Central to the scientific method is a process for deciding between conflicting models of how the universe operates. It is very instructive to apply this process to the argument from design for the existence of a higher intelligence in the universe. The argument from design is commonly associated with William Paley (1743 – 1805) and for those who like big words, is also called as the teleological argument for God’s existence. A counter argument is given in Richard Dawkins’ book: The Blind Watch Maker. The basic argument from design is, however, much older than Paley; it goes back to the ancient Greeks. Needless to say, Dawkins’ book has failed to lay the argument to rest. If one checks the current state of the arguments on the topic, they typically are of the form: Anyone who does not recognize design in the universe is in denial, and the counter argument is: Those who see design in the universe are delusional. Needless to say, neither argument is particularly convincing. So what can the scientific method add to resolving the impasse? Quite a bit actually.
Let’s begin by looking at the actual form of the argument. It was stated succinctly by Cicero (106BCE – 43 BCE): When you see a sundial or a water-clock, you see that it tells the time by design and not by chance. How then can you imagine that the universe as a whole is devoid of purpose and intelligence, when it embraces everything, including these artifacts themselves and their artificers? This analogy was expanded upon, most famously, by Paley (quoted from the Wikipedia):
[S]uppose I found a watch upon the ground, and it should be inquired how the watch happened to be in that place, I should hardly think … that, for anything I knew, the watch might have always been there. Yet why should not this answer serve for the watch as well as for [a] stone [that happened to be lying on the ground]?… For this reason, and for no other; namely, that, if the different parts had been differently shaped from what they are, if a different size from what they are, or placed after any other manner, or in any order than that in which they are placed, either no motion at all would have been carried on in the machine, or none which would have answered the use that is now served by it.
So what about the watch and how do we know that it was designed? We begin with one of the mantras of this series of essays: The meaning is in the model. To understand the watch and its creation, our mind, either consciously or unconsciously, develops a model for its origin. The watch is deduced to have to been made by humans, not by non-human agencies, and humans do things by design. Thus, by a two-step process we arrive at design. Now, the watch is fairly obvious, but what about that pointed rock on the ground? Is it due to design or natural causes? Is it simply a broken rock or is it an arrow head? Here the question of design is strictly one of if it was made by humans or not. If the indications on the rock show signs of human manufacture it is considered due to design, and if not, then accident.
The typical theist would claim that the universe and everything in it is designed. Thus, we cannot do the comparison of something designed to something that was not designed; a technique that was useful in deciding if the watch was humanly designed or not. So how do we tell if something is designed or not? Use the methodology from science, of course.
In science, there are two distinct steps with any model: first the model must be constructed, and then it must be tested. Model construction is a creative activity and does rely on analogy and pattern recognition. Thus, in the initial stage, the argument from design is on good grounds. Now for the crux of the matter: the crucial test is neither how good the analogy is, nor how striking the apparent pattern, but rather if the argument from design passes the tests of parsimony and also makes successful predictions for observations. The scientific method defines three criteria for judging models: the successful description of past observations, the ability to make correct predictions for future observations, and simplicity. Being able to describe past observations is just the price to play the game, and with sufficient ingenuity, can usually be done. The definitive test of a scientific model is the ability to make predictions for novel phenomena. By predictions, I mean definite predictions that can be falsified. Not the kind of predictions made by Nostradamus that after the fact can be claimed to have been fulfilled, but rather definite predictions that can be tested, like it will rain tomorrow at TRIUMF between 3:00 and 4:00 pm.
Finally, there is simplicity. Yes, there is always simplicity or parsimony. By simplicity, I mean the elimination of assumptions that do not help the model make predictions. Today, common descent for living things is pretty much established and is mainly challenged by gross violations of the simplicity principle. A prime example is the omphalos hypothesis of Phillip Gosse (1810 – 1888). He stated that the world was created six thousand years ago, but in a manner that cannot be distinguished from one that is much older. As pointed out in a previous essay, that hypothesis can only be eliminated by an appeal to parsimony. As for design, natural selection is one way of generating the design of living things without the need for external intelligence and, at least at the small scale, natural selection is observed to be happening. So, can an external intelligence as suggested by the argument from design, or the idea of intelligent design, add anything useful to this? Or can they both be eliminated, like the omphalos hypothesis, by the appeal to parsimony? The challenge to the proponents of the argument from design (and similarly for intelligent design) is to make precise testable predictions, not postdictions, that distinguish it from natural selection.
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 This post was partly motivated by such an exchange on Huffington Post.