Design Arguments
If you ask someone why they believe in God, they are likely to appeal first to the apparent design of the universe. “Look around. How could this all be here by accident? Surely someone supremely wise and powerful made it this way.” The term design is used to mean apparent features such as regularity, order, purpose, constraints, fittedness. A design argument for the existence of God goes on to suggest that if such apparent features of the world cannot be explained by appealing to a physical process or another naturalistic explanation, then theism presents a better explanation.
Proponents of design arguments start at various points. Sometimes they begin with the order or regularity of the whole universe. Other arguments begin with a particular feature of the universe. Finally, other more recent proponents begin the apparent improbability of the universe being capable of sustaining life. From the starting point, design arguments move to show that the apparent design of the universe implies that it was designed by an intentional being, namely God.
Analogy to Artefacts
First, some arguments begin by noting the apparent order of the universe. The universe exhibits the kinds of order often expressible in mathematic theorems. It has repeated patterns and regular sequences. All of these apparent facts about the universe appear not to be random but the result of some intentional design. The appeal of these kinds of arguments is the intuition that order cannot happen by accident. What are the chances that the universe exhibits such an order if it is not the result of an intentional act of a divine agent?
Perhaps the most well-known design argument of this kind was produced by William Paley (1743-1805). Paley invited the reader to image taking a walk across a field. One might see a rock on the ground. The rock would be quite ordinary. It wouldn’t be out of place. Imagine, in contrast, if one comes across a watch on the ground. In contrast with the rock, the watch would appear to be out of place. What makes it appear out of place, says Paley, is that the watch is an artefact, an object intentionally designed and manufactured by an intentional agent. Now consider the universe. Is it more like the rock or the watch? Upon reflection, the universe is more like the watch. It has parts that all function as part of a whole. It appears much like a giant mechanism regulated in similarly precise fashion. Surely, just as one would enquire as to the maker of the watch, one would naturally want to know the maker of the universe
Paley’s argument relies on the analogy between the watch and the universe. To argue by analogy is to compare two entities and their attributes. The proponent catalogues the attributes that are the same for two entities and then moves to an additional attribute known to be an attribute of one of the entities and suggests that the other entity has that attribute as well. An argument by analogy is strengthened by appealing to the relevance, number and diversity of similarities between the analogues. It is weakened by appealing to a disanalogy, pointing out dissimilar attributes, and specificity in the conclusion.
Mind-World Fit
Second, some design arguments commence by noting a particular feature of the universe that appears designed. For example, consider ordinary human cognitive faculties. What explains the fact that human cognitive faculties are attuned to the world in such a way as to produce accurate perceptions and beliefs? If God designed both the world and our cognitive faculties, he would design such a fittedness. But if both the world and our cognitive faculties are the result of blind forces, then what grounds do we have to trust the deliverances of their interaction with one another?
For example, consider information conveying systems. Languages cannot convey meaning without an intentional, rational entity being involved. DNA offers an example of information conveyance within nature itself that would prove difficult to explain without appeal to an intentional mind encoding information in a formal language. In such an argument, the meaning of signs entails the presence of meaning prior to the encoding of meaning in symbols. This is evident in the arrangement of signs. If signs are arranged in order to express meaning, then some intentional being arranged them that way in order to express meaning.
An argument of this kind is given by Richard Taylor. He asks us to consider a train ride into Wales and encountering a selection of rocks spelling out, ‘British Railways welcomes you to Wales.’ Taylor argues that though one might suppose that those rocks had accidentally fallen in such a way, one cannot also hold that the sentence provides any evidence that one has entered Wales or that British Railways is welcoming anyone to anywhere. The same is true, he suggests, with our mental and perceptual faculties. One might suppose that they are the way they are by chance, but one cannot also hold that those faculties also provide good evidence for whatever beliefs they might produce. Thus, the best explanation for the arrangement of the rocks and the arrangement of our mental faculties is that they were arranged to provide evidence for beliefs—that the train rider is entering Wales and that I am looking at a computer screen.
Fine-Tuning
Finally, many recent design argument proponents begin from the observation that the universe is ‘fine-tuned.’ According to this kind of argument, design is seen as a set of physical constraints necessary for living organisms. Given the tiny probability that those constraints could occur by accident, the design proponent concludes that those constraints must have been set by a designer.
Fine tuning arguments display the apparently enormous variety of possibilities for how the universe could have been and that of these options which ones would support life. It turns out that the ways in which the universe must be in order to sustain life is comparatively tiny. For example, after the big bang, the universe ‘inflated’ at a rapid rate. Had the rate of inflation increased by as little as 1060, the universe would not have been capable of surviving.
Proponents of the argument show that there is a vast array of variables all of which must be tightly constrained for life to be possible. The proponent of the argument then asks: what are the chances of the universe that we actually have being the way it is—one that supports life—when there are so many ways it could have been? They then compare two explanations, theism and non-theism. Since the fine-tuning of the universe is probable under theism and highly improbable under atheism, fine-tuning provides strong evidence in favor of theism over atheism.
For an excellent discussion of the many kinds of design arguments, see J. P. Moreland, Scaling the Secular City: A Defense of Christianity. William Paley’s argument can be found online. Just search for “William Paley’s teleological argument full text.” For more on arguing from analogy, see Patrick Hurley, A Concise Introduction to Logic, chapter 9. Richard Taylor’s argument can be found in his Metaphysics, 110–115. Robin Collins is a foremost proponent of the fine tuning argument. You can find a good version of it in his chapter, “A Scientific Argument for the Existence of God” The Fine-Tuning Design Argument,” in Reason for the Hope Within edited by Michael Murray.