Book Review: Natural Theology by William Paley

Natural theology is the practice of inferring the existence of God from the design and beauty found in nature. Hence, the full title of William Paley’s 1802 Natural Theology is: Natural Theology, or, Evidence of the Existence and Attributes of the Deity, collected from the appearances of nature. As a literary work, Paley’s Natural Theology became a best seller and remains a classic.

Even those who have not read Paley may be familiar with his famous watch analogy. Paley tells of how if one were to find a watch in nature, one would infer a designer because of the structure, order, purpose, and design found in the watch. The features of the watch have all the hallmarks of design. Paley then shows how the manifold features of natural structures also have similar marks of design: complex organization, order, purpose, and apparent features of design. “There cannot be a design without a designer; contrivance without a contriver; order without choice; arrangement, without any thing capable of arranging…”1



Some reject the simple potency of Paley’s watch analogy, all the while ignoring the rest of his book. While he takes only a few pages on the initial watch analogy (including the wonder one might find if the watch happened to be equipped to replicate itself) the rest of his work builds cumulatively with example after example from human anatomy, animal bodies, plant life, and astronomy. The examples and detail Paley presents are amazing in both quantity and literary quality. Even with the age of his book, the extent to which Paley draws from the scientific information available to him is truly impressive, and, one could argue, is still persuasive in light of contemporary science. But this is a judgment the reader must make from his own evaluation of Paley’s book.

Paley seemed to have a legal mindset. His book is a cumulative case and relies heavily on probability. He describes his approach:

The proof is not a conclusion, which lies at the end of a chain of reasoning, of which chain each instance of contrivance is only a link, and of which, if one link fail, the whole falls; but it is an argument separately supplied by every separate example…The argument is cumulative in the fullest sense of the term.2

Paley uses a cumulative case to show a designer and each example is part of a web of examples which all tie together. So even if a number of his examples could be disproven as evidence for design, the argument is not defeated – only weakened to an extent.

The author relies on analogy both to show the similarity between two similar structures (e.g., the comparison of the eye and a telescope), and also for rhetorical purposes. For example, comparing muscle features to systems of pulleys not only illustrates the manner in which the physical anatomy functions just like mechanical devices, but also creates memorable mental pictures for the reader. However, he does not push his analogies further than is warranted (i.e., the eye really does function in a similar way that a telescope does, etc.).

Paley divides his work into various sections, each wonderfully described in great detail. In dealing with human anatomy, Paley explores various notable features that are artful in structure and function, often pointing to subtle arrangements and constructions that are far more teleological in appearance than random. He reflects on the interaction of the muscles:

Now when we reflect upon the number of muscles...how contiguous they lie to each other, in layers, as it were, over one another, crossing one another, sometimes embedded in one another, sometimes perforating one another, an arrangement, which leaves to each its liberty and its full play, must necessarily require meditation and counsel.3

He continues: “What contrivance can be more mechanical than the following, viz. a slit in one tendon to let another tendon pass through it?”4 Paley continually points to the peculiar, yet functional contrivances found throughout not only the human body, but in animal bodies and nature: air bladders within fish, the venomous fang of a viper, the tongue of a woodpecker.

Paley is also interested in the interaction of the systems of anatomy, such as the organs and the circulation of the blood. These seem to be systems within systems, interdependent structures each with a role and purpose. In a sense, Paley is pointing to various “irreducible complexities” found all around; but he calls it relation:

When several different parts contribute to one effect; or...when an effect is produced by the joint action of different instruments; the fitness of such parts or instruments to one another, for the purpose of producing, by their united action, the effect, is what I call relation: and wherever this is observed in the works of nature or of man, it appears to me to carry along with it decisive evidence of understanding, intention, art.5

In addition, he notes the various qualities found in living things that he calls “future considerations.” These are certain features that only come into use later in the organism’s development, whether eyes in one animal, lungs in another, or the various senses that may develop only later in life. He points to processes of metamorphosis in moths and flies, the electrical shocks of eels, and countless other unique features. He explores the built-in knowledge that living things have in their instincts: propensities that are independent of instruction. The examples are numerous and interesting.

After elaborating on the features of design in plant life, Paley moves to an exploration of the aspects of astronomy. Interestingly enough, here the reader will find arguments for the fine-tuning of certain features ranging from the amount of water on the earth to the narrow limits of the laws of attraction.

Finally, Paley finishes his examples from nature to design and moves on to his theological and philosophical conclusions. Here we find, even before Darwin, Paley interacting with (and challenging) the concept of complex living things developing from very simple living things. For instance, he finds no evidence of smaller “lumps” of cells eventually growing into larger functioning organisms with limbs, organs, eyes, etc. The remainder of Natural Theology explores the attributes of God that can be inferred from various aspects of nature. This last section, while somewhat speculative on Paley’s part, is still a fascinating read.

Paley’s book contains technical descriptions and uses older language, but it is still absorbing reading. Even after two centuries its themes are more alive than ever in biology, astronomy, and philosophy. As a whole, William Paley’s Natural Theology is a remarkable book, still relevant today, and highly recommended.

1 William Paley, Natural Theology (New York, NY: Oxford University Press, 2006), p. 12.
2 Ibid., p. 46.
3 Ibid., p. 71.
4 Ibid., p. 79.
5 Ibid., p. 140.