William Paley's Natural Theology; or Evidences of the Existence and Attributes of the Deity, published in 1802, was the most widely read philosophical-theological book in early nineteenth-century Britain. For the first half of the century it was required reading at Cambridge, where Charles Darwin encountered it as an undergraduate and found it the most convincing of his required texts. Paley's watchmaker analogy - the argument that just as the complexity and purposiveness of a watch implies a watchmaker, so the complexity and purposiveness of natural organisms implies a divine designer - became the canonical statement of the teleological argument for God's existence. When Darwin published On the Origin of Species in 1859, proposing natural selection as a mechanism for apparent design without intentional agency, Paley's Natural Theology was the primary philosophical target - though Darwin claimed to have admired Paley's argumentation even as he destroyed its biological foundations.
The Thinker and His Work
William Paley (1743-1805) was an Anglican clergyman, the Archdeacon of Carlisle, and one of the most practically minded moral philosophers of the eighteenth century. His earlier Principles of Moral and Political Philosophy (1785) was a standard ethics textbook at Cambridge for decades, and his Horae Paulinae (1790) and A View of the Evidences of Christianity (1794) were exercises in historical and evidential apologetics. Natural Theology was his final work, written when he was suffering severely from ill health that made any sustained intellectual effort painful, and the evident passion with which he describes the wonders of animal anatomy - the eye, the ear, the wing, the joints of insects - gives it an unusual vitality for a work of philosophical argument.
Paley drew extensively on the natural history of his day, particularly on the anatomical work of John Hunter and the natural history of Gilbert White (The Natural History of Selborne), whose close observation of organisms Paley shared. His achievement was to synthesize the detailed empirical knowledge of natural history into a philosophical argument of unusual vividness and concreteness.
Biblical Texts Engaged
Psalm 19:1 - 'The heavens declare the glory of God, and the sky above proclaims his handiwork' - provides the biblical mandate for natural theology: the created world is a testimony to its Creator, and careful observation of that world is a form of worship. Paley's Natural Theology can be read as an extended commentary on this verse - a detailed account of precisely how and where God's handiwork is manifest in the anatomy and physiology of living creatures.
Romans 1:20 - 'For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made' - is Paul's warrant for natural theology. The apostle's claim that God's existence and nature can be known from creation grounds the entire enterprise of natural theology as a legitimate, indeed obligatory, mode of philosophical reflection.
Proverbs 3:19 - 'The Lord by wisdom founded the earth; by understanding he established the heavens' - expresses the biblical wisdom tradition's account of creation as the work of divine intelligence, which Paley's analogical argument seeks to make philosophically precise.
Core Argument
Paley's argument opens with his famous comparison: 'In crossing a heath, suppose I pitched my foot against a stone, and were asked how the stone came to be there, I might possibly answer, that for anything I knew to the contrary, it had lain there for ever... But suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place, I should hardly think of the answer I had before given.'
The difference between the stone and the watch is that the watch shows design: its parts are arranged precisely to produce a particular effect (telling the time), and this arrangement could not have come about by chance. The inference to a designer is therefore compelling. Natural organisms - above all, the human eye - show precisely this character: complex parts arranged with exquisite precision to produce particular effects. The inference to a designer is therefore at least as compelling for organisms as for watches, and the scale of the design (the multiplied millions of organisms on earth, each intricately organized) overwhelmingly confirms it.
Intellectual Context
Paley was working within the tradition of physico-theology that had flourished in seventeenth and eighteenth-century England, initiated by John Ray's The Wisdom of God Manifested in the Works of Creation (1691) and developed through the Boyle Lectures (established by Robert Boyle's will to defend Christianity against atheism). This tradition took seriously Newton's physics as testimony to divine intelligence: if the mathematical order of the cosmos implied a divine mathematician, the biological order of organisms implied a divine engineer. Paley's innovation was to focus on biological rather than astronomical evidence, making his argument more concrete and emotionally compelling than his predecessors.
Reception and Critique
Hume had anticipated the key objection in his Dialogues Concerning Natural Religion (1779, published posthumously): the analogy between artifacts and organisms is weak (organisms reproduce biologically, not mechanically; natural selection can produce apparent design without intentional agency), and even if it proved a designer, it would prove only a designer proportionate to the effect - not necessarily an infinitely good and powerful God. Paley did not engage Hume's Dialogues directly (scholars debate whether he had read them), but his Natural Theology is partly readable as a response to the Humean critique.
Darwin's natural selection provided the mechanism that Hume had lacked: a purely natural process that could generate the appearance of design without intentional agency. Darwin wrote in his Autobiography: 'I do not think I hardly ever admired a book more than Paley's Natural Theology... I could almost formerly have said it by heart.' And yet: 'The old argument of design in nature, as given by Paley, which formerly seemed to me so conclusive, fails, now that the law of natural selection has been discovered.'
Richard Dawkins's The Blind Watchmaker (1986) is titled as a direct response to Paley, arguing that natural selection is the 'blind watchmaker' - a cumulative process that produces apparent design without an watching intelligence.
Contemporary proponents of Intelligent Design (William Dembski, Michael Behe) argue that Paley's core intuition was correct but applied to the wrong level: it is not anatomical structures in general but irreducibly complex biochemical systems (the bacterial flagellum, the blood-clotting cascade) that resist explanation by natural selection and require design inference.
Legacy
Paley's Natural Theology established the terms within which the relationship between evolutionary biology and theism has been debated for two centuries. The contemporary 'fine-tuning' argument (that the cosmological constants are precisely calibrated to permit life, in a way that implies a cosmic designer) is a successor to Paley's design argument, now applied to physics rather than biology. Philosophers Richard Swinburne and Robin Collins have developed the most sophisticated recent versions of the fine-tuning design argument.
Key Passages
'Were there no example in the world of contrivance except that of the eye, it would be alone sufficient to support the conclusion which we draw from it, as to the necessity of an intelligent Creator. It could never be got rid of, because it could not be accounted for by any other supposition which did not contradict itself.' (Natural Theology, ch. 3)
Contemporary Relevance
Paley's argument raises the question of whether the appearance of design in nature requires explanation, and whether divine creation is a better explanation than natural selection plus cosmic coincidence. This question has not been resolved by Darwin's evolution - which explains biological complexity but not the fine-tuned cosmological constants that make biological complexity possible - and it continues to generate serious philosophical and scientific discussion. The broader question Paley raises - whether the universe gives evidence of intelligence, purpose, and care - is one of the most fundamental questions human beings face, and it is asked afresh by every generation.