Paley’s argument from design: Did Hume refute it, and is it an argument from analogy?

There are many modern-day skeptics who apparently still subscribe to the myth that the Scottish empiricist philosopher David Hume soundly refuted Rev. William Paley’s argument from design on philosophical grounds, even before Darwin supposedly refuted it on scientific grounds (see here, here and here for examples). The supposition is absurdly anachronistic: Hume died in 1776, and his posthumous Dialogues Concerning Natural Religion were published in 1779, but Paley’s Natural Theology was not published until 1802, three years before Paley’s death in 1805. Some of the more intelligent skeptics, such as Julian Baggini, are aware of this fact, but still make the risibly absurd claim (see here) that Hume anticipated and refuted Paley’s argument from design. The truth, however, is the complete reverse.

It turns out that Rev. Paley had already read Hume’s Dialogues Concerning Natural Religion; indeed, he even refers in passing to “Mr. Hume, in his posthumous dialogues” on page 512 of Chapter XXVI of his Natural Theology! Moreover, a careful examination of Paley’s design argument shows that he had anticipated and responded to all of Hume’s criticisms.

I’d like to begin by drawing attention to one major difference between the design argument put forward by the character Cleanthes (and subsequently refuted by Philo) in David Hume’s Dialogues Concerning Natural Religion, and the design argument formulated by William Paley. As Professor John Wright has pointed out in some online remarks on Hume’s Dialogues, Cleanthes’ design argument was an inductive argument based on an analogy between human artifacts (which we observe being produced by intelligent agents) and the machines we find in Nature, whereas Paley argued that we could immediately infer Intelligent Design from any machine we happen to find:

Paley thinks we infer the existence of an intelligent cause immediately from the observation of the machine itself. According to the argument which Cleanthes puts forward, the only reason we ascribe an intelligent cause to machines like watches, is because we discover from observation that they are created by beings with thought, wisdom and intelligence. (Paley had read Hume and was obviously aware of this difference in their arguments: see his answer to his first Objection.)

For Paley the inference from watch to intelligent watchmaker is no different from the inference from complex natural organisms to an intelligent designer. He is just trying to show you can make the same inference in both cases. For Cleanthes, on the other hand, it is important that we observe the maker in the case of the human productions and we do not in the case of the productions of nature. We observe the effects in both cases and that they are somewhat similar to each other. But we never observe the cause in the case of natural machines: it is only inferred through the scientific principle “like effects, like causes.” Cleanthes draws the conclusion that the cause of natural machines something like a human mind, but very much greater.

Cleanthes’ argument is a genuine inductive argument, based on observation of the relation of cause and effect in the case of human production; Paley’s is not.
I should add that Dr. Stephen Meyer, author of Signature in the Cell, made the same point in an online lecture he gave at Cambridge University in July 2012, entitled, Intelligent Design: The Most Credible Idea?. At about (52:30), Meyer addresses Hume’s objections to the design argument, as follows:

The other case against the design argument came from Hume, which was the claim that the design argument was a failed analogy. And what he did was, he said, “Look. You’ve got the structure of the analogical argument is that you’ve got two similar effects with a known cause, allowing us to infer a similar cause for the other effect.” That’s the logical structure of the analogical argument. Hume attempted to defeat that by showing that the similarity between effect E1 – human artifacts – and effect E2 – living systems – was much less than had been previously indicated. The structure of the argument that I’ve developed – and that other people in the ID research community are developing – is not an analogical argument, properly speaking. We’re not arguing from similarities of effects; rather, what we’re doing is picking out identical effects in both living systems and artifactual systems – in particular, specified complexity, which can be very rigorously defined – and saying, “OK, we’re looking at identical effects. Now what is the best causal explanation of that effect given our knowledge of cause and effect? So the argument does not have the logical structure of an analogical argument of the kind that Hume critiqued, but rather, of an inference to the best explanation – a standard scientific form of argumentation – and so the case I made is that Cause 4 – Intelligence – provides a better explanation, because it’s the only cause which is consistent with our knowledge of cause and effect as we observe it in the world around us, as we observe the causes now in operation.
Dr. Meyer is of course perfectly correct. In this post, what I propose to do is examine Hume’s criticisms of the design argument in detail, and show how Paley’s version of the design argument was specifically tailored to address those criticisms head-on.


Twelve myths about Paley’s design argument, or: Why everything you thought you knew about Paley’s Natural Theology is wrong
If you’ve read anything about Paley’s “design argument” for the existence of God, then you’ve probably heard it expressed in the following garbled form:

Rev. William Paley argued that there were strong similarities between complex structures that we find in Nature (such as the eye) and human artifacts, such as a watch. The human eye is like a machine, he claimed. So are the other organs of the body. But we already know from observation that mechanical artifacts, such as watches, are invariably designed by intelligent beings – namely, human beings. Operating on the principle, “like effects, like causes,” we can infer by analogy that complex organs, such as the eye, were probably made by an Intelligent Designer, Who is like a human being, but much, much smarter. Since this inference is based on an inductive argument (rather than a deductive one) which makes use of an analogy, its conclusion is not absolutely certain. Nevertheless, maintained Paley, it is extremely probable that an Intelligent Designer exists. Paley then went on to argue that since the whole world is rather like a giant watch, we may legitimately conclude that the universe was made by a Designer – a Cosmic Watchmaker, if you like.
You’ve probably also read about Hume’s allegedly devastating rebuttal of the Design argument, which basically goes like this:

First, Paley’s “watch analogy” for complex natural systems was never a very good one in the first place. The eye isn’t a watch, and neither is the universe. The numerous disanalogies between complex natural structures (such as the eye) and a human artifact, undermine the inference that these natural structures were designed. The design inference is even weaker when we examine the universe as a whole: in reality, it is nothing like a watch.

Second, the numerous defects that we find in the organs of living things constitute powerful evidence against the hypothesis that they were designed by an Intelligent Creator.

Third, even if we had good evidence for an Intelligent Designer of Nature, our experience tells us that intelligent designers are invariably complex entities, so we would then have to ask: who designed the Designer? And who designed the Designer’s Designer? And so on, ad infinitum. Wouldn’t it be more rational, then, to simply say that Nature is self-ordering, instead of opening the door to an infinite regress of designers, which in the end, explains nothing?

Fourth, even if we could establish the existence of a Designer of Nature who can somehow avoid this infinite regress, we would still faced with another question: how can the Designer of Nature be a bodiless agent, as theists maintain? Our experience tells us that intelligent agents are always embodied beings, and nobody has ever seen a disembodied agent making anything. There is no good evidence for spooks. The notion of a spiritual Designer is therefore both absurd and unsupported by any credible evidence.

Fifth, even if could make sense of the notion of a spiritual Designer, how can we be sure that there’s only one Designer of Nature? Might there not be many designers, as polytheism supposes?

Sixth, even if we could establish the unity of the Cosmic Watchmaker, such a Being would not need to be continually involved with the cosmos; maybe He created its complex systems at some point in the past, but He no longer interacts with the cosmos. So how do we know that the Designer of the cosmos is still alive?

Seventh, even if He still exists, we have no way of knowing whether the Cosmic Designer is a personal Being; for all we know, the Designer might be an impersonal force, like Spinoza’s Deity.

Finally, even if we could establish that the Designer is a personal Being, there is no way of demonstrating that He is infinitely powerful, wise or good. The effects we see in Nature are finite, and from a finite effect, it is illicit to infer the existence of an Infinite Cause.

We can only conclude, then, that Rev. William Paley’s identification of the Designer of Nature with the God of Judaism and Christianity in his Natural Theology is utterly unwarranted: it is a gigantic leap of faith which defies the laws of logic.
The above exposition of Paley’s design argument contains several errors, which I’ve collected together under the heading of twelve myths, which are commonly found in discussions of Paley’s argument for God’s existence. My refutation of these myths will enable readers to see clearly how Paley met and rebutted every one of the eight Humean criticisms listed above.

The biggest myth of them all: Paley failed to take biological reproduction into account, in his argument

Perhaps the biggest myth – especially among younger skeptics – is that Rev. Paley failed to take into account the rather obvious fact that organisms reproduce (and are therefore capable of refining and improving upon their internal bodily design with each generation), whereas artifacts typically don’t reproduce – which is why design inferences that work for watches don’t work for living things. At the end of my post, I’ll prove that Paley anticipated this very objection and rebutted it decisively, before going on to discuss briefly whether Darwin’s Origin of Species successfully refutes the logic of Paley’s argument.

Without further ado, allow me to present “Twelve myths about Paley’s design argument.”


Myth One: Paley likens the world to a giant watch in his Natural Theology.

Fact: Paley explicitly rejected the analogy between the world and a watch, in his Natural Theology. He points out that when making design inferences, “we deduce design from relation, aptitude, and correspondence of parts.” However, “the heavenly bodies do not, except perhaps in the instance of Saturn’s ring, present themselves to our observation as compounded of parts at all,” since they appear to be quite simple and undifferentiated in their internal structure (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXII, p. 379). When discussing the movements of the heavenly bodies, he writes: “Even those things which are made to imitate and represent them, such as orreries, planetaria, celestial globes, &c. bear no affinity to them, in the cause and principle by which their motions are actuated” (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXII, p. 379) – the reason being that the mechanism of a watch requires that its parts be in physical contact with one another, whereas the gravitational influence exerted by one heavenly body on another is action at a distance.

Indeed, nowhere in his Natural Theology does Paley declare that the world is like a watch. The closest statement I can find is his declaration, “The universe itself is a system; each part either depending upon other parts, or being connected with other parts by some common law of motion, or by the presence of some common substance” (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXV, pp. 449-450). To be sure, Paley does argue that “In the works of nature we trace mechanism” (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXIII, pp. 416-418), but he never declares that Nature itself is one giant mechanism. Rather, Paley’s proof of God was based on the existence of mechanisms (plural) occurring in the natural world.

What Paley does liken to watches are the biological structures (such as the eye) that we find in the natural world. For example, he writes that “very indication 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,” and in the same passage he adds that “here is precisely the same proof that the eye was made for vision, as there is that the telescope was made for assisting it” (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter III, pp. 17-18).

NOTE: I should like to point out here that when Paley speaks of contrivances, he simply means: systems whose parts are intricately arranged and co-ordinated to serve some common end, or as he puts it, a system possessing the following three features: “relation to an end, relation of parts to one another, and to a common purpose.” (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXIII, p. 413.) For the purposes of Paley’s argument, it is utterly irrelevant whether this end is intrinsic to the parts in question, as in a living organism, or extrinsic, as in an artifact.

Elsewhere, when discussing the example of the eye and other organs, he writes: “If there were but one watch in the world, it would not be less certain that it had a maker… Of this point, each machine is a proof, independently of all the rest. So it is with the evidences of a Divine agency… The eye proves it without the ear; the ear without the eye.” (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter VI, pages 76-77).


Myth Two: Paley’s argument for a Designer in his Natural Theology is an argument from analogy.

Fact: Paley’s argument is not based on any analogy. He doesn’t say that the complex organs found in living things are like artifacts; he says that they are the same as artifacts in certain vital respects. In particular, these complex organs share several common properties with artifacts: “properties, such as relation to an end, relation of parts to one another, and to a common purpose” (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXIII, p. 413), or as he puts it elsewhere, “[a]rrangement, disposition of parts, subserviency of means to an end, [and] relation of instruments to a use” (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter II, p. 11). Paley refers to the organs of the body as “contrivances,” precisely because they share these vital properties with man-made artifacts. (For the benefit of Thomist readers who may be wondering, I should point out that Paley is fully aware of the intrinsic teleology of living things, and that he repeatedly refers to “final causes” in his Natural Theology.)

Next, Paley argues that intelligence is the only known adequate cause of objects possessing the combination of properties found in artifacts and complex organs. Our experience tells us that that no other cause, apart from intelligence, is capable of producing effects possessing these properties. Paley concludes that the complex organs of living creatures (such as the eye) must therefore have had an Intelligent Designer. In his own words:

Wherever we see marks of contrivance, we are led for its cause to an intelligent author. And this transition of the understanding is founded upon uniform experience. We see intelligence constantly contriving, that is, we see intelligence constantly producing effects, marked and distinguished by certain properties; not certain particular properties, but by a kind and class of properties, such as relation to an end, relation of parts to one another, and to a common purpose. We see, wherever we are witnesses to the actual formation of things, nothing except intelligence producing effects so marked and distinguished. Furnished with this experience, we view the productions of nature. We observe them also marked and distinguished in the same manner. We wish to account for their origin. Our experience suggests a cause perfectly adequate to this account. No experience, no single instance or example, can be offered in favour of any other. In this cause therefore we ought to rest… Men are not deceived by this reasoning: for whenever it happens, as it sometimes does happen, that the truth comes to be known by direct information, it turns out to be what was expected. In like manner, and upon the same foundation (which in truth is that of experience), we conclude that the works of nature proceed from intelligence and design, because, in the properties of relation to a purpose, subserviency to a use, they resemble what intelligence and design are constantly producing, and what nothing except intelligence and design ever produce at all. (Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXIII, p. 413-414).
For Paley, the inference to design, upon seeing a contrivance, is immediate:

This mechanism being observed (it requires indeed an examination of the instrument, and perhaps some previous knowledge of the subject, to perceive and understand it; but being once, as we have said, observed and understood), the inference, we think, is inevitable, that the watch must have had a maker…

Nor would it, I apprehend, weaken the conclusion, that we had never seen a watch made; that we had never known an artist capable of making one; that we were altogether incapable of executing such a piece of workmanship ourselves, or of understanding in what manner it was performed…

Ignorance of this kind exalts our opinion of the unseen and unknown artist’s skill, if he be unseen and unknown, but raises no doubt in our minds of the existence and agency of such an artist, at some former time, and in some place or other. (Chapter I, pp. 3-4)

Myth Three: Paley put forward an inductive argument for a Designer: because there are complex systems in Nature which resemble human artifacts, which are made by intelligent agents, we can infer that an Intelligent Designer made Nature’s complex systems.

Fact: Paley himself declares on several occasions that his argument for a Designer of Nature is a deductive argument. Paley refers to his argument as a deductive argument in the following passages in his Natural Theology:

…the marks of contrivance discoverable in animal bodies, and to the argument deduced from them, in proof of design, and of a designing Creator…
(Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter IV, p. 67)
Now we deduce design from relation, aptitude, and correspondence of parts.

(Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXII, p. 379)
… the universality which enters into the idea of God, as deduced from the views of nature.
(Natural Theology. 12th edition. J. Faulder: London, 1809, Chapter XXIV, p. 443)
Nowhere in his Natural Theology does Paley ever describe his argument as an inductive one.

The premises and conclusion of Paley’s deductive design argument

The premises of Paley’s deductive argument are as follows. First, we know that intelligent agents are capable of producing effects marked by the three properties of (i) relation to an end, (ii) relation of the parts to one another, and (iii) possession of a common purpose.

Second, no other cause has ever been observed to produce effects possessing these three properties.

We are therefore entitled to conclude that if there are systems in Nature possessing these same three properties, then the only cause that is adequate to account for these natural effects is an Intelligent Agent.

The view that Paley’s argument is deductive has scholarly support

I would like to add that Thomist scholar Del Ratzsch, in his article on Teleological Arguments for God’s Existence in The Stanford Encyclopedia of Philosophy, also acknowledges that Paley’s argument is a deductive one. In his article, he writes:

Although Paley’s argument is routinely construed as analogical, it in fact contains an informal statement of the above variant argument type. Paley goes on for two chapters discussing the watch, discussing the properties in it which evince design, destroying potential objections to concluding design in the watch, and discussing what can and cannot be concluded about the watch’s designer. It is only then that entities in nature – e.g., the eye – come onto the horizon at all. Obviously, Paley isn’t making such heavy weather to persuade his readers to concede that the watch really is designed and has a designer. He is, in fact, teasing out the bases and procedures from and by which we should and should not reason about design and designers. Thus Paley’s use of the term “inference” in connection with the watch’s designer.

Once having acquired the relevant principles, then in Chapter 3 of Natural Theology – “Application of the Argument” – Paley applies the same argument (vs. presenting us with the other half of the analogical argument) to things in nature. The cases of human artifacts and nature represent two separate inference instances:

up to the limit, the reasoning is as clear and certain in the one case as in the other. (Paley 1802 [1963], 14)
But the instances are instances of the same inferential move:

there is precisely the same proof that the eye was made for vision as there is that the telescope was made for assisting it. (Paley 1802 [1963], 13)
The watch does play an obvious and crucial role – but as a paradigmatic instance of design inferences rather than as the analogical foundation for an inferential comparison.

… Indeed, it has been argued that Paley was aware of Hume’s earlier attacks on analogical design arguments, and deliberately structured his argument to avoid the relevant pitfalls. Paley’s own characterization of his argument would support this deductive classification…