Proof and the Either-Or Fallacy.
In addition, even if positive evidence for design were presented, by the logic of the Explanatory Filter we should be able to apply the filter to the design’s designer.