Last week, I provided a primer on the general approach to design detection. My aim was to help readers in appreciating the logic behind the new expanded second edition of The Design Inference, by William Dembski and Winston Ewert. Here, I will summarize key insights the book presents.
The central idea presented in the first edition of The Design Inference is that design detection involves identifying patterns that are both highly improbable and specified. A major question raised by critics of the first edition is the meaning of the terms specified and specification. In other words, what exactly makes a pattern specified or special? In many contexts, the answer is simple. A half-eaten doughnut filled with arsenic next to a dead body would be a highly special doughnut, strongly suggesting that the death was not due to natural causes but due to design.
As a less grim example, being dealt four poker hands that were all royal flushes would be a very rare and special pattern, pointing to someone cheating. Design detection in this example is easy because the category royal flush was already defined (aka prespecified) by the rules of the game. The situation is more challenging in situations where categories of outcomes are not so clearly defined.
Here lies the genius behind the new edition. Dembski and Ewert define a specification as a description that requires few words. The description must also apply to only a small proportion of possible outcomes, so the probability of any outcome falling within the specification must be sufficiently small. A pattern that is both identifiable by a short description and highly improbable is almost certainly designed.
Poker and Alien Faces
Going back to the poker example, the four hands I mentioned could be described by the three words four royal flushes, and the probability of four honestly dealt hands falling within this specification is very small, less than 1 chance in 100 billion trillion. The short description and very low probability entail design, as you would immediately recognize if you were ever dealt such a special set of hands in a single night of poker.
In contrast, describing four typical hands of five cards would require a very long description, such as the following:
Two of diamonds, pair of threes, four of spades, three sevens, nine of hearts, three tens, two jacks, three queens, king of clubs, three aces.
The probability of four hands falling within this description is low, but the description length is very long. Many sets of 20 cards would fall within a description of that length. The low probability is offset by the large number of descriptions that are long, so the probability of being dealt four hands with such a long description is not sufficiently low to conclude design.
Conversely, one could label a generic set of 20 cards with the description random cards. The description is now short, but the probability is very high of a set of cards falling within this description. The short description is offset by the high probability. Similarly, the famous face on Mars can be described by the two words fuzzy face. Here again, the description length is short, but the probability of a photograph of the surface of a barren planet matching a face at least as well as the Mars photo is sufficiently high to occur by chance.
The Underlying Logic
The underlying logic of Dembski and Ewert’s methodology is profound. As I mentioned in my earlier article, identifying design requires something being assigned by a mind a special significance. A short description meets this criterion since societies assign words or short phrases to that which they designate as special.
As a final illustration from the second edition, in the movie The Empire Strikes Back, Darth Vader declares to Luke Skywalker one of the most iconic lines in movie history: “I am your father.”
Darth Vader could be specified by the single word father. The relationship of father was designated by the Galactic Empire, as in our society, as a very special relationship. Relatively few other people could be specified by such a short description. Consequently, Luke knew his meeting Vader was not by chance but by design, partly facilitated by the dark side of the force.
In stark contrast, Dark Helmet in the movie Spaceballs tells Lonestar something far less profound: “I am your father’s brother’s nephew’s cousin’s former roommate.”
The fact that Dark Helmet required such a lengthy description to specify himself reflects the fact that their relationship carried no significant meaning. Such a generic relationship could have occurred purely by chance.
In the final chapter of the book, the authors describe how their methodology could best be applied to biology. They recommended identifying essential biological systems that demonstrate high levels of irreducible complexity. In addition, target systems should be composed of components where upper bounds to the probability of their originating from chance and natural processes could be estimated. Several biological systems such as DNA replication, protein translation, and energy production fall into this category.