Design Arguments for the Existence of God

Design arguments are empirical arguments for the existence of God. These arguments typically,

though not always, proceed by attempting to identify various empirical features of the world that

constitute evidence of intelligent design and inferring God’s existence as the best explanation for

these features. Since the concepts of design and purpose are closely related, design arguments are

also known as teleological arguments, which incorporate “telos,” the Greek word for “goal” or

“purpose.”

Design arguments typically consist of (1) a premise that asserts that the material universe

exhibits some empirical property F; (2) a premise (or sub-argument) that asserts (or concludes)

that F is persuasive evidence of intelligent design or purpose; and (3) a premise (or sub-

argument) that asserts (or concludes) that the best or most probable explanation for the fact that

the material universe exhibits F is that there exists an intelligent designer who intentionally

brought it about that the material universe exists and exhibits F.

There are a number of classic and contemporary versions of the argument from design. This

article will cover seven different ones. Among the classical versions are: (1) the “Fifth Way” of

St. Thomas Aquinas; (2) the argument from simple analogy; (3) Paley’s watchmaker argument;

and (4) the argument from guided evolution. The more contemporary versions include: (5) the

argument from irreducible biochemical complexity; (6) the argument from biological

information; and (7) the fine-tuning argument.

1. The Classical Versions of the Design Argument

a. Scriptural Roots and Aquinas’s Fifth Way

The scriptures of each of the major classically theistic religions contain language that suggests

that there is evidence of divine design in the world. Psalms 19:1 of the Old Testament, scripture

to both Judaism and Christianity, states that “The heavens declare the glory of God; and the

firmament sheweth his handy work.” Similarly, Romans 1:19-21 of the New Testament states:

For what can be known about God is plain to them, because God has shown it to them. Ever

since the creation of the world his eternal power and divine nature, invisible though they are,

have been understood and seen through the things he has made. So they are without excuse.

Further, Koran 31:20 asks “Do you not see that Allah has made what is in the heavens and what

is in the earth subservient to you, and made complete to you His favors outwardly and

inwardly?” While these verses do not specifically indicate which properties or features of the

world is evidence of God’s intelligent nature, each presupposes that the world exhibits such

features and that they are readily discernable to a reasonably conscientious agent.

Perhaps the earliest philosophically rigorous version of the design argument owes to St. Thomas

Aquinas. According to Aquinas’s Fifth Way:

We see that things which lack knowledge, such as natural bodies, act for an end, and this is

evident from their acting always, or nearly always, in the same way, so as to obtain the best

result. Hence it is plain that they achieve their end, not fortuitously, but designedly. Now

whatever lacks knowledge cannot move towards an end, unless it be directed by some being

endowed with knowledge and intelligence; as the arrow is directed by the archer. Therefore some

intelligent being exists by whom all natural things are directed to their end; and this being we

call God (Aquinas, Summa Theologica, Article 3, and Question 2).

It is worth noting that Aquinas’s version of the argument relies on a very strong claim about the

explanation for ends and processes: the existence of any end-directed system or process can be

explained, as a logical matter, only by the existence of an intelligent being who directs that

system or process towards its end. Since the operations of all natural bodies, on Aquinas’s view,

are directed towards some specific end that conduces to, at the very least, the preservation of the

object, these operations can be explained only by the existence of an intelligent being.

Accordingly, the empirical fact that the operations of natural objects are directed towards ends

shows that an intelligent Deity exists.

This crucial claim, however, seems to be refuted by the mere possibility of an evolutionary

explanation. If a Darwinian explanation is even coherent (that is, non-contradictory, as opposed

to true), then it provides a logically possible explanation for how the end-directedness of the

operations of living beings in this world might have come about. According to this explanation,

such operations evolve through a process by which random genetic mutations are naturally

selected for their adaptive value; organisms that have evolved some system that performs a

fitness-enhancing operation are more likely to survive and leave offspring, other things being

equal, than organisms that have not evolved such systems. If this explanation is possibly true, it

shows that Aquinas is wrong in thinking that “whatever lacks knowledge cannot move towards

an end, unless it be directed by some being endowed with knowledge and intelligence.”

b. The Argument from Simple Analogy

The next important version of the design argument came in the 17th and 18th Centuries.

Pursuing a strategy that has been adopted by the contemporary intelligent design movement,

John Ray, Richard Bentley, and William Derham drew on scientific discoveries of the 16th and

17th Century to argue for the existence of an intelligent Deity. William Derham, for example,

saw evidence of intelligent design in the vision of birds, the drum of the ear, the eye-socket, and

the digestive system. Richard Bentley saw evidence of intelligent design in Newton’s discovery

of the law of gravitation. It is noteworthy that each of these thinkers attempted to give

scientifically-based arguments for the existence of God.

David Hume is the most famous critic of these arguments. In Part II of his famous Dialogues

Concerning Natural Religion, Hume formulates the argument as follows:

Look round the world: contemplate the whole and every part of it: you will find it to be nothing

but one great machine, subdivided into an infinite number of lesser machines, which again admit

of subdivisions to a degree beyond what human senses and faculties can trace and explain. All

these various machines, and even their most minute parts, are adjusted to each other with an

accuracy which ravishes into admiration all men who have ever contemplated them. The curious

adapting of means to ends, throughout all nature, resembles exactly, though it much exceeds, the

productions of human contrivance; of human designs, thought, wisdom, and intelligence. Since,

therefore, the effects resemble each other, we are led to infer, by all the rules of analogy, that the

causes also resemble; and that the Author of Nature is somewhat similar to the mind of man,

though possessed of much larger faculties, proportioned to the grandeur of the work which he

has executed. By this argument a posteriori, and by this argument alone, do we prove at once the

existence of a Deity, and his similarity to human mind and intelligence?

Since the world, on this analysis, is closely analogous to the most intricate artifacts produced by

human beings, we can infer “by all the rules of analogy” the existence of an intelligent designer

who created the world. Just as the watch has a watchmaker, then, the universe has a universe-

maker.

As expressed in this passage, then, the argument is a straightforward argument from analogy

with the following structure:

1. The material universe resembles the intelligent productions of human beings in that it

exhibits design.

2. The design in any human artifact is the effect of having been made by an intelligent

being.

3. Like effects have like causes.

4. Therefore, the design in the material universe is the effect of having been made by an

intelligent creator.

Hume criticizes the argument on two main grounds. First, Hume rejects the analogy between the

material universe and any particular human artifact. As Hume states the relevant rule of analogy,

“wherever you depart in the least, from the similarity of the cases, you diminish proportionably

the evidence; and may at last bring it to a very weak analogy, which is confessedly liable to error

and uncertainty” (Hume, Dialogues, Part II). Hume then goes on to argue that the cases are

simply too dissimilar to support an inference that they are like effects having like causes:

Since the analogy fails, Hume argues that we would need to have experience with the creation of

material worlds in order to justify any a posteriori claims about the causes of any particular

material world; since we obviously lack such experience, we lack adequate justification for the

claim that the material universe has an intelligent cause.

Second, Hume argues that, even if the resemblance between the material universe and human

artifacts justified thinking they have similar causes; it would not justify thinking that an all-

perfect God exists and created the world. For example, there is nothing in the argument that

would warrant the inference that the creator of the universe is perfectly intelligent or perfectly

good. Indeed, Hume argues that there is nothing there that would justify thinking even that there

is just one deity: “what shadow of an argument… can you produce from your hypothesis to

prove the unity of the Deity? A great number of men join in building a house or ship, in rearing a

city, in framing a commonwealth; why may not several deities combine in contriving and

framing a world” (Hume Dialogues, Part V)?

c. Paley’s Watchmaker Argument

Though often confused with the argument from simple analogy, the watchmaker argument from

William Paley is a more sophisticated design argument that attempts to avoid Hume’s objection

to the analogy between worlds and artifacts. Instead of simply asserting a similarity between the

material world and some human artifact, Paley’s argument proceeds by identifying what he takes

to be a reliable indicator of intelligent design:

There are thus two features of a watch that reliably indicate that it is the result of an intelligent

design. First, it performs some function that an intelligent agent would regard as valuable; the

fact that the watch performs the function of keeping time is something that has value to an

intelligent agent. Second, the watch could not perform this function if its parts and mechanisms

were differently sized or arranged; the fact that the ability of a watch to keep time depends on the

precise shape, size, and arrangement of its parts suggests that the watch has these characteristics

because some intelligent agency designed it to these specifications. Taken together, these two

characteristics endow the watch with a functional complexity that reliably distinguishes objects

that have intelligent designers from objects that do not.

Paley then goes on to argue that the material universe exhibits the same kind of functional

complexity as a watch:

Every indicator of contrivance, every manifestation of design, which existed in the watch, exists

in the works of nature; with the difference, on the side of nature, of being greater and more, and

that in a degree which exceeds all computation. I mean that the contrivances of nature surpass

the contrivances of art, in the complexity, subtitle, and curiosity of the mechanism; and still

more, if possible, do they go beyond them in number and variety; yet in a multitude of cases, are

not less evidently mechanical, not less evidently contrivances, not less evidently accommodated

to their end, or suited to their office, than are the most perfect productions of human ingenuity

(Paley 1867, 13).

Paley’s watchmaker argument is clearly not vulnerable to Hume’s criticism that the works of

nature and human artifacts are too dissimilar to infer that they are like effects having like causes.

Paley’s argument, unlike arguments from analogy, does not depend on a premise asserting a

general resemblance between the objects of comparison. What matters for Paley’s argument is

that works of nature and human artifacts have a particular property that reliably indicates design.

Regardless of how dissimilar any particular natural object might otherwise be from a watch, both

objects exhibit the sort of functional complexity that warrants an inference that it was made by

an intelligent designer.

Paley’s version of the argument, however, is generally thought to have been refuted by Charles

Darwin’s competing explanation for complex organisms. In The Origin of the Species, Darwin

argued that more complex biological organisms evolved gradually over millions of years from

simpler organisms through a process of natural selection. As Julian Huxley describes the logic of

this process:

The evolutionary process results immediately and automatically from the basic property of living

matter—that of self-copying, but with occasional errors. Self-copying leads to multiplication and

competition; the errors in self-copying are what we call mutations, and mutations will inevitably

confer different degrees of biological advantage or disadvantage on their possessors. The

consequence will be differential reproduction down the generations—in other words, natural

selection (Huxley 1953, 4).

Over time, the replication of genetic material in an organism results in mutations that give rise to

new traits in the organism’s offspring. Sometimes these new traits are so unfavorable to a being’s

survival prospects that beings with the traits die off; but sometimes these new traits enable the

possessors to survive conditions that kill off beings without them. If the trait is sufficiently

favorable, only members of the species with the trait will survive. By this natural process,

functionally complex organisms gradually evolve over millions of years from primordially

simple organisms.

The problem with Paley’s watchmaker argument, as Dawkins explains it, is that it falsely

assumes that all of the other possible competing explanations are sufficiently improbable to

warrant an inference of design. As is readily evident from Huxley’s description of the process,

Darwinian evolution is a cumulative-step selection method that closely resembles in general

structure the second computer program. The result is that the probability of evolving functionally

complex organisms capable of surviving a wide variety of conditions is increased to such an

extent that it exceeds the probability of the design explanation.

d. Guided Evolution

While many theists are creationists who accept the occurrence of “microevolution” (that is,

evolution that occurs within a species, such as the evolution of penicillin-resistant bacteria) but

deny the occurrence of “macroevolution” (that is, one species evolving from a distinct species),

some theists accept the theory of evolution as consistent with theism and with their own

denominational religious commitments. Such thinkers, however, frequently maintain that the

existence of God is needed to explain the purposive quality of the evolutionary process. Just as

the purposive quality of the cumulative-step computer program above is best explained by

intelligent design, so too the purposive quality of natural selection is best explained by intelligent

design.

The first theist widely known to have made such an argument is Frederick Robert Tennant. As he

puts the matter, in Volume 2 of Philosophical Theology, “the multitude of interwoven

adaptations by which the world is constituted a theatre of life, intelligence, and morality, cannot

reasonably be regarded as an outcome of mechanism, or of blind formative power, or aught but

purposive intelligence” (Tennant 1928-30, 121). In effect, this influential move infers design, not

from the existence of functionally complex organisms, but from the purposive quality of the

evolutionary process itself. Evolution is, on this line of response, guided by an intelligent Deity.

2. Contemporary Versions of the Design Argument

Contemporary versions of the design argument typically attempt to articulate a more

sophisticated strategy for detecting evidence of design in the world. These versions typically

contain three main elements—though they are not always explicitly articulated. First, they

identify some property P that is thought to be a probabilistically reliable index of design in the

following sense: a design explanation for P is significantly more probable than any explanation

that relies on chance or random processes. Second they argue that some feature or features of the

world exhibits P. Third, they conclude that the design explanation is significantly more likely to

be true.

As we will see, however, all of the contemporary versions of the design inference seem to be

vulnerable to roughly the same objection. While each of the design inferences in these arguments

has legitimate empirical uses, those uses occur only in contexts where we have strong antecedent

reason for believing there exist intelligent agents with the ability to bring about the relevant

event, entity, or property. But since it is the very existence of such a being that is at issue in the

debates about the existence of God, design arguments appear unable to stand by themselves as

arguments for God’s existence.

a. The Argument from Irreducible Biochemical Complexity

Design theorists distinguish two types of complexity that can be instantiated by any given

structure. As William Dembski describes the distinction: a system or structure is cumulatively

complex “if the components of the system can be arranged sequentially so that the successive

removal of components never leads to the complete loss of function”; a system or structure is

irreducibly complex “if it consists of several interrelated parts so that removing even one part

completely destroys the system’s function” (Dembski 1999, 147). A city is cumulatively

complex since one can successively remove people, services, and buildings without rendering it

unable to perform its function. A mousetrap, in contrast, is irreducibly complex because the

removal of even one part results in complete loss of function.

Design proponents, like Michael J. Behe, have identified a number of biochemical systems that

they take to be irreducibly complex. Like the functions of a watch or a mousetrap, a cilium

cannot perform its function unless its microtubules, nexin linkers, and motor proteins are all

arranged and structured in precisely the manner in which they are structured; remove any

component from the system and it cannot perform its function. Similarly, the blood-clotting

function cannot perform its function if either of its key ingredients, vitamin K and

antihemophilic factor, are missing. Both systems are, on this view, irreducibly complex—rather

than cumulatively complex.

Though Behe states his conclusion in categorical terms (that is, irreducibly complex systems

“cannot be produced gradually”), he is more charitably construed as claiming only that the

probability of gradually producing irreducibly complex systems is very small. The stronger

construction of the conclusion (and argument) incorrectly presupposes that Darwinian theory

implies that every precursor to a fully functional system must itself perform some function that

makes the organism more fit to survive. Organisms that have, say, a precursor to a fully

functional cilium are no fitter than they would have been without it, but there is nothing in

Darwinian theory that implies they are necessarily any less fit. Thus, there is no reason to think

that it is logically or nomologically impossible, according to Darwinian theory, for a set of

organisms with a precursor to a fully functional cilium to evolve into a set of organisms that has

fully functional cilia. Accordingly, the argument from irreducible biochemical complexity is

more plausibly construed as showing that the design explanation for such complexity is more

probable than the evolutionary explanation.

Nevertheless, this more modest interpretation is problematic. First, there is little reason to think

that the probability of evolving irreducibly complex systems is, as a general matter, small enough

to warrant assuming that the probability of the design explanation must be higher. If having a

precursor to an irreducibly complex system does not render the organism less fit for survival, the

probability a subspecies of organisms with the precursor survives and propagates is the same,

other things being equal, as the probability that a subspecies of organisms without the precursor

survives and propagates. In such cases, then, the prospect that the subspecies with the precursor

will continue to thrive, leave offspring, and evolve is not unusually small.

Accordingly, even if we knew that the prospect that the precursor-subspecies would survive was

“vanishingly small,” as Behe believes, we would not be justified in inferring a design

explanation on probabilistic grounds. To infer that the design explanation is more probable than

an explanation of vanishingly small probability, we need some reason to think that the

probability of the design explanation is not vanishingly small. The problem, however, is that the

claim that a complex system has some property that would be valued by an intelligent agent with

the right abilities, by itself, simply does not justify inferring that the probability that such an

agent exists and brought about the existence of that system is not vanishingly small. In the

absence of some further information about the probability that such an agent exists, we cannot

legitimately infer design as the explanation of irreducible biochemical complexity.

b. The Argument from Biological Information

While the argument from irreducible biochemical complexity focuses on the probability of

evolving irreducibly complex living systems or organisms from simpler living systems or

organisms, the argument from biological information focuses on the problem of generating living

organisms in the first place. Darwinian theories are intended only to explain how it is that more

complex living organisms developed from primordially simple living organisms, and hence do

not even purport to explain the origin of the latter. The argument from biological information is

concerned with an explanation of how it is that the world went from a state in which it contained

no living organisms to a state in which it contained living organisms; that is to say, it is

concerned with the explanation of the very first forms of life.

There are two distinct problems involved in explaining the origin of life from a naturalistic

standpoint. The first is to explain how it is that a set of non-organic substances could combine to

produce the amino acids that are the building blocks of every living substance. The second is to

explain the origin of the information expressed by the sequences of nucleotides that form DNA

molecules. The argument from biological information is concerned with only the second of these

problems. In particular, it attempts to evaluate four potential explanations for the origin of

biological information: (1) chance; (2) a pre-biotic form of natural selection; (3) chemical

necessity; and (4) intelligent design. The argument concludes that intelligent design is the most

probable explanation for the information present in large biomacromolecules like DNA, RNA,

and proteins.

The argument proceeds as follows. Pre-biotic natural selection and chemical necessity cannot, as

a logical matter, explain the origin of biological information. Theories of pre-biotic natural

selection are problematic because they illicitly assume the very feature they are trying to explain.

These explanations proceed by asserting that the most complex nonliving molecules will

reproduce more efficiently than less complex nonliving molecules. But, in doing so, they assume

that nonliving chemicals instantiate precisely the kind of replication mechanism that biological

information is needed to explain in the case of living organisms. In the absence of some sort of

explanation as to how non-organic reproduction could occur, theories of pre-biotic natural

selection fail.

Theories of chemical necessity are problematic because chemical necessity can explain, at most,

the development of highly repetitive ordered sequences incapable of representing information.

Because processes involving chemical necessity are highly regular and predictable in character,

they are capable of producing only highly repetitive sequences of “letters.” For example, while

chemical necessity could presumably explain a sequence like “ababababababab,” it cannot

explain specified but highly irregular sequences like “the house is on fire.” The problem is that

highly repetitive sequences like the former are not sufficiently complex and varied to express

information. Thus, while chemical necessity can explain periodic order among nucleotide letters,

it lacks the resources logically needed to explain the periodic, highly specified, complexity of a

sequence capable of expressing information.

Ultimately, this leaves only chance and design as logically viable explanations of biological

information. Although it is logically possible to obtain functioning sequences of amino acids

through purely random processes, some researchers have estimated the probability of doing so

under the most favorable of assumptions at approximately 1 in 1065. Factoring in more realistic

assumptions about pre-biotic conditions, Meyer argues the probability of generating short

functional protein is 1 in 10125—a number that is vanishingly small. Meyer concludes: “given the

complexity of proteins, it is extremely unlikely that a random search through all the possible

amino acid sequences could generate even a single relatively short functional protein in the time

available since the beginning of the universe (let alone the time available on the early earth)”

(Meyer 2002, 75).

The problem, however, is that it is the very existence of an intelligent Deity that is at issue. In the

absence of some antecedent reason for thinking there exists an intelligent Deity capable of

creating biological information, the occurrence of sequences of nucleotides that can be described

as “representing information” does not obviously warrant an inference of intelligent design—no

matter how improbable the chance explanation might be. To justify preferring one explanation as

more probable than another, we must have information about the probability of each explanation.

The mere fact that certain sequences take a certain shape that we can see meaning or value in, by

itself, tells us nothing obvious about the probability that it is the result of intelligent design.

It is true, of course, that “experience affirms that information content not only routinely arises

but always arises from the activity of intelligent minds” (Meyer 2002, 92), but our experience is

limited to the activity of human beings—beings that are frequently engaged in activities that are

intended to produce information content. While that experience will inductively justify inferring

that some human agency is the cause of any information that could be explained by human

beings, it will not inductively justify inferring the existence of an intelligent agency with causal

powers that depart as radically from our experience as the powers that are traditionally attributed

to God. The argument from biological information, like the argument from biochemical

complexity, seems incapable of standing alone as an argument for God’s existence.

c. The Fine-Tuning Arguments

Scientists have determined that life in the universe would not be possible if more than about two

dozen properties of the universe were even slightly different from what they are; as the matter is

commonly put, the universe appears “fine-tuned” for life. For example, life would not be

possible if the force of the big bang explosion had differed by one part in 1060; the universe

would have either collapsed on itself or expanded too rapidly for stars to form. Similarly, life

would not be possible if the force binding protons to neutrons differed by even five percent.

It is immediately tempting to think that the probability of a fine-tuned universe is so small that

intelligent design simply must be the more probable explanation. The supposition that it is a

matter of chance that so many things could be exactly what they need to be for life to exist in the

universe just seems implausibly improbable. Since, on this intuition, the only two explanations

for the highly improbable appearance of fine-tuning are chance and an intelligent agent who

deliberately designed the universe to be hospitable to life, the latter simply has to be the better

explanation.

This natural line of argument is vulnerable to a cogent objection. The mere fact that it is

enormously improbable that an event occurred by chance, by itself, gives us no reason to think

that it occurred by design. Suppose we flip a fair coin 1000 times and record the results in

succession. The probability of getting the particular outcome is vanishingly small: 1 in 21000 to be

precise. But it is clear that the mere fact that such a sequence is so improbable, by itself, does not

give us any reason to think that it was the result of intelligent design. As intuitively tempting as it

may be to conclude from just the apparent improbability of a fine-tuned universe that it is the

result of divine agency, the inference is unsound.

i. The Argument from Suspicious Improbability’s

George N. Schlesinger, however, attempts to formalize the fine-tuning intuition in a way that

avoids this objection. To understand Schlesinger’s argument, consider your reaction to two

different events. If John wins a 1-in-1,000,000,000 lottery game, you would not immediately be

tempted to think that John (or someone acting on his behalf) cheated. If, however, John won

three consecutive 1-in-1,000 lotteries, you would immediately be tempted to think that John (or

someone acting on his behalf) cheated. Schlesinger believes that the intuitive reaction to these

two scenarios is epistemically justified. The structure of the latter event is such that it is justifies

a belief that intelligent design is the cause: the fact that John got lucky in three consecutive

lotteries is a reliable indicator that his winning was the intended result of someone’s intelligent

agency. Despite the fact that the probability of winning three consecutive 1-in-1,000 games is

exactly the same as the probability of winning one 1-in-1,000,000,000 game, the former event is

of a kind that is surprising in a way that warrants an inference of intelligent design.

Schlesinger argues that the fact that the universe is fine-tuned for life is improbable in exactly the

same way that John’s winning three consecutive lotteries is improbable. After all, it is not just

that we got lucky with respect to one property-lottery game; we got lucky with respect to two

dozen property-lottery games—lotteries that we had to win in order for there to be life in the

universe. Given that we are justified in inferring intelligent design in the case of John’s winning

three consecutive lotteries, we are even more justified in inferring intelligent design in the case

of our winning two dozen much more improbable property lotteries. Thus, Schlesinger

concludes, the most probable explanation for the remarkable fact that the universe has exactly

the right properties to sustain life is that an intelligent Deity intentionally created the universe

such as to sustain life.

This argument is vulnerable to a number of criticisms. First, while it might be clear that carbon-

based life would not be possible if the universe were slightly different with respect to these two-

dozen fine-tuned properties, it is not clear that no form of life would be possible. Second, some

physicists speculate that this physical universe is but one material universe in a “multiverse” in

which all possible material universes are ultimately realized. If this highly speculative hypothesis

is correct, then there is nothing particularly suspicious about the fact that there is a fine-tuned

universe, since the existence of such a universe is inevitable (that is, has probability 1) if all

every material universe is eventually realized in the multiverse. Since some universe, so to

speak, had to win, the fact that ours won does not demand any special explanation.

As before, the problem for the fine-tuning argument is that we lack both of the pieces that are

needed to justify an inference of design. First, the very point of the argument is to establish the

fact that there exists an intelligent agency that has the right causal abilities and motivations to

bring the existence of a universe capable of sustaining life. Second, and more obviously, we do

not have any past experience with the genesis of worlds and are hence not in a position to know

whether the existence of fine-tuned universes are usually explained by the deliberate agency of

some intelligent agency. Because we lack this essential background information, we are not

justified in inferring that there exists an intelligent Deity who deliberately created a universe

capable of sustaining life.

ii. The Confirmatory Argument

Robin Collins defends a more modest version of the fine-tuning argument that relies on a general

principle of confirmation theory, rather than a principle that is contrived to distinguish events or

entities that are explained by intelligent design from events or entities explained by other factors.

Collins’s version of the argument relies on what he calls the Prime Principle of Confirmation: If

observation O is more probable under hypothesis H1 than under hypothesis H2, then O provides

a reason for preferring H1 over H2. The idea is that the fact that an observation is more likely

under the assumption that H1 is true than under the assumption H2 is true counts as evidence in

favor of H1.

This version of the fine-tuning argument proceeds by comparing the relative likelihood of a fine-

tuned universe under two hypotheses:

1. The Design Hypothesis: there exists a God who created the universe such as to sustain

life;

2. The Atheistic Single-Universe Hypothesis: there exists one material universe, and it is a

matter of chance that the universe has the fine-tuned properties needed to sustain life.

Assuming the Design Hypothesis is true, the probability that the universe has the fine-tuned

properties approaches (if it does not equal) 1. Assuming the Atheistic Single-Universe

Hypothesis is true, the probability that the universe has the fine-tuned properties is very small—

though it is not clear exactly how small. Applying the Prime Principle of Confirmation, Collins

concludes that the observation of fine-tuned properties provides reason for preferring the Design

Hypothesis over the Atheistic Single-Universe Hypothesis.

At the outset, it is crucial to note that Collins does not intend the fine-tuned argument as a proof

of God’s existence. As he explains, the Prime Principle of Confirmation “is a general principle of

reasoning which tells us when some observation counts as evidence in favor of one hypothesis

over another” (Collins 1999, 51). Indeed, he explicitly acknowledges that “the argument does not

say that the fine-tuning evidence proves that the universe was designed, or even that it is likely

that the universe was designed” (Collins 1999, 53). It tells us only that the observation of fine-

tuning provides one reason for accepting the Theistic Hypothesis over the Atheistic Single-

Universe Hypothesis—and one that can be rebutted by other evidence.

The confirmatory version of the fine-tuning argument is not vulnerable to the objection that it

relies on an inference strategy that presupposes that we have independent evidence for thinking

the right kind of intelligent agency exists. As a general scientific principle, the Prime Principle of

Confirmation can be applied in a wide variety of circumstances and is not limited to

circumstances in which we have other reasons to believe the relevant conclusion is true. If the

observation of a fine-tuned universe is more probable under the Theistic Hypothesis than under

the Atheistic Single-Universe Hypothesis, then this fact is a reason for preferring the Design

Hypothesis to Atheistic Single-Universe Hypothesis.

As is readily evident, the above reasoning, by itself, provides very weak support for the Theistic

Lottery Hypothesis. If all we know about the world is that John Doe won a lottery and the only

possible explanations for this observation are the Theistic Lottery Hypothesis and the Chance

Lottery Hypothesis, then this observation provides some reason to prefer the former. But it does

not take much counterevidence to rebut the Theistic Lottery Hypothesis: a single observation of a

lottery that relies on a random selection process will suffice. A single application of the Prime

Principle of Confirmation, by itself, is simply not designed to provide the sort of reason that

would warrant much confidence in preferring one hypothesis to another.

For this reason, the confirmatory version of the fine-tuning argument, by itself, provides a weak

reason for preferring the Design Hypothesis over the Atheistic Single Universe Hypothesis.

Although Collins is certainly correct in thinking the observation of fine-tuning provides a reason

for accepting the Design Hypothesis and hence rational ground for belief that God exists, that

reason is simply not strong enough to do much in the way of changing the minds of either

agnostics or atheists.

3. The Scientifically Legitimate Uses of Design Inferences

It is worth noting that proponents are correct in thinking that design inferences have a variety of

legitimate scientific uses. Such inferences are used to detect intelligent agency in a large variety

of contexts, including criminal and insurance investigations. Consider, for example, the

notorious case of Nicholas Caputo. Caputo, a member of the Democratic Party, was a public

official responsible for conducting drawings to determine the relative ballot positions of

Democrats and Republicans. During Caputo’s tenure, the Democrats drew the top ballot position

40 of 41 times, making it far more likely that an undecided voter would vote for the Democratic

candidate than for the Republican candidate. The Republican Party filed suit against Caputo,

arguing he deliberately rigged the ballot to favor his own party. After noting that the probability

of picking the Democrats 40 out of 41 times was less than 1 in 50 billion, the court legitimately

made a design inference, concluding that “few persons of reason will accept the explanation of

blind chance.”

What proponents of design arguments for God’s existence, however, have not noticed is that

each one of these indubitably legitimate uses occurs in a context in which we are already

justified in thinking that intelligent beings with the right motivations and abilities exist. In every

context in which design inferences are routinely made by scientists, they already have conclusive

independent reason for believing there exist intelligent agents with the right abilities and

motivations to bring about the apparent instance of design.

In response, one might be tempted to argue that there is one context in which scientists employ

the design inference without already having sufficient reason to think the right sort of intelligent

agency exists. As is well-known, researchers monitor radio transmissions for patterns that would

support a design inference that such transmissions are sent by intelligent beings. For example, it

would be reasonable to infer that some intelligent extraterrestrial beings were responsible for a

transmission of discrete signals and pauses that effectively enumerated the prime numbers from

2 to 101. In this case, the intelligibility of the pattern, together with the improbability of its

occurring randomly, seems to justify the inference that the transmission sequence is the result of

intelligent design.

As it turns out, we are already justified in thinking that the right sort of intelligent beings exist

even in this case. We already know, after all, that we exist and have the right sort of motivations

and abilities to bring about such transmissions because we send them into space hoping that

some other life form will detect our existence. While our existence in the universe—and this is

crucial—does not, by itself, justify thinking that there are other intelligent life forms in the

universe, it does justify thinking that the probability that there are such life forms is higher than

the astronomically small probability (1 in 21136 to be precise) that a sequence of discrete radio

signals and pauses that enumerates the prime numbers from 2 to 101 is the result of chance.

Thus, we would be justified in inferring design as the explanation of such a sequence on the

strength of three facts: (1) the probability of such a chance occurrence is 1 in 21136; (2) there exist

intelligent beings in the universe capable of bringing about such an occurrence; and (3) the

sequence of discrete signals and pauses has a special significance to intelligent beings. In

particular, (2) and (3) tell us that the probability that design explains such an occurrence is

significantly higher than 1 in 21136—though it is not clear exactly what the probability is.

In so far as the legitimate application of design inferences presupposes that we have antecedent

reason to believe the right kind of intelligent being exists, they can enable us to distinguish what

such beings do from what merely happens. If we already know, for example, that there exist

beings capable of rigging a lottery, then design inferences can enable us to distinguish lottery

results that merely happen from lottery results that are deliberately brought about by such agents.

Similarly, if we already have adequate reason to believe that God exists, then design inferences

can enable us to distinguish features of the world that merely happen from features of the world

that are deliberately brought about by the agency of God. Indeed, to the extent that we are

antecedently justified in believing that God exists, it is obviously more reasonable to believe that

God deliberately structured the universe to have the fine-tuned properties than it is to believe that

somehow this occurred by chance.

Conclusion

If this is correct, then design inferences simply cannot do the job they are asked to do in design

arguments for God’s existence. Insofar as they presuppose that we already know the right kind of

intelligent being exists, they cannot stand alone as a justification for believing that God exists. It

is the very existence of the right kind of intelligent being that is at issue in the dispute over

whether God exists. While design inferences have a variety of scientifically legitimate uses, they

cannot stand alone as arguments for God’s existence.

References

Michael J. Behe, Darwin’s Black Box: The Biochemical Challenge to Evolution (New

York: Touchstone Books, 1996)

Richard Bentley, A Confutation of Atheism from the Origin and Frame of the World

(London: H. Mortlock, 1692-1693)

Robin Collins, “A Scientific Argument for the Existence of God,” in Michael J. Murray

(ed.), Reason for the Hope Within (Grand Rapids, MI: William B. Eerdmans Publishing

Co., 1999)

Charles Darwin, The Origin of Species, Everyman’s Library (London: J.M. Dent, 1947)

Richard Dawkins, The Blind Watchmaker: Why the Evidence of Evolution Reveals a

Universe without Design (New York: Norton Publishing, 1996; originally published in

1986)

William Dembski, The Design Inference (Cambridge: Cambridge University Press, 1998)

William Dembski, No Free Lunch: Why Specified Complexity Cannot Be Purchased

without Intelligence (Rowman & Littlefield, 2002)