An Introduction to Design Arguments, by Benjamin C. Jantzen

The argument from design for the existence of God has been around a long time—since Cicero in the first century, according to Benjamin Jantzen. Surprisingly, though, that leaves a couple of millennia of recorded history before Cicero—including all of Old Testament times—when no one appealed to apparent design in nature as an argument for the existence of God. Jantzen’s explanation for this is interesting: the first step in the development of design arguments is the recognition that there are unintelligent, inanimate causes.

In the ancient world nature was understood to be full of gods who were causal agents. There really was no distinction between natural and supernatural causation. Arguing from design in that environment would be like arguing with a fish for the existence of water. The ancients were surrounded by what they took to be the action of intelligent agents—from the rising of the sun, to the production of crops, to sickness and health. Before design arguments could even be considered, “someone had to raise the serious possibility that other causes of structure and change are operative in the world besides those we identify with life and mind.” Once natural causes become an option for explaining what we see, we had to ask whether those natural causes were responsible, or whether something beyond nature had to intervene. Design arguments depend on our ability to discern the difference.

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Most of us have a powerful intuition that various parts of the natural world show purpose, order, or providence. The trick, though, is to take that intuition and transform it into rigorous and compelling arguments. Benjamin Jantzen has done a marvelous job at analyzing the many attempts at such transformations. He is consistently able to drill down into the arguments and clearly reveal the key, often unstated, claims on which the success of an argument depends.

Jantzen organizes all of the design arguments through the ages into four basic types: arguments from order, purpose, providence, and analogy. All appeal to empirical evidence that suggests some sort of divine agency, but it is helpful to see their nuances clearly distinguished so we don’t fall prey to common misconceptions and misrepresentations. For example, it is widely reported that David Hume convincingly refuted the design argument in his Dialogues Concerning Natural Religion before William Paley wrote his classic formulation of a design argument. But Hume’s criticisms are famously against the analogical form of the design argument, while Paley’s version is best understood as an argument from purpose. Objections can still be made against Paley, but they are different from Hume’s objections.

In the first half of the book, Jantzen outlines many other interesting treatments of design arguments throughout history. But for many readers the most important and helpful part will be the large section on the contemporary intelligent design movement. It is a curious omission that there is no treatment at all of intelligent design’s currently most prominent figure, Stephen Meyer. His books Signature in the Cell (2009) and Darwin’s Doubt (2013) have become the leading edge of the movement. I suspect that Meyer’s work came along too late in the development of Jantzen’s book, which is clearly the fruit of many years of engagement with the material. It is regrettable, though, that what aims to be a comprehensive treatment of design arguments does not include the most important contemporary exemplar.

Previously the most prominent figure in the ID movement was Michael Behe. In his argument for irreducible complexity Behe appeals to natural structures that have many different parts and perform a certain task, like causing the blood to clot or propelling bacteria. He argues that it wouldn’t be possible to complete such a task without all the parts functioning together; therefore evolution, which works through gradual accretions, can’t account for such structures. So, Behe claims, there must be a supernatural designer who brought about these irreducibly complex structures.

The idea of irreducible complexity has had remarkable intuitive staying power among ID followers, but when the intuition is converted into an argument, it has considerably less persuasive force. First, almost all biologists think Behe is wrong about the specific examples of structures that he says are unexplainable by evolution. But most people’s intuition is guided by a caricature of how evolution works. They think that each structure or trait develops in isolation. In reality, natural selection operates on combinations of traits, not merely on isolated structures. Half-developed wings won’t help an insect fly, but they might help it do other things that contribute to its survival, like skim across the surface of water. Contrary to the ID claim about irreducible complexity, you don’t have to get the whole thing at once.

Of course, there are many things we don’t yet understand about evolutionary history. So if Behe were to produce an example of an irreducibly complex structure for which scientists had no compelling evolutionary account, would that be enough to generate the conclusion that it must have been designed? No, says Jantzen; there is another problem with the argument. When Behe claims that irreducible complexity is best explained by a designer, Jantzen reminds us that best is a comparative term and can only mean “best among the known explanations.” If history is any guide here, we should expect that we don’t yet know all the possible explanations, so Behe’s claim is considerably weakened.

Jantzen treats other forms of contemporary design arguments with equal deftness. In his estimation, none of these reaches the level of being “entirely compelling.” He thinks the fine-tuning arguments have the most going for them, but ultimately their success depends on abstruse metaphysical arguments about the nature of law, explanation, and possible worlds about which there is no consensus. The arguments are much trickier than the simple intuition of design we have when we see beautifully ordered and purposeful natural objects. Time and again I found myself agreeing with the criticisms Jantzen offered, and by the end I almost felt sorry for design advocates as the soft underbelly of their arguments was exposed.

However, I wish that Jantzen had stepped back from examining specific arguments and reflected more systematically on the enterprise of using science to prove the existence of God. Perhaps this is the real problem with design arguments. Science became so spectacularly successful during the 17th and 18th centuries by limiting itself to what we today call natural causes. Recognizing impersonal causes was the necessary first step for design arguments to get off the ground. But now the arguments that attempt to draw theological conclusions from scientific premises are confusing the boundaries that scientists have come to respect.

Of course, there are naturalists who assert that scientific inquiry exhausts all of reality and that the failure of scientific methods to detect God shows there is no God. But there are plenty of first-rate scientists who recognize that the natural sciences are the wrong kind of tool for detecting God and who draw no theological conclusions from the failure of scientific proofs. If a fishing crew uses a net with two-inch holes to trawl a lake and only catches fish that are larger than two inches, they don’t conclude that there are no fish smaller than two inches in the lake.

The ID camp does a disservice to the predominantly conservative Christian community to which it appeals by conditioning that community to mistrust science. Its arguments depend on accepted, settled science getting things wrong. So now an alarming number of Christians also reject the conclusions of scientific experts on climate change and vaccines. Of course experts make mistakes. The trick is to realize that they can be trustworthy as well as fallible.

Instead of attempting to exploit the insufficiencies of science to prove the existence of God, perhaps the more constructive approach is to look at the natural world in the light of faith. We see God’s hand throughout the created order not because science can’t explain nature, but because it can. The De­signer’s mark is not in systems that don’t work quite right and need tinkering; those are signs of imperfection. Scientists—whether Christians or not—who uncover the inner workings of nature are the ones who learn something of the mind of God.