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 incorporates "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 handywork." 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
are 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, 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:
If we see a house,… we conclude, with the greatest certainty, that
it had an architect or builder because this is precisely that species
of effect which we have experienced to proceed from that species of
cause. But surely you will not affirm that the universe bears such a
resemblance to a house that we can with the same certainty infer a
similar cause, or that the analogy is here entire and perfect (Hume,
Dialogues, Part II).
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:
[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 (Paley 1867, 1).
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, subtilty, 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).
Since the works of nature possess functional complexity, a reliable
indicator of intelligent design, we can justifiably conclude that
these works were created by an intelligent agent who designed them to
instantiate this property.
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.
Contemporary biologist, Richard Dawkins (1986), uses a programming
problem to show that the logic of the process renders the Darwinian
explanation significantly more probable than the design explanation.
Dawkins considers two ways in which one might program a computer to
generate the following sequence of characters: METHINKS IT IS LIKE A
WEASEL. The first program randomly producing a new 28-character
sequence each time it is run; since the program starts over each time,
it incorporates a "single-step selection process." The probability of
randomly generating the target sequence on any given try is 2728 (that
is, 27 characters selected for each of the 28 positions in the
sequence), which amounts to about 1 in (10,000 x 1,000,0006). While a
computer running eternally would eventually produce the sequence,
Dawkins estimates that it would take 1,000,0005 years—which is
1,000,0003 years longer than the universe has existed. As is readily
evident, a program that selects numbers by means of such a
"single-step selection mechanism" has a very low probability of
reaching the target.
The second program incorporates a "cumulative-step selection
mechanism." It begins by randomly generating a 28-character sequence
of letters and spaces and then "breeds" from this sequence in the
following way. For a specified period of time, it generates copies of
itself; most of the copies perfectly replicate the sequence, but some
copies have errors (or mutations). At the end of this period, it
compares all of the sequences with the target sequence METHINKS IT IS
LIKE A WEASEL and keeps the sequence that most closely resembles it.
For example, a sequence that has an E in the second place more closely
resembles a sequence that is exactly like the first except that it has
a Q in the second place. It then begins breeding from this new
sequence in exactly the same way. Unlike the first program which
starts afresh with each try, the second program builds on previous
steps, getting successively closer to the program as it breeds from
the sequence closest to the target. This feature of the program
increases the probability of reaching the sequence to such an extent
that a computer running this program hit the target sequence after 43
generations, which took about half-an-hour.
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. While this might be true of explanations that rely entirely on
random single-step selection mechanisms, this is not true of Darwinian
explanations. 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.
According to Behe, the probability of evolving irreducibly complex
systems along Darwinian lines is sufficiently small that it can be
ruled out as an explanation of irreducible biochemical complexity:
An irreducibly complex system cannot be produced … by slight,
successive modifications of a precursor system, because any precursor
to an irreducibly complex system that is missing a part is by
definition nonfunctional…. Since natural selection can only choose
systems that are already working, if a biological system cannot be
produced gradually it would have to arise as an integrated unit, in
one fell swoop, for natural selection to have anything to act on (Behe
1996, 39; emphasis added).
Since, for example, a cilium-precursor (that is, one that lacks at
least one of a cilium's parts) cannot perform the function that endows
a cilium with adaptive value, organisms that have the cilium-precursor
are no "fitter for survival" than they would have been without it.
Since chance-driven evolutionary processes would not select organisms
with the precursor, intelligent design is a better explanation for the
existence of organisms with fully functional cilia.
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.
Second, the claim that intelligent agents of a certain kind would (or
should) see functional value in a complex system, by itself, says very
little about the probability of any particular causal explanation.
While this claim surely implies that intelligent agents with the right
causal abilities have a reason for bringing about such systems, it
does not tell us anything determinate about whether it is likely that
intelligent agents with the right causal powers did bring such systems
about—because it does not tell us anything determinate about whether
it is probable that such agents exist. As a logical matter, the mere
fact that some existing thing has a feature, irreducibly complex or
otherwise, that would be valuable to an intelligent being with certain
properties, by itself, does not say anything about the probability
that such a being exists.
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 precise
ordering of the four nucleotides, adenine, thymine, guanine, and
cytosine (A, T, G, and C, for short), determine the specific
operations that occur within a living cell and is hence fairly
characterized as representing (or embodying) information. As Stephen
C. Meyer puts the point: "just as the letters in the alphabet of a
written language may convey a particular message depending on their
sequence, so too do the sequences of nucleotides or bases in the DNA
molecule convey precise biochemical instructions that direct protein
synthesis within the cell" (Meyer 1998, 526).
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 aperiodic, 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).
Next, Meyer argues that the probability of the design explanation for
the origin of biological information is considerably higher:
[O]ne can detect the past action of an intelligent cause from the
presence of an information-rich effect, even if the cause itself
cannot be directly observed. For instances, visitors to the gardens of
Victoria harbor in Canada correctly infer the activity of intelligent
agents when they see a pattern of red and yellow flowers spelling
"Welcome to Victoria", even if they did not see the flowers planted
and arranged. Similarly, the specifically arranged nucleotide
sequences—the complex but functionally specified sequences—in DNA
imply the past action of an intelligent mind, even if such mental
agency cannot be directly observed (Meyer 2002, 93).
Further, scientists in many fields typically infer the causal activity
of intelligent agents from the occurrence of information content. As
Meyer rightly observes by way of example, "[a]rcheologists assume a
mind produced the inscriptions on the Rosetta Stone" (Meyer 2002, 94).
Meyer's reasoning appears vulnerable to the same objection to which
the argument from biochemical complexity is vulnerable. In all of the
contexts in which we legitimately make the design inference in
response to an observation of information, we already know that there
exist intelligent agents with the right sorts of motivations and
abilities to produce information content; after all, we know that
human beings exist and are frequently engaged in the production and
transmission of information. It is precisely because we have this
background knowledge that we can justifiably be confident that
intelligent design is a far more probable explanation than chance for
any occurrence of information that a human being is capable of
producing. In the absence of antecedent reason for thinking there
exist intelligent agents capable of creating information content, the
occurrence of a pattern of flowers in the shape of "Welcome to
Victoria" would not obviously warrant an inference of intelligent
design.
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 Improbabilitys
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.
Schlesinger's fine-tuning argument also appears vulnerable to the same
criticism as the other versions of the design argument (see Himma
2002). While Schlesinger is undoubtedly correct in thinking that we
are justified in suspecting design in the case where John wins three
consecutive lotteries, it is because—and only because—we know two
related empirical facts about such events. First, we already know that
there exist intelligent agents who have the right motivations and
causal abilities to deliberately bring about such events. Second, we
know from past experience with such events that they are usually
explained by the deliberate agency of one or more of these agents.
Without at least one of these two pieces of information, we are not
obviously justified in seeing design in such cases.
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.
Nevertheless, the confirmatory version of the argument is vulnerable
on other fronts. As a first step towards seeing one worry, consider
two possible explanations for the observation that John Doe wins a
1-in-7,000,000 lottery (see Himma 2002). According to the Theistic
Lottery Hypothesis, God wanted John Doe to win and deliberately
brought it about that his numbers were drawn. According to the Chance
Lottery Hypothesis, John Doe's numbers were drawn by chance. It is
clear that John's winning the lottery is vastly more probable under
the Theistic Lottery Hypothesis than under the Chance Lottery
Hypothesis. By the Prime Principle of Confirmation, then, John's
winning the lottery provides a reason to prefer the Theistic Lottery
Hypothesis over the Chance Lottery 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.
Consider, for example, how much more information was available to the
court in the Caputo case than is available to the proponent of the
design argument for God's existence. Like the proponent of the design
argument, the court knew that (1) the relevant event or feature is
something that might be valued by an intelligent agent; and (2) the
odds of it coming about by chance are astronomically small. Unlike the
proponent of the design argument, however, the court had an additional
piece of information available to it: the court already knew that
there existed an intelligent agent with the right causal abilities and
motives to bring about the event; after all, there was no dispute
whatsoever about the existence of Caputo. It was that piece of
information, together with (1), that enabled the court to justifiably
conclude that the probability that an intelligent agent deliberately
brought it about that the Democrats received the top ballot position
40 of 41 times was significantly higher than the probability that this
happened by chance. Without this crucial piece of information,
however, the court would not have been so obviously justified in
making the design inference. Accordingly, while the court was right to
infer a design explanation in the Caputo case, this is, in part,
because the judges already knew that the right kind of intelligent
beings exist—and one of them happened to have occupied a position that
afforded him with the opportunity to rig the drawings in favor of the
Democrats.
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.
Insofar 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.
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.
4. References and Further Reading
* 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)
* William Derham, Physico-theology, or, A Demonstration of the
Being and Attributes of God from his Works of Creation Being the
Substance of XVI Sermons Preached in St. Mary le Bow-Church, London,
at the Hon'ble Mr. Boyle's Lectures in the Years 1711 and 1712
(London: W. Innys, 1713)
* William Derham, Astro-theology, or, A Demonstration of the Being
and Attributes of God: From a Survey of the Heavens (London: W. Innys,
1715)
* Kenneth Einar Himma, "Prior Probabilities and Confirmation
Theory: A Problem with the Fine-Tuning Argument," International
Journal for Philosophy of Religion, vol. 51, no. 4 (June 2002)
* Kenneth Einar Himma, "The Application-Conditions for Design
Inferences: Why the Design Arguments Need the Help of Other Arguments
for God's Existence,"International Journal for Philosophy of
Religion., vol. 57, no. 1 (February 2005).
* David Hume, Dialogues Concerning Natural Religion, edited with
an introduction by Norman Kemp Smith, (New York: Social Sciences
Publishers, 1948)
* Julian Huxley, Evolution as Process (New York: Harper and Row, 1953).
* Stephen C. Meyer, "DNA by Design: An Inference to the Best
Explanation," Rhetoric and Public Affairs, vol. 1, no. 4 (Winter 1998)
* Stephen C. Meyer, "Evidence for Design in Physics and Biology:
From the Origin of the Universe to the Origin of Life," in Behe,
Dembski, and Meyer (eds.), Science and Evidence for Design in the
Universe (San Francisco: Ignatius Press, 2002)
* William Paley, Natural Theology: Or Evidences of the Existence
and Attributes of the Deity Collected from the Appearances of Nature
(Boston: Gould and Lincoln, 1867)
* Del Ratzsch, Nature, Design, and Science: The Status of Design
in Natural Science (Albany, NY: SUNY Press, 2001)
* John Ray, The Wisdom of God Manifested in the Works of the
Creation Being the Substance of Some Common Places Delivered in the
Chappel of Trinity-College, in Cambridge (London: Printed for Samuel
Smith, 1691)
* Hugh Ross, Beyond the Cosmos: What Recent Discoveries in
Astronomy and Physics Reveal about the Nature of God (Colorado
Springs: Nav Press, 1996)
* George N. Schlesinger, New Perspectives on Old-time Religion
(Oxford: Clarendon Press, 1988)
* Frederick Robert Tennant, Philosophical Theology, Volume 2 (1928-30)
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