We see here the ingredients of any argument from design. A design argument, like a
cosmological argument, begins with a contingent existential fact, but, unlike a
cosmological argument, one that has a valuable status, such as that there exists natural
beauty, widespread lawlike regularity, and the like. It must be stressed that the fact about
design is a morally desirable one. Otherwise, nothing could be inferred about the
goodness, as contrasted with the intelligence and power, of the person who brings about
the fact. Moreover, if the design explanation is to be satisfactory, the existential fact
should be one that an intelligent person would not be too unlikely to desire: if we have a
group of stones strewn about apparently at random, we would not expect that an
intelligent person desired precisely that combination.
To avoid the charge of begging the question, the premise in a design argument that
reports the existence of some natural object or process that displays design or purpose
must not be taken in such a way that it immediately entails that there exists a designer or
purposer, for that would bring on a justified charge of begging the question from the
opponent of the argument. Rather, it must be taken to mean that there exists a natural
object or process that has an apparent design, purpose, or function, leaving it an open
question as to what sort of a cause, if any, there is of this apparent design. It is then
inferred that the item was in fact designed by an intelligent agent. To be God, the
designer would have to be among other things all-good. The moral qualities of the
designer would have to be inferred from known facts about the world. Many items
showing apparent design have been adduced, including biological mechanisms, the
apparent fine-tuning of the constants in the laws of nature, the regularity of the laws of
nature, altruism, consciousness, the existence of various natural kinds of animals, the
purposefulness of things in nature, and even miracles—this last, special case being
discussed in another chapter in this book. The inference in the argument is typically
nondeductive: the argument may involve analogy to artifacts of human design, as in
end p.128
Paley's case, or an inductive appeal to data that things showing a certain kind of
complexity are in fact designed by intelligent agents, or inference to best explanation, or
some other way of recognizing the marks of intelligent design.
In his Dialogues Concerning Natural Religion, David Hume (1980) considers a
teleological argument in which it is inferred that the universe as a whole resembles
human artifice, and therefore also has an intelligent designer, though a proportionately
greater one. Hume objects that there is a serious disanalogy between the whole universe
and human artifice. Any disanalogy weakens an analogical argument. But to do serious
damage, the disanalogy needs to show a difference in those respects of the supposedly
analogous cases that are essential to the argument. What is essential to the teleological
argument, its defender will insist, is that both watches and the universe, or some subset of
it such as a biological organism, show a marvelously complex interrelation of parts, and
Hume does not attack the similarity in this respect.
However, Hume insists that what is essential to inferring the designer of things like
watches and houses is that we have seen things of this sort with this kind of complexity
and on this scale made by human beings, whereas we could not have seen universes being
designed since by definition the universe is unique. If we had not seen mechanisms made