The subscription controversy[clarification needed] was then agitating the university, and Paley pushed an anonymous defence of a pamphlet in which the Master of Peterhouse and Bishop of Carlisle Edmund Law had advocated the retrenchment and simplification of the Thirty-nine Articles; he did not, however, sign the petition (called the "Feathers Tavern" petition, from the place where it was agreed) for a relaxation of the terms of subscription to the Articles.

The book was published in 1785 under the title of The Principles of Moral and Political Philosophy, and was made a part of the examinations at the University of Cambridge the next year.

Paley strenuously supported the abolition of the slave trade,[5] and his attack on slavery in the book was instrumental in drawing greater public attention to the practice.

The main thrust of his argument was that God's design of the whole creation could be seen in the general happiness, or well-being, that was evident in the physical and social order of things.

Such a book fell within the broad tradition of natural theology works written during the Enlightenment; and this explains why Paley based much of his thought on John Ray (1691), William Derham (1711) and Bernard Nieuwentyt (1750).

"For my part", he says, "I take my stand in human anatomy"; elsewhere he insists upon "the necessity, in each particular case, of an intelligent designing mind for the contriving and determining of the forms which organized bodies bear".

Building on this mechanical analogy, Paley presents examples from planetary astronomy and argues that the regular movements of the solar system resemble the workings of a giant clock.

Thus, Paley's use of the watch (and other mechanical objects like it) continued a long and fruitful tradition of analogical reasoning that was well received by those who read Natural Theology when it was published in 1802.

The Edinburgh Review, for example, said "As a collection of striking facts and powerful arguments for the existence of a wise and beneficent Creator, this publication is certainly entitled to a very favourable reception.... Dr. Paley's chief excellence consists in the judicious disposition of his forces, and the skill and confidence with which he has extended his array to every point which atheism had affected to menace.

Earlier in the century David Hume had argued against notions of design with counter examples drawn from monstrosity, imperfect forms of testimony and probability (see watchmaker analogy).

In addition to Moral and Political Philosophy and the Evidences, Charles Darwin read Natural Theology during his student years, and later stated in his autobiography that he was initially convinced by the argument.

By the 1820s and 1830s, well-known liberals like Thomas Wakley and other radical editors of The Lancet were using Paley's ageing examples to attack the establishment's control over medical and scientific education in Durham, London, Oxford and Cambridge.

But whereas Paley's natural theology was disassembled or rebuilt by intellectuals like Wakley or the Bridgewater authors, the core of argument retained an ongoing popularity with the reading public and served as the basis of many catechisms and textbooks that were used in Britain and its colonies until World War II when, as argued by Matthew Daniel Eddy, the existential morass of World War I undermined the moral teleology that had underpinned natural theology since the Enlightenment.

Today, as in his own time (though for different reasons), Paley is a controversial figure, a lightning rod for both sides in the contemporary argument between creationism and evolutionary biology.